Cover art

"THE BLACK CROSS FLAG WAS HAULED DOWN, AND REHOISTED UNDER THE WHITE ENSIGN"

The Submarine Hunters

A Story of Naval Patrol
Work in the Great War

BY

PERCY F. WESTERMAN

Author of
"Rounding Up the Raider"
"The Dispatch-Riders"
"The Fight for Constantinople"
&c. &c.

Illustrated by E. S. Hodgson

BLACKIE AND SON LIMITED
LONDON GLASGOW AND BOMBAY
1918

Contents

Illustrations

[ "THE BLACK CROSS FLAG WAS HAULED DOWN AND
RE-HOISTED UNDER THE WHITE ENSIGN" . . . . . . . . . Frontispiece ]

[ THE INTERVIEW WITH THE GERMAN CAPTAIN (missing from book) ]

[ "'D'YE KEN YON?' ASKED THE BRITISH SKIPPER, AS HE
EYED THE PODGY GERMAN LEUTNANT WITH CONTEMPT" ]

[ "THE 'TREMENDOUS' WAS HEADING STRAIGHT FOR THE DOOMED SUBMARINE" ]

[ THE SINKING OF THE "ORONTABELLA" (missing from book) ]

[ "THE WORK OF DEMOLITION WAS ACCOMPLISHED" ]

THE SUBMARINE HUNTERS

CHAPTER I

The Mysterious Meeting on St. Mena's Island

"We've made a proper mess of things this time!" ejaculated Ross Trefusis—"or rather I have."

"It can't be helped," rejoined his chum, Vernon Haye. "We've done our level best to get her off. How long is it before the tide floats her?"

"A matter of seven or eight hours, worse luck. You see, it was only half ebb when we landed."

Ross bent down to remove a streak of bluish-grey mud from his ankle.

"I wish we'd taken the rowing-boat instead of this heavy old tub," he continued. "We'll be pretty peckish before we get back to the Hall, and dinner's at seven-thirty."

Vernon laughed.

"It wouldn't be the first time I've had to go without grub," he remarked. "If you don't mind, I don't."

"Then it's no use standing here," said Ross. "Let's get on our shoes and go for a stroll."

Vernon Haye was a broad-shouldered lad of fifteen, with clear-cut features and dark hair. His companion was of about the same age, but a good two inches taller. His complexion was florid, his hair of an auburn tint that narrowly escaped coming within the category of red or ginger. His features were full and rounded. In short, he was a typical Cornish youth.

Ross's father, Admiral Paul Trefusis, lived at Killigwent Hall, a large, rambling, sixteenth-century house, standing within a mile of the sea on the North Cornish coast.

Both lads went to the same public school, but owing to the fact that Vernon's father, Captain Haye, was on active service with the Grand Fleet, young Haye was spending the summer holidays with his chum at Killigwent Hall.

That afternoon the lads had taken a small sailing-boat and had made for St. Mena's Island, a small rocky piece of land lying about a mile off shore, and nearly five miles from Killigwent Cove. The island was roughly three-quarters of a mile in length, and four hundred yards wide in the broadest part. The north and west sides were precipitous, but on the side nearest to the mainland the ground sloped gradually, and was indented by several narrow tidal coves.

The glamour of romance lay thickly around that rocky pile. Centuries ago it was the abode of a hermit, who, amongst his various self-imposed tasks, had built a chapel on the summit, from the tower of which a wood fire was kindled nightly to warn mariners of the treacherous reefs in the vicinity of the island.

In course of time, St. Mena's Island became the haunt of wreckers and smugglers. The chapel, in spite of its massive construction, fell a victim to the ravages of wind and weather, but still served as a convenient shelter for the lawless Cornishmen who profited by the misfortunes of honest seamen. Immune from interference, by reason of the superstitious awe in which the island was held by the country-folk, the smugglers and wreckers thrived exceedingly until late in the eighteenth century, when stern measures were taken to suppress their misdeeds. From that time St. Mena's Island was deserted, except for the casual visits of tourists and summer visitors from the neighbouring towns of Padstow and Newquay, and countless numbers of sea-birds that take up their abode in crannies in the almost inaccessible cliffs.

Ross Trefusis was right in taking the blame of their misfortunes upon himself. He knew better, but, neglecting to take ordinary precautions, he had allowed the boat to be left high and dry by the falling tide. Upon returning to the cove the lads had found the heavy craft lying on its bilge in the stiff bluish clay, with a ridge of jagged rocks cutting her off from the sea.

"Perhaps," suggested Vernon, "some other boat will put off to the island, and we can get them to put us ashore."

"Hardly likely," was the reply. "Anyway, we'll keep a look-out. Which would you prefer to do—explore the Smugglers' Cave and Dead Man's Cave, or climb up to the ruins?"

"The ruins," decided young Haye eagerly. "I like fooling about old ruins, and I've already seen the caves. Besides, we can see if there are any boats about. It's almost like being shipwrecked on a desert island."

"Hard lines if we were," commented Ross. "Suppose we take an inventory of our possessions? Let the see: one pocket-knife, a silver watch that has refused duty, a notebook and pencil, and five shillings and three halfpence. What have you to add to the common stock?"

"A knife, a pocket compass, my watch—which does go; it's now five-and-twenty to four—and sixteen shillings and eightpence in paper money and hard coin."

"Not a morsel of grub between the pair of us, then," declared Ross. "Outlook beastly unpromising. Faced with starvation unless we make up our minds to knock over some gulls. They are horribly fishy to eat, I believe, and we've nothing to make a fire."

"It makes you pine for the flesh-pots of Kllligwent Hall, old man," exclaimed Vernon laughingly. "Never mind, let's make a move. I vote we get rid of these sweaters. It is frightfully hot."

Stripping off their woollen garments, and placing them for safety under a gorse bush, the two lads made their way up the steep ascent to the ruins, till, hot and well-nigh breathless in spite of being "in training", they reached the summit of the island.

"What a jolly view!" exclaimed Vernon, turning and taking in the panorama of rocky coast-line, an expanse of jagged, frowning, brownish cliffs topped by the brilliant green of the Cornish moorland.

"Not bad," agreed Ross complaisantly, for the view was no stranger to him. "See that cliff shaped like the head and shoulders of a bearded man? That's Hidden Money Cove that I was speaking to you about last night. We'll go there next week, all being well. You see, there's not a sail in sight, so our chances of getting back to dinner are very remote. What's more, unless I'm very much mistaken, there's a rain-storm coming. See that dark cloud working up against the wind?"

"Yes," assented Haye. "What of it? A little rain won't hurt."

"It's the after effect," said Ross. "It's quite possible it may blow hard before night, in which case we're done for. I've known it impossible to approach Killigwent Cove for a week at a time."

Vernon whistled.

"Sounds lively," he remarked.

"Of course that is in the winter," his chum hastened to remind him. "These summer gales don't last very long, but we'll be feeling precious hungry by the time we get home, I guess."

"Look here," said Vernon after a while. "I vote we get those sweaters. We don't want to be soaked."

"Very well," assented Ross. "But there's no great hurry."

Having retrieved the sweaters, the chums leisurely retraced their way to the ruins. For half an hour or more they wandered around the remains, descending into the dark crypt, and running considerable risk in climbing to the summit of the tower. Since the spiral stone steps had vanished long ago, the only means of getting to the top was by climbing the gnarled stem of the ivy which grew profusely on the face of the building. The tower was roofless, a low, partly demolished parapet encircling it on three sides, while a couple of weather-worn oak-beams supporting a few planks formed a kind of platform where the roof formerly existed.

"Think it's safe?" asked Vernon anxiously, as his chum, having got astride the parapet, was about to lower himself upon the decrepit woodwork.

"I've done it scores of times," said Ross confidently. "That's right, I'll guide your foot. Now let go."

"By Jove!" suddenly exclaimed Haye; "there's a fellow coming towards the ruin. How on earth did he get here?"

"Goodness only knows," said Trefusis inconsequently. "He may have landed in Main Beach Cove. Anyhow, he's at perfect liberty to do so. I suppose he's interested in ruins."

"Let's drop a bit of stone and give him a shock when he gets here," suggested Vernon. "We'll apologize afterwards. Ten to one he'll give us a passage back."

"I'm not so keen on dropping chunks of stone," objected Ross. "I vote we lie low for a bit at any rate, and see what he's up to."

"Why, do you think he's a spy?" asked his companion. Trefusis grunted scoffingly.

"Spy?" he repeated. "What object would a spy have on St. Mena's Island? This part of Cornwall is well outside the military area. There's nothing in the fortification line for miles. No, it's not that. But cave, here he comes."

The lads crouched behind the crumbling parapet, and by means of conveniently placed gaps in the masonry watched the stranger's approach.

There was nothing about the man's appearance to suggest that he was anything but an ordinary holiday-maker. He was slightly above average height, rather heavily built, and inclined to flabbiness. His complexion was undoubtedly florid, although his face and hands were tanned a deep brown.

He was dressed in a light-grey lounge suit, with a straw hat and brown shoes, while in his right hand he carried a thick Malacca cane.

The exertion of climbing up the hill on which the ruined chapel stood apparently told upon him, for he was considerably out of breath when he passed under the ivy-clad arch. Here he stopped to wipe his face with a handkerchief, and while doing so dropped his cane.

It fell upon the stones with a dull thud.

At the same time the stranger gave vent to an exclamation that certainly was not English.

The lads exchanged glances. Here was the beginning of a mystery. The heaviest Malacca cane would not have made that dull metallic sound in falling, while it was evident by the careful examination the stranger made of the retrieved article that he was more than considerate for its appearance.

The man made no attempt to explore the ruins. The weather-worn fane had no attractions for him. It was apparently only a rendezvous, as far as he was concerned, for at frequent intervals he would walk stealthily through the archway, and look attentively down the hill leading to the coves on the side facing the mainland.

It had now begun to rain—big drops that were the precursors of a heavy shower. The lads, in their exposed position on the tower, paid scant heed. Their interest and attention were centred upon the anxiously awaiting stranger fifty feet beneath them.

Presently Ross happened to glance towards the stretch of water that separated St. Mena's Island from the mainland. A boat was approaching. Already it was more than half-way across. It was a rowing-boat, containing only one person. What object would anyone have in rowing across on a wet afternoon like this? wondered the lad.

Just then the stranger began rubbing his hands with ill-concealed satisfaction. Although he had been frequently on the look-out, he had evidently only just caught sight of the approaching boat.

The lads watched the little craft till it was hidden by the intervening high ground, but already Ross felt certain that it was making for Main Beach Cove.

There were three landing-places on St. Mena's Island—Half Tide Cove, where the lads had left their stranded boat; Main Beach Cove, a little to the north-east; and Deadman's Cove, farther away. Of these, only Main Beach was available between one hour on either side of low water. The fact that the boat was making for it, and had already successfully skirted the submerged reef lying off it, proved that its occupant had local knowledge.

Some considerable time elapsed between the temporary disappearance of the boat and the appearance of the new-comer; but at length he came into view, walking rapidly up the steep incline without showing anything of the physical strain that the first stranger had betrayed.

Suddenly Ross Trefusis recognized the man. He almost felt inclined to laugh at his suspicions. It was Dr. Ramblethorne, the medical practitioner at St. Bedal—a town of considerable importance about seven miles from Killigwent Hall. The doctor was a frequent guest of Admiral Trefusis, and was generally considered a good, all-round sportsman. He was about thirty years of age, over six feet in height, of sinewy frame and of great muscular power. He was the wildest motorist in that part of Cornwall, as the endorsements on his driver's licence testified. A keen golfer, good shot, and fisherman, he was also a botanist; and that, perhaps, thought Ross, might account for his presence on St. Mena's Island, although it was difficult to reconcile the fact that Ramblethorne had an appointment with a stranger at this desolate spot. If a joint botanic expedition had been fixed up, why had not the two men met on the mainland?

The unknown made no attempt to advance to meet the doctor. Instead, he remained within the ruins until Ramblethorne entered.

Their greeting was a surprise even to the lads, for the doctor, holding out his hand, exclaimed in German:

"Well met, von Ruhle! Let us hope that your arrangements will prove satisfactory."

CHAPTER II

The Tables Turned

Both Ross Trefusis and Vernon Haye understood and could speak German. Ross was especially good in his knowledge of the language of the modern Hun, for in his early youth he had been inflicted with a German governess. Since German is one of the subjects for Sandhurst—for which both lads were preparing—their knowledge had been considerably improved under the cast-iron rule of a native professor.

"Eminently satisfactory," replied von Ruhle. "We will go into details later. You had no difficulty in coming here, I hope?"

"None whatever."

"No suspicions?" asked von Ruhle anxiously.

Ramblethorne smiled.

"My dear von Ruhle," he replied. "A medical practitioner is above suspicion. He is free to go anywhere at any hour of the day or night without question. No man would suspect——"

"You are clever, von Hauptwald——"

"Ssh!" interrupted the doctor. "Call me Ramblethorne, if you please. Of course there is no danger here, but at other times and in other places you might incautiously give the show away. You had a good passage?"

"Excellent," replied von Ruhle. "I am getting well-known to the strafed English custom-house officers at Queenboro' and Harwich. They recognize me by my stick, I believe, but they little know that it is a new one every time. What do you think of this? I have brought it as a specimen for you to see. Just fancy! every time I cross to Holland twenty kilogrammes of good copper are on their way to the Fatherland. By this time Herr Stabb of Essen is well acquainted with my Malacca canes."

"A good weight to carry about," remarked Ramblethorne, wielding the disguised bar of copper. "I wonder you troubled."

"Mein Gott! I could not leave it," declared von Ruhle. "Someone might take a fancy to it, and then the secret would be out. But tell me: have you succeeded in getting that commission you spoke of?"

"I am still living in hopes," replied Ramblethorne. "Of course I could have obtained a post of temporary surgeon in the British Navy, but it wasn't good enough. It's no fun running the risk of being torpedoed by our own Submarines. The English Army offers a wider scope. Believe me, I am worth more than a division to the Emperor. I'll get a commission, never you fear, for I have heaps of influence. Then, of course, I will do my utmost to fight against a terrible epidemic that will mysteriously break out amongst the troops."

Ramblethorne, otherwise von Hauptwald, threw back his shoulders and laughed uproariously.

"Careful!" hissed his companion. "You will be heard over the whole island."

"What matters? There is not another soul in sight besides ourselves. How much petrol have you?"

"Fifty two-gallon tins. I expect some more by boat to-morrow. It's safely stored in a cave on the side of the creek. It is a nuisance it is raining. I do not fancy a night's work in weather like this. Himmel, what's that?"

Accidentally Vernon's foot had dislodged a small piece of stone.

"Nerves, my dear von Ruhle," said Ramblethorne, with his usual good-natured smile. "A bit of masonry has fallen from the tower. See, the floor is covered with similar pieces."

"If anyone should be up there——" suggested von Ruhle, pointing to the top of the tower.

The lads could feel their hearts thumping against their ribs. Through a small crack in the planking they could see the eyes of the two Germans directed upwards.

"Impossible; there are no steps," declared Ramblethorne. "Besides, what object would anyone have in ascending a tower on a day like this? I fully appreciate the danger of being overheard, of course. We've said enough to find ourselves faced by a firing-party in the Tower of London, my friend."

"Don't!" expostulated von Ruhle, closing his eyes as if to shut out the unpleasant mental vision. Then: "You have the signalling apparatus, I hope?"

"Trust me for that, von Ruhle," replied his companion, tapping his breast-pocket. "All we have to do is to wait until yonder lighthouse exposes its light. Really the ways of these English pass understanding. They rigorously forbid the showing of lights in private houses on shore, imagining that our agents would be so foolish as to start blinking with a lamp; yet they allow these lighthouses to work as usual, and obligingly enable us to communicate to our hearts' content."

Von Hauptwald was not far wrong in his remarks, for the instrument he had enabled him to flash a message to a confederate without having to be in possession of a lamp. The flash was obtained from any distant and visible light by means of a complicated system of mirrors. The reflected rays could then be projected in any desired direction so as to be quite invisible except on a certain bearing. It was one of the carefully-thought-out plans adopted by the German Government to permit its spies to communicate with their submarines without running any great risk of detection.

"It's two hours to sunset," remarked the doctor; "three before we commence operations. I would suggest that we adjourn to the cave and partake of refreshment. You see, I have not omitted to make suitable provision."

"Very good!" agreed von Ruhle; "but I only wish I had a waterproof. The rain is most annoying."

Arm-in-arm the two men left the building, and presently disappeared from view behind a slight rise in the ground.

"I say!" exclaimed Ross; "we've tumbled on something this time. Fancy Ramblethorne a rotten German spy. I always thought he was a rattling good chap."

"Evidently he isn't," rejoined Vernon. "But the point is: what do you propose to do? It's beastly wet here."

"It is, now I come to think of it," agreed his chum. "The fact is, that until you mentioned it I was hardly aware that it was raining. We'll discuss this knotty point."

"I vote we make tracks for the boat," suggested Haye. "The tide must be rising by this time. We can then slip off and raise the alarm."

Ross shook his head.

"No go," he decided. "We might get nabbed ourselves. Besides, who would be able to lay these chaps by the heels? There's only that motor-boat chap at Penydwick Cove, and he's precious little use. There are no soldiers nearer than at St. Bedal. I propose we hang on here. There's a snug, sheltered hole in these ruins, just big enough for us to lie hidden. Then we stand a good chance of hearing more of the conversation between those beggars."

"Three hours more, remember."

"Yes, I know. In the meanwhile we might slip down to Main Beach Cove. There's plenty of cover amongst the rocks."

"What for?" asked Vernon.

"To see what these fellows are up to. I'm rather anxious to renew my slight acquaintance with friend Copperstick. By Jove, what a cute move to get contraband metal into Germany!"

"Not much at a time. It shows how hard up the Germans must be for copper when it pays a fellow to carry over about half a hundredweight at a time."

"Well, let's get a move on," said Ross. "Be careful how you descend. The ivy will be fairly slippery with the wet."

Cautiously the two lads descended, reaching the ground without mishap.

"Our sweaters!" exclaimed Vernon.

"Dash it all! Yes," agreed his companion. "I had forgotten all about them."

The sweaters, carefully rolled up, had been placed for security in one corner of the chapel. Unless anyone actually came close to the spot, they were hidden from sight.

"Neither of those fellows stood about here, I think," remarked Ross as the chums retrieved and donned the additional clothing. "It's jolly lucky, or they would have smelt a rat."

Trefusis and his companion went out into the rain, walking rapidly towards a slight mound capped by a few irregularly shaped stones. It was behind this rise of ground that the two spies had gone. Up to this point, Ross argued, there was little need for caution; beyond, it would be necessary to keep well under cover until they reached Main Beach.

"'Ware the skyline," cautioned Ross as the chums approached the hillock.

"Ay; 'ware the skyline," said a deep voice mockingly, "It's bad strategy."

Turning, the lads made the disconcerting discovery that Ramblethorne and von Ruhle were within five yards of their would-be trackers.

Ross realized that he and his chum had been badly outmanoeuvred. Evidently the Germans suspected that they had been overheard, and ostentatiously leaving the ruins for Main Beach Cove, they had made a detour from the hillock, and had waited until Ross and Vernon had emerged from the chapel. Then, taking advantage of the wet grass that effectually deadened the sound of their footsteps, they had turned the tables on their shadowers.

So completely taken aback were the two lads that they stood stock-still as if rooted to the earth.

"Not a nice evening to be out, Trefusis," continued the doctor. "What brings you on St. Mena's Island at this late hour of the day?"

"Our boat was left high and dry by the tide, so we had to wait and take shelter," replied Ross.

"And so you chose a place where there was no shelter," remarked Ramblethorne. "Idiotic thing to do—very idiotic. Now tell me: what were you doing on the top of the tower?"

Ross did not hesitate in his reply. Perhaps it would have been better had he done so, for he had never betrayed his knowledge of German to the doctor on any of their previous meetings, and it would have been judicious to keep up the deception.

"What were we doing? Listening to your precious schemes," he retorted boldly. "Now we know all about you, and it will be our duty to report you as spies to the authorities. We are expecting a search-party from Killigwent Hall at any moment, you see."

"So that's the line of defence you propose to adopt, eh?" sneered Ramblethorne. "Well, look out!"

With a sudden spring the athletic man flung himself upon Ross, while von Ruhle with equal promptitude made a rush to secure Vernon.

Strong and active though he was, Ross was no match for his huge and powerful antagonist. Knowing that flight was impossible, the lad feinted, and aimed a blow with his left straight for the doctor's chin. This Ramblethorne parried easily, and grasping the lad's wrist, held it as in a vice, and in such a manner that rendered fruitless any attempt on Trefusis' part to make use of his right arm.

Having thus secured his opponent, Ramblethorne watched the result of the encounter between his fellow-spy and young Haye.

Von Ruhle had opened the attack by brandishing his heavy stick, and calling upon Vernon to surrender.

Haye returned the compliment by closing, and dealing the German such a terrific blow upon the chest that von Ruhle recoiled quite a couple of yards. The lad's onslaught had only missed the German's solar plexus by a few inches; had it not, the chances were that von Ruhle would have lost all interest in life for the next quarter of an hour.

But instead of following up his initial success Vernon, seeing Ross helpless in the doctor's grip, rushed to his chum's aid. For a few seconds he feinted, striving to find an opening, while Ramblethorne, dragging his captive with him, pivoted in order to keep his front towards his new antagonist.

Those few seconds were Vernon's undoing.

Quickly recovering himself, von Ruhle sprang forward with the agility of a panther. The imitation Malacca cane descended with a dull thud upon the lad's head, and like a felled ox Vernon fell inertly upon the sodden grass.

"Hold him—so," exclaimed Ramblethorne, handing Ross over to the custody of von Ruhle. Then drawing a small hypodermic syringe from a case, the former inserted the needle into the lad's forearm.

Five seconds later Ross Trefusis lay unconscious beside his companion in misfortune.

CHAPTER III

Kidnapped

"I thought you had killed him, von Ruhle," said the doctor, bending over Vernon and making a cursory examination of the unconscious lad.

"I thought I had," was the unconcerned reply. "Dead men tell no tales."

"There I beg to differ," protested Ramblethorne. "Corpses have a nasty way of turning up at inopportune moments. These youngsters are worth more to us alive than dead."

"How so?"

"One is a son of Admiral Trefusis; his companion is, I believe, also a son of a distinguished English naval officer."

"Well, and what of it?" asked von Ruhle.

"Hostages," replied the doctor briefly. "Later I will explain. Meanwhile we'll carry them to the cave. It's farther than back to the ruins; but perhaps, as young Trefusis said, there may be a search-party, and the ruins would be one of the first objects of investigation."

Although, with the exception of periodical visits abroad, Dr. Ramblethorne had lived in England all his life and was a fully qualified medical man, he was a highly trusted and talented agent of the German Secret Service. Months before the outbreak of war, he had been ordered to report upon the defences of Devonport, and in order to do this he had bought a practice on the outskirts of Plymouth. Upon the commencement of hostilities, he was detailed to keep under observation the military preparations of the Duchy of Cornwall, and also to take necessary steps for communicating with German submarines that, under von Tirpitz's prearranged scheme, were to operate in the Bristol Channel. Von Ruhle was one of the few subordinates he actually knew. There were others with whom he communicated only through an intermediary, and who knew him only by a number.

Von Ruhle was almost as mentally clever as his superior. Ostentatiously he was an Englishman. Sometimes he posed as a mining engineer; at others as a commercial traveller; as an accredited representative of the British Red Cross Society he was in the habit of making frequent journeys to Holland, presumably in connection with work at Groningen Internment Camp. At the present time, his activities were centred upon the formation of a secret petrol depot for the supply of fuel to unterseebooten operating in the Bristol Channel and off the south coast of Ireland.

A couple of slight incidents had served to put the cautious Ramblethorne on his guard during his interview with von Ruhle in the ruined chapel.

Although he verbally deprecated his subordinate's alarm when the lads accidentally dislodged a stone from the tower, it was merely to disarm possible eavesdroppers of any suspicion that their presence was suspected.

The ability to control his feelings was one of the super-spy's chief assets. Suspicion once aroused, he proceeded without the faintest sign to investigate his surroundings. His keen eye soon lighted upon the lads' sweaters. Then it was that an adjournment was suggested to Main Beach Cove.

This was simply and solely a "blind", for on gaining the cover of the boulder-strewn hillock the doctor communicated his suspicions to his companion. The pair then crouched behind the rocks, whence they were able to command a view of the tower.

It was not long before their enterprise met with success. They saw Trefusis and his chum cautiously descend by means of the ivy; then, directly the lads set out upon their ill-starred tracking expedition, the Germans, as before related, succeeded in outflanking them and effecting their capture.

"Time!" announced Ramblethorne, consulting his watch.

"Are these safe?" asked von Ruhle, stirring Vernon's unconscious form with his foot.

"Quite; though, perhaps, to make sure I will give this youngster a slight injection. Pity you hadn't held him with the double arm-lock instead of cracking him over the head. Herr Kapitan Schwalbe won't want to be troubled with a passenger with a swollen head."

Leaving their senseless victims in the cave, the two Germans again ascended the hill to St. Mena's Chapel. As they breasted the summit, they could see the fixed white light of Black Bull Head showing momentarily brighter and brighter against the rapidly failing daylight.

Setting a prismatic compass in position upon the sill of one of the glazeless windows, Ramblethorne took a careful bearing in a seaward direction. This done, he pointed the projector of the signalling apparatus in precisely the same direction, and threw a waterproofed cloth over the instrument.

"Too early yet, von Ruhle," he remarked. "Nevertheless it is advisable to fix our bearings while twilight lasts. A light might spell disaster."

"A deucedly unpleasant night for such a task," grumbled von Ruhle.

"On the contrary, it is just the very thing," replied the doctor. "It is not thick enough to be dangerous, but the rain is just sufficient to assist in the screening of U75. Do not think of your personal comfort, my dear von Ruhle, when urgent work for the Fatherland has to be undertaken."

For another half-hour the two men paced the grass-grown stones. Their choice of St. Mena's Island as a secret signalling station was an excellent one. It was isolated, and, being slightly greater in elevation than the cliffs of the mainland in the immediate vicinity, would effectually screen any ray of light sent landwards from the expected German submarine. Thus all danger of the narrow gleam of reflected light being detected by the none too smart members of the coast patrol was entirely obviated.

"Time!" exclaimed the doctor, consulting the luminous face of his watch.

Dexterously, and without disturbing the position of the instrument, von Ruhle whipped off the covering. Although there were no visible signs that anything was taking place, both men knew that a beam of light, reflected from the distant lighthouse on Black Bull Head, was being directed seawards.

In silence the two men peered through the driving rain, von Ruhle making use of a pair of powerful night-glasses.

Suddenly, after an interval of almost five minutes, a faint pin-prick of light flickered from the surface of the sea.

Instantly Ramblethorne stepped a dozen paces to the right.

"I can see nothing from here," he announced in a low voice. "Can you?"

"Yes," replied his companion.

"Good: that's friend Schwalbe."

The doctor was right. From the deck of the unterseeboot a signalling apparatus similar to that employed by the spies was in use. By an ingenious automatic arrangement it projected a beam of light, derived from the same sources as that on St. Mena's Island, rigidly in a fixed direction, regardless of the "lift" of the submarine under the action of the waves.

For several minutes a rapid exchange of signals was maintained; then the two spies, folding up their apparatus, walked rapidly towards Main Beach Cove.

They had not long to wait before the faint sound of oars was borne to their ears.

"Himmel! They have arrived already," exclaimed von Ruhle.

"So it appears," replied Ramblethorne dryly. "I pride myself that I have exceptionally good eyesight, but I fail to see her. The neutral colour of the submarine is indeed excellent for night work."

They descended the sandy and shingly beach until further progress was barred by the lapping wavelets of the rising tide.

Through the mirk loomed up the outlines of a canvas collapsible boat crowded with men. At two lengths from the shore the rowers laid on their oars. One of the men gave vent to a low whistle resembling the call of a curlew.

"All clear," replied Ramblethorne.

The boat's keel rasped on the shingle. A cloaked figure in the stern-sheets made his way for'ard and leapt ashore.

"Herr von Hauptwald?" he asked.

"The same," replied the doctor. "And Kapitan Schwalbe?"

"The captain is still on board," replied the officer. "It is hard to resist the opportunity of getting ashore after being cooped up there for more than a fortnight. But the petrol?"

"We have not so much as we hoped to obtain," replied von Ruhle.

The Leutnant muttered an oath.

"And how is business?" asked Ramblethorne, with a view of distracting the officer's thoughts from the shortage of fuel.

The Leutnant muttered another oath.

"Bad!" he replied savagely. "Only one wretched little tramp steamer, which we fell in with about twenty miles from the Stacks. She gave us a run for our money, but we had her at last. Even then she tried to ram us. One has to be most cautious also. These accursed English have been far too active with their new-fangled contrivances. We called up U71 early this morning. She replied. Again at noon we called her, but there was no reply. U70 we have lost all touch with since Monday, yet she was under orders to assist in the blockade of the Bristol Channel until we, as senior unterseeboot, gave instructions to return to Wilhelmshaven."

"Lost, I suppose," remarked Ramblethorne.

The Leutnant had walked to a distance of nearly ten yards from his men, who were drawn up in military order awaiting their officer's commands.

He lowered his voice.

"Although I am sorry to say it," he declared, "I am afraid she has gone too. Our losses are not only serious—they are appalling. Submarine work is now a continual nightmare. We do our duty, but before long, if we are sufficiently fortunate to escape the toils that these English cast about us, we shall all be physical wrecks."

The man's agitation increased as he spoke. Obviously he was labouring under a severe strain.

"And this petrol?" he asked anxiously. "What quantity?"

Ramblethorne told him.

"Not enough," declared the Leutnant. "Himmel, it is not enough to get us round Cape Wrath. On board we have only sufficient for six hours' surface running, while our batteries are not far short of running down. You had better see the captain and explain."

Leaving von Ruhle to direct the seamen to the secret petrol store in the cave, Ramblethorne accompanied the Leutnant to the submarine.

The U75 was one of the latest type of Germany's submarines. Over three hundred feet in length, there was little about her in common with the accepted idea of under-water craft. Her deck ran in one continuous sweep for almost her entire length, and rose nearly six feet above the surface. The visible part of her sides was perpendicular, the bulging sections being entirely beneath the surface. Her conning-tower was surrounded by a platform as long as the navigation-bridge of a modern destroyer. The two periscopes were "housed", but two slender "wireless" masts gave the boat the appearance of a swift torpedo craft.

Acknowledging a salute from a burly quartermaster, Ramblethorne gained the deck, and was escorted aft by the Leutnant. Pacing the tapering platform was a broad-shouldered, fair-haired man of about thirty, although a carefully trimmed blonde beard made him look much older.

He lacked the natural elastic stride of the British naval officer. His movements resembled those of a thoroughly drilled soldier, yet ever and anon he would glance furtively in the direction of the open sea as if in constant dread of sudden and unknown peril.

"Greetings, Herr von Hauptwald!" he exclaimed, when the Leutnant had formally introduced his visitor. "You are well known to me by repute, but I doubt whether we have met before."

"I fancy so," rejoined the doctor. "Do you not remember that little affair in the Strauer Platz? Ah, I thought you would! But to come to the point. We have been unable to obtain the requisite quantity of petrol."

"Somehow I thought it," replied Kapitan Schwalbe. "How much have you?"

Ramblethorne told him.

"Enough, with what we have left on board, for only eight hundred miles run. It will not take us home, and we are under orders not to leave these waters before Friday next. We have been let down badly."

"I know that it is useless to express regrets," said Ramblethorne boldly. "I can only hope that other means of supplying the requisite fuel will be forthcoming. But here is another matter. We have had to secure two English lads, both sons of distinguished naval officers. Unfortunately they overheard a conversation between von Ruhle and myself. In the interests of the Secret Service it is absolutely necessary that they are kept out of the way for at least a couple of months. I am averse to doing them personal injury."

"Then what do you wish?" asked Kapitan Schwalbe.

"Take them on board with you. If possible, land them at a German port. If this be possible, you will realize that we have a strong tool to work with."

"I fail to understand," said the Kapitan of U75.

"They could be made good use of as hostages," resumed Ramblethorne. "If these English persist in talking about reprisals, we can hint that—well, it is unnecessary to go into details."

"I see," remarked Kapitan Schwalbe. "But if it is impossible to land them?"

"Then you must put them on board the first outward-bound tramp steamer you fall in with—provided she is bound for South American ports, or anywhere that will mean a long voyage."

"Very well," assented the submarine officer. "I quite understand your anxiety to get them out of the way."

"Temporarily, mind," added Ramblethorne.

"Precisely. Herr Rix," he exclaimed, addressing the Leutnant. "Take four men and go ashore. Von Ruhle will tell you where these English boys are; have them brought on board."

"One moment," interrupted Ramblethorne. "They came to the island in a boat. There is nothing unusual in that, I admit, but the fact remains that the boat is still lying in the cove next to this. You might order the men to set the boat adrift."

"Water-logged, and with sails set and the main-sheet made fast. Another deplorable accident. Ach! It shall be so."

Half an hour later Ross Trefusis and Vernon Haye, still unconscious under the action of the anaesthetic injection, were brought on board U75 and passed below. Their boat, lying on its beam-ends, was drifting slowly in the direction of Black Bull Head. Ramblethorne and von Ruhle, their work for the present done, were already on the way to the mainland.

Meanwhile, alarmed at the non-appearance of the young heir to Killigwent Hall and his guest, a party had set off to search St. Mena's Island.

Just as the boat's keel grounded on the beach of Half Tide Cove, the German submarine slipped quietly through the blurr of misty rain, and under cover of darkness headed towards the mouth of Bristol Channel.

CHAPTER IV

The Awakening

"Dash it all! What am I doing here?" muttered Ross Trevor drowsily, as he opened his eyes.

For the moment he quite imagined that he was in his dormitory at school, and that by an oversight the rest of his chums had left him in bed. The suggestion was strengthened by the sound of gurgling water, as if the bathroom tap were running. Then he became aware that everything was pitching up and down. Once before he had experienced a similar sensation—when he had had a violent headache following a slight touch of sunstroke.

It puzzled him, too, that he was almost in darkness. Somewhere without, and partly screened by some projection, an electric light was burning. The reflected rays were just sufficient to enable him to take stock of his surroundings.

No, he was not back in the school dormitory. True, he had a headache, but that would not account for the actual motion. He fumbled, his fingers came in contact with a curved board that served to prevent the occupant of the bed—or, rather, bunk—from falling on the floor.

Almost mechanically he rolled out, and stood supporting himself by grasping the ledge of the bunk. The swaying, due partly to dizziness and partly to an unaccountable see-saw motion, would have thrown him to the floor but for the assistance afforded by the side of the bunk.

Gradually he became aware that there was a similar sleeping-place immediately beneath the one he had been occupying. Someone was lying there, breathing heavily. There was sufficient light for Ross to recognize him. It was his chum Vernon.

Just then a bell clanged noisily. The sound of running water was outvoiced by the loud din of machinery in motion. A wave of hot air that reminded the lad of the atmosphere of a Tube station wafted past him. The whole fabric trembled under the powerful pulsations of the mechanism.

With his legs trembling through sheer physical weakness, Ross hung on grimly. He wanted to shout, but no sound came from his parched tongue. He was bewildered. It seemed as if he were in the throes of a terrible nightmare, and that he would awake on finding himself falling into a bottomless abyss.

The reflected light was obscured as a broad-shouldered man made his way along the narrow corridor in which the bunks were placed. As he did so he caught sight of the lad. Without a word he seized Ross in his arms, not roughly, but nevertheless unceremoniously, and lifted him back into the bunk. There was something so peremptory in the action that Ross lay still and closed his eyes. All his will power seemed to have deserted him.

"Make a dash for it, old man!" exclaimed a muffled voice that Trefusis hardly recognized as his chum's. "Make a dash for it. Don't let them collar us."

It was Vernon rambling in his sleep. The words were sufficient to give Ross a key to the hitherto baffling problem.

Like a flash he recalled the episode of their adventure on St. Mena's Island. He remembered himself being held in the grasp of the powerful Ramblethorne until unconsciousness overcame him. He was still a prisoner, but with the qualifying knowledge that he was not alone. Vernon Haye was sharing his captivity, wherever it might be.

"We're afloat then," he muttered. "What has happened?"

Moistening his lips, Ross leant over the side of the bunk and called his chum by name. His voice sounded strangely unfamiliar. He could only just hear himself above the clamorous noise of the engines.

It was not long before another man appeared at the end of the corridor. As he did so he switched on a lamp almost above the lad's head. For a few seconds Ross was temporarily blinded by the sudden transition from artificial twilight to the intense brilliancy of electric light.

"So! You are now awake, hein?" asked a guttural voice. "How you vos feel?"

"Rotten!" replied Ross emphatically. His reply was brief and to the point. It summed up his sensations during the last ten minutes.

The man laughed.

"So you look. You better soon will be. You know where you now vos?"

"On board a ship," answered the lad. He was still hoping against hope that his questioner was anything but a German. There was a small chance that he had by some means been picked up at sea by a Dutch or a Swedish vessel.

The man's announcement "put the lid on" that possibility.

"Sheep—goot!" he chuckled. "German unterseeboot—vot you vos call submarine. No danger to you boys if you yourselves behave. Much to see—ach! plenty much."

The lad's eyes had now become more accustomed to the light. He could see that his visitor was a broad-shouldered, muscular man of average height, florid-featured, and with light-yellow hair and a fair moustache. He was dressed in a uniform that was apparently a bad copy of that worn by executive officers of the British Navy. On the breast of his coat he wore an Iron Cross.

"Me Hermann Rix, Ober-leutnant of unterseeboot," he announced. "Der Kapitan send me to see how you get better. Goot! I tell seaman to bring food quick. In one hour you go on deck. Den you feel all well."

The German Leutnant bent and peered into the lower cot.

"Fat head," he remarked seriously. "Bad knock, but he get well soon."

With that the officer went away, leaving the light switched on.

Scrambling out of his bunk, Ross approached his chum. Vernon was now sleeping quietly. His face, however, was flushed, while it was quite evident that he had received a fairly heavy blow across the skull, for the top of his head was swollen to a considerable extent.

Before Ross had finished his examination a sailor entered, bearing a tray on which were three slices of rye bread, some tinned beef, and a bottle of Rhenish wine.

"Sprechen Sie deutsch?" he asked.

For an instant Trefusis hesitated before replying. To profess ignorance of the German language would be an immense advantage while on board the submarine, provided he could control his facial expressions and listen without betraying himself. Then, on the other hand, he reflected that Ramblethorne, the spy, might have been instrumental in getting him into this predicament. More than likely the Captain of the submarine had been informed of the fact that his unconscious passengers were well acquainted with the tongue-twisting language of the Fatherland.

"Here is food for you," said the man, placing the tray on the floor. "You had better take hold of the bottle before it upsets. We are rolling a bit. When your friend open his eyes, call me. I am in yonder compartment. It would be well for you to dress. I will bring your clothes to you very soon."

Ross made a sorry meal. The food was not at all appetizing. His throat was in no condition to enable him to swallow easily. A feeling of nausea, due either to the motion, the hot, confined air, or the after effects of the stupefying injection—perhaps a little of all three—was still present.

He was actually on board a German submarine—one of Tirpitz's twentieth-century pirates. He racked his brains to find a reason. With its limited accommodation an unterseeboot seemed the last type of craft that would receive a pair of prisoners—and non-combatants—within its steel-clad hull. It must have been at Ramblethorne's instigation; yet why had not the spy knocked the pair of luckless eavesdroppers over the head and tumbled them into the sea? It seemed by far the easiest solution; yet, in spite of that, Ross and Vernon were being carried to an unknown destination in one of the "mystery-craft" of the Imperial German Navy.

The reappearance of the seaman bearing Ross's clothes cut short the latter's unsolved meditations. Without a word the man laid the neatly folded garments on the bunk—a pair of flannel trousers, cricket shirt, underclothes, and the sweater that had been the cause of the lads' undoing; but in place of his shoes a pair of half-boots, reeking with tallow, had been provided.

Ross proceeded to dress. As he did so a voice that he hardly recognized asked:

"Hulloa, Trefusis, where are we?"

It was Haye. His companion was now awake, but hardly conscious of his surroundings.

"Better?" asked Ross laconically. He could not at that moment bring himself to answer the question.

"Didn't know that I was ill," remonstrated Vernon. Then, after a vain attempt to raise his head—perhaps fortunately, since the bottom of Ross's cot was within a few inches of his face—he added:

"Dash it all! I remember. That beastly German gave me a crack over the head with his copper walking-stick. Where are we?"

"In a rotten hole, old man. We're in a German submarine, bound goodness knows where."

"Where are my clothes?" asked Haye, this time successfully getting out of his bunk. "Since you have yours, there seems to be no reason why I shouldn't have mine. Hang it! What's the matter with me? Everything's spinning round like a top."

Mindful of the seaman's words, and with a docility that would have surprised him in different circumstances, Ross staggered along the corridor. The passage was about thirty feet in length. On one side the metal wall was flat, on the other it had a pronounced curve. Against it were six bunks arranged in pairs. Four were used as stowing-places for baggage, the remaining ones had been given up to the two prisoners. The roof was almost hidden by numerous pipes, most of them running fore and aft, while a few branched off through the walls. The flat bulkhead evidently formed one of the walls of the engine-room, for, as the lad placed his hand against it to steady himself, he could feel a distinct tremor, quite different from the vibration under his feet. The floor was of steel, with a raised chequer pattern in order to give a better grip to one's feet. At frequent intervals there were circular places, similar to those covering the coal-shoots in the pavement of residential thoroughfares. Walls, ceiling, and floor were covered with beads of moisture, but whether from condensation or leakage Ross could not decide.

At the end of the corridor or alley-way was a steel water-tight door, running in gun-metal grooves packed with india-rubber. The door was closed.

Seizing the lever that served as a handle, Trefusis tried to turn it, but without success. Failing that, he kicked the steelwork with his heavy half-boots, yet no response came to his appeal.

"The fellow told me to call," he muttered airily. "What did he want to play the fool for?"

Retracing his steps, Ross went to the other end of the alley-way. There was barely room to pass his companion as he did so. The place from which he had previously seen the reflected light was now shut off by a door similarly constructed to the one that he had vainly attempted to open. He was locked in a steel tomb that was itself a metal box within a metal box—a water-tight compartment of the submarine.

"They might just as well have switched off the light while they were about it," he exclaimed bitterly; then at the next instant he wildly regretted his words. The idea of being imprisoned in that cheerless compartment without a light of any description appalled him.

Almost frantically he returned to the door that had previously baffled him. As he did so he became aware that the submarine was tilting longitudinally. Since he was unaware of the direction of the craft, and which was the bow or stern, he was unable to judge whether the unterseeboot was diving, or ascending to the surface.

The incline became so great that he had to grasp the door-lever for support. Turning his head, he saw that Vernon was hanging on grimly to the partition between the tiers of bunks.

Then, as the vessel regained an even keel, silently and smoothly the door slid back in its grooves, revealing a small space barely six feet in length and five in breadth, and separated from the rest of the vessel by a closed water-tight panel. Part of the compartment was occupied by a bend, at which the seaman to whom he had previously spoken was busily engaged in mending a rent in an oilskin coat.

"My friend is now awake," announced Ross.

The man laid aside his work.

"Good!" he replied. "He is just in time. I will bring him his food and his clothes. After that you will both go on deck for fresh air before you are interviewed by Herr Kapitan Schwalbe. See that door? Beyond that you must not pass without permission. It is forbidden. If you do so, you will not have another opportunity in a hurry."

"What are they going to do with us?" asked Ross.

The sailor shook his head.

"It is forbidden to ask questions," he said sternly. "Whatever is necessary that you should know will be told you."

He turned his back upon his questioner, signifying in a plain manner that it was useless for Trefusis to say more. Taking the hint the lad returned to his chum, wondering deeply at the fate that had thrown them into the hands of the enemy.

CHAPTER V

Aboard U75

Like Ross, Vernon Haye made a poor meal. He had barely finished when a petty officer appeared and curtly ordered the lads to follow him. Since he did so in German it was fairly certain that Trefusis' admission had been communicated to both officers and crew.

Staggering, they passed along the alley-way into a broad subdivision that extended completely athwartships. It was one of the two broadside torpedo-rooms, and contained two tubes of slightly greater diameter than the British 21-inch. In "launching-trays" by the side of the tubes were eight torpedoes with their deadly war-heads attached. Both transverse bulkheads were almost hidden by indicators, voice-tubes, and pipes for transmitting the compressed air from the air-flasks to the torpedo-tubes.

Passing through another water-tight door the prisoners found themselves in yet another compartment. On one side was an "air-lock", with its complement of life-saving helmets; on the other was an oval-shaped door forming means of communication with the small room built against the curved sides of the submarine. Ross guessed, and rightly as it afterwards transpired, that the door led into a space that could be flooded at will, and which in turn enabled a diver to operate from the U-boat while submerged.

Confronting the lads was an almost perpendicular steel ladder communicating with the conning-tower. Their guide was about to ascend when a stern voice exclaimed in German:

"Not that, you idiotic clodhopper! Have you lost your reason? The forward hatchway, don't you know?"

"Pardon, Herr Leutnant," said the petty officer, abjectly apologetic, and, backing down the ladder, he passed through another door entering into an alley-way between the officers' cabins. Here was the bowl of a supplementary periscope, so that a vision of what was taking place could be obtained without going into the conning-tower.

The alley-way terminated at another broadside torpedo-room, the pairs of tubes pointing in the opposite direction to those the lads had just seen.

Beyond were the living-quarters of the crew, kept spotlessly clean and tidy, yet Spartan-like in their simplicity. Two of the men were sound asleep in their bunks. Three more, who were playing cards at a plain deal table, glanced up from their game as the British lads passed by; but their interest was of brief duration, and stolidly they resumed their play.

Stooping down to avoid a large metal trough—the "house" for the for'ard 105-millimetre disappearing gun—Ross and his chum arrived at the ladder by which they were to gain the open air.

The hatch-cover was thrown back. For the first time during their captivity they made the discovery that it was night. Looking upwards, they could see a rectangle of dark sky twinkling with stars that, with the slight motion of the submarine, appeared to sway to and fro.

The cool night breeze fanned their heated foreheads as they gained the deck. For some time, coming suddenly from the glare of the electrically lighted interior, their eyes were blinded. They could see nothing but an indistinct blurr of star-lit, gently heaving water.

Gradually the sense of vision returned. They found themselves on the fore-deck of the unterseeboot. They had made up their minds to see a turtle-back deck with a narrow level platform in the centre; instead they found that the deck was almost flat and, in nautical parlance, flush, save where it was broken by the elongated conning-tower topped by the twin periscopes and slender wireless mast.

Lying on the deck in all conceivable attitudes were most of the U-boat's crew, taking advantage of a brief spell on the surface to breathe deeply of the ozone-laden atmosphere.

Not a light was visible on board. Even the hatchway by which the lads had gained the deck was constructed to trap any stray beam from the brilliant glare below.

Miles away, and low down upon the horizon, a white light blinked solemnly; then after a brief interval it was succeeded by a red gleam. This in turn was followed by white again.

Trefusis, with a sailor's inborn instinct, began to count the intervals. Although having no means of consulting the only time-recording watch in the possession of the two captives, he had a fair idea of counting seconds. At fourteen from the disappearance of the red light the white appeared. An almost identical space of time occurred before the red reappeared.

"It's the Wolf Light," mentally ejaculated the lad.

His next step was to fix the bearing of the lighthouse. This he did by looking for the Great Bear, and then, following the Pointers, the North Star.

"Phew!" he muttered softly. "Nor'-nor'-west. This brute of a submarine is right in the chops of the Channel—the main highway for vessels making for London and the south coast ports."

"What's that?" asked Vernon, who heard his chum speaking, but had failed to grasp the significance of his words.

"Nothing," replied Ross almost in a whisper. "I'll tell you later."

The cool air had revived both lads wonderfully. They had been left to their own devices, for the petty officer had gone aft. Those of the crew who were on deck seemed as apathetic as the men below concerning the presence of the kidnapped youths. They looked like men utterly worn out by fatigue and nervous strain.

Grasping the flexible wire hand-rail Ross continued his survey of the horizon, all of which was visible except a small portion obscured by the rise of the conning-tower. The air was remarkably clear. Taking into consideration the refraction of the atmosphere, the navigation lamps of a vessel shown at twenty feet above the sea would be visible from the low-lying deck of the submarine at a distance of six to seven miles.

But there were no signs of any vessels in the vicinity. The German submarine rolled lazily in complete isolation, waiting, like a snake in the grass, for its prey.

"Herr Kapitan would see you," exclaimed the guttural voice of the petty officer. "Come aft. Remember, when you are addressed, to remove your caps."

The man led the way, making no attempt to avoid the recumbent limbs and bodies of the crew who impeded his passage. Treading with discretion Ross and Vernon followed till, after skirting the base of the conning-tower, they found themselves in the presence of Lieutenant-Commander Schwalbe, the Kapitan of U75.

Schwalbe was sitting in a small arm-chair which had been brought from his cabin. He was smoking a cigar. At his elbow stood his satellite, Hermann Rix, who was also smoking. This luxury was denied the crew, the officers being permitted to smoke only when the submarine was running awash or resting on the surface.

[Illustration: THE INTERVIEW WITH THE GERMAN CAPTAIN (missing from book)]

"So you have recovered from your little involuntary rest," exclaimed Schwalbe in excellent English. He was a remarkably good linguist, for previous to the outbreak of the war he had been the skipper of a North-German-Lloyd boat. By sheer good luck he had reached a home port the day after the momentous declaration of hostilities, having narrowly escaped capture by a British destroyer.

Owing to the great expansion of the German submarine service, and its equally rapid reduction at the hands of the British Navy, the supply of specially trained officers of the Imperial Navy for this branch had run out. More had been transferred from the pent-up High Seas Fleet, while others had been absorbed from the now useless German Mercantile Marine, and hastily put through a course of instruction. Schwalbe was one of these, and after less than two months' hazardous work in the capacity of Unter-leutnant found himself in command of U75, one of the "last words" of von Tirpitz's piratical fleet.

Neither Ross nor Vernon replied. They could form no suitable answer. It was no doubt very considerate on the part of the Kapitan to enquire after their healths, but somehow the lads felt that the skipper of U75 was responsible for their presence on board.

"Come, come," continued Schwalbe. "Don't be sulky."

"We are not," expostulated Ross.

"I'm glad to hear it," rejoined the Kapitan, with a grin that had the effect of letting his cigar fall to the deck. He stooped to retrieve it, but, suddenly remembering that it was beneath his dignity, changed his mind and kicked the glowing stump on one side. Having taken another from a gun-metal case, he lit it with a device that merely smouldered instead of giving a bright light.

"It is as well we understand each other," he continued. "Do you know why you are on board U75?"

"No, sir," replied Ross.

"Neither do I," rejoined Schwalbe with astonishing candour. "I wish I had not been honoured with your company."

"The remedy is in your hands then, sir," said Trefusis. "You can land us the next time you put in at St. Mena's Island for petrol, or else put us on board the first fishing craft we fall in with."

"I beg to differ," was the rejoinder. "Unfortunately you are on board, and you must make the best of it, I understand from my friend—shall I say Dr. Ramblethorne—that you are both very inquisitive. Inquisitiveness is a bad trait in ones so young. You see, it has got you into trouble. The doctor has strong reasons for getting me to take care of you for some considerable time, so you will have an opportunity of seeing how we Germans make war. No half-measures, mark you. It is useless to make war with a velvet glove. You English people call us pirates, I believe?"

"It certainly looks like piracy when German submarines sink harmless merchantmen without warning," declared Vernon.

"For my part I have never sent a merchant vessel to the bottom without warning," said Schwalbe. "As a seaman I regret having to sink any ship of commerce. As an officer of the German Navy I have to obey orders unquestionably. Nevertheless I have always given the crews of British ships a chance of escape, and have never sunk any vessel until the men are safely in the boats, unless she attempts to show fight or to run away."

"Would you blame a skipper for trying to save his ship?" asked Ross.

"You do not understand," exclaimed Schwalbe. "We are at war. A blockade has been declared upon the British Islands. If, after full warning, merchantmen persist in taking the risk, it is their look-out, not mine. However, to return to a more personal matter: having been saddled with you, I must endure your presence. You will be well fed, as far as the resources at our command will allow. You will be free to go wherever you wish on board, with the exception of the conning-tower, motor- and torpedo-rooms. I am not ungrateful, for my brother, who had the misfortune to be in the Ariadne, was captured by your fleet. He is being well treated somewhere in England. Hence I give privileges to the son of Admiral Trefusis and the son of Commander Haye so long as they are my compulsory guests. But bear in mind: you will be watched. Should you commit any fault, however slight, you will pay dearly for it. If you are foolish enough to attempt any act of treachery, death will be the penalty. Have I made myself perfectly clear?"

"Yes, sir," replied both lads.

"Very well. Is there anything you would like me to do within the bounds of reason?"

"Could we communicate with our parents?" asked Ross.

"No," replied Schwalbe decisively. "There are strong objections. And, while I am on the subject, should you fall in with the crews of destroyed ships you are strictly forbidden to communicate with them either by word or gesture. That will be a punishable offence of the second degree. Anything more?"

"My friend has had a nasty knock on the head," said Trefusis. "Have you a doctor on board?"

Again Kapitan Schwalbe smiled broadly.

"No," he replied. "There is no need. Cases of illness must wait till we return to port. The only injuries we are likely to sustain would put us beyond all medical aid. But several of the men are fairly skilled in rough surgery, so I will——"

"Vessel on the port bow, sir; she's showing no lights," announced a voice.

"All hands to stations!" ordered the skipper.

"Down below with you!" hissed the petty officer, who during the interview had stood rigidly at attention at two paces to the rear of his charges.

Already the hitherto recumbent men were alert. Quickly, yet in order, they disappeared down the fore hatchway, and amongst them were Ross and Vernon.

The officers had taken their places inside the shelter of the conning-tower. Everything was battened down from within, and with a gentle purr the electric motors were set in motion, while at the same time water ballast was admitted into the trimming-tanks.

Swift and stealthy had been their preparations, but the presence of the submarine was betrayed by the phosphorescent swirl of the water caused by the churning of the twin propellers as she slipped beneath the surface.

Twenty seconds later a swift vessel that looked suspiciously like a trawler, although her speed belied her, tore over the place where U75 had disappeared. Bare inches only separated the top of the latter's conning-tower from the massive keel plates of the craft that had all but accomplished its mission.

The watch-dogs of the British Navy were at work.

CHAPTER VI

The Tramp

Like a startled hare the unterseeboot fled for shelter. Not until she reached a depth of fifteen fathoms did she check her diagonally downward course. At intervals a dull booming, audible above the rattle of the motors, proclaimed the unpleasant fact that her antagonist was circling around the spot marked by the phosphorescent swirl and the iridescence of escaped oil, and was firing explosive grapnels in the hope of ripping open the U-boat's hull.

Kapitan Schwalbe, looking very grey in the artificial light, was standing behind the quartermaster. His hands were clenched in momentary apprehension. Beads of perspiration stood out upon his forehead. He was experiencing a foretaste of the torment of the lost.

As a submarine officer of the Imperial German Navy he was a failure. Only sheer luck had hitherto saved him from the fate that had overtaken scores of his brother officers in that branch of the service. Skilled as he was in the handling of a huge liner, he lacked the iron nerve that is essential to the man who has to risk his life in a steel box that, in ninety-nine cases out of a hundred, offers no means of escape in the event of a catastrophe.

Yet he had to do his duty, notwithstanding his utter distaste for submarine work. He had had no option. The officers of the British Navy volunteer for submarine duties; those of the German Navy are simply told off whether they want to or not.

The nerve-racking work was beginning to tell upon him. His orders condemned him to a forlorn hope, for the English Channel was known to be a death-trap for the under-sea blockaders. The sight of a trawler filled him with feelings akin to terror. The possibility, nay probability, of a merchantman carrying guns made him approach his intended prey with the utmost caution; yet, as he had remarked to Ross Trefusis, he had never torpedoed any vessel flying the red ensign without giving her warning.

But it was not chivalry that prompted Schwalbe to act with consideration. Had he been untrammelled he would have sent his prey to the bottom without compunction, for he had all the brutal instincts of the kultured Hun. It was a superstitious fear that held his frightfulness in check—a presentiment based upon the Mosaic Law, an eye for an eye and a tooth for a tooth.

Having placed a considerable distance between him and his attacker, Kapitan Schwalbe ordered the electric motors to be stopped. The ballast tanks were "blown", and cautiously U75 rose to the surface.

It was the best course open to her. The depth of the water was much too great to allow her to rest on the bed of the sea. On the other hand, in order to keep submerged, the motors would have to be in motion. No one knew better than Schwalbe that the British patrol-boats would be in a position to locate with uncanny certitude the presence of their quarry, unless the strictest silence were maintained by the fugitive.

So, ready to dive at the first alarm, U75 floated awash until such times as were considered favourable for getting under way. Decidedly this part of the English Channel was, for the time being at least, unhealthy; and Kapitan Schwalbe resolved to make for the Bristol Channel, where the dangers of being destroyed by modern mosquitoes were more remote.

Meanwhile Ross and Vernon had been sent back to the quarters in the alley-way, by the side of the motor-room. Not knowing the reason for the U-boat's sudden submergence, and consequently unaware of the danger that threatened her, they formed the erroneous impression that the submarine was about to attack.

"The old fellow gave us a pretty straight tip," remarked Vernon, when the chums found themselves alone. "All the same, I vote we get out of it at the first opportunity, favourable or otherwise."

"'Ssh," whispered Ross. "Someone might be listening. I don't see how you propose to clear out, though."

"We were on deck just now."

"We were," agreed Trefusis.

"It was fairly dark. All the men up for'ard were lying down. It would have been an easy matter to have dived overboard and swum for it, if we hadn't been twenty miles or more from land."

"There was a bright look-out kept, all the same," objected Ross. "And I wouldn't mind saying that if the submarine were closer inshore, getting a supply of petrol, for example, we should be closely watched. All the same, I'm with you if we get the ghost of a chance. But it's a rummy affair altogether. Fancy that chap knowing our names and the rank of our respective fathers."

"Ramblethorne must have told him that," said Vernon.

"I suppose so; but for what reason? By Jove, if we get out of this mess all right, we'll have something to talk about—having been prisoners on a German submarine!"

The lads were not allowed on deck again that night. Acting upon Haye's suggestion they "turned in", and slept fitfully until awakened by the noise of the watch being relieved.

The seaman, Hans Koppe, brought them their breakfast. The meal consisted of fish, coffee, and the usual black bread. By this time the captives had practically recovered from the effects of the injection. Haye's head was still painful, although the headache had left him.

They ate with avidity, owing possibly to the atmosphere of the confined space, which was highly charged with oxygen.

"What is the Captain's name?" asked Ross, when the man came to remove the breakfast things.

The sailor told him.

"Where are we now?" enquired Vernon.

The man winked solemnly.

"Afloat," he replied. "Be content with that."

Just then there were unmistakable signs of activity on the part of the submarine crew. Several men hurried along the alley-way, each with a set purpose. They paid little heed to the Englanders as they passed.

At their heels came Herr Rix, the Leutnant of the submarine. He was beaming affably.

"Goot mornings!" he exclaimed. "You come mit me, den I show you how we blockade."

He led the way to the compartment in which the bowl of the supplementary periscope was placed. It was now broad daylight, and consequently the bowl showed a distinct image. A junior officer was standing by, but on seeing Rix approach he saluted and moved aside.

"Look!" exclaimed the Leutnant.

Both lads peered into the bowl. On its dull sides, an expanse of sea and sky was portrayed. Beyond that they could see nothing, until Rix called their attention to a small dark object.

"Englische sheep!" he declared. "Now you vos watch."

He touched a metal stud. Instantly an arrangement of telescopic lenses came into play within the tube of the periscope, with the result that a small portion of the view was greatly magnified upon the object card. It revealed a tramp of about nine hundred tons. She had a single funnel painted black, with two broad red bands; two stumpy masts, with derricks, and a lofty bridge and chart-house abaft the funnel. She was wall-sided. Her rusty hull was originally painted black. Here and there were squares of red lead, showing that her crew had been engaged in trying to smarten her up before she reached port. Aft, frayed and dirty with the smoke that poured from her funnel, floated the red ensign.

The submarine began to rise. Although she tilted abruptly, the image of the tramp steamer still remained upon the object bowl. By an ingenious arrangement, the lenses were constructed to compensate for any deviation of the tube of the periscope from the vertical. The lads could see the bows of the U-boat shaking clear of the water, throwing cascades of foam off on either side as the passing craft forged ahead at at least eighteen knots.

Now, for the first time, the skipper of the tramp saw the danger. He was a short, thick-set man, with white hair and an iron-grey moustache, and a face the colour of mahogany. For an instant he grasped the bridge-rails and looked towards the submarine, then gesticulated violently to the man at the wheel.

The spikes ran through the helmsman's hands, as he rapidly revolved the wheel actuating the steam steering-gear. The tramp swung hard to port, with the idea of baffling the momentarily expected torpedo.

Kapitan Schwalbe acted up to his principles. In any case he was loath to use a torpedo upon a comparatively small vessel. In response to an order, half a dozen of the submarine's crew swarmed on deck, three going for'ard and three aft. Within forty-five seconds the two disappearing guns were raised from the water-tight "houses".

Ross, Vernon, and the German Leutnant remained gazing into the bowl of the periscope. The vision so absorbed the attention of the two lads that they hardly heeded the presence of Herr Rix, who occasionally emitted grunts of satisfaction or annoyance as the scene was enacted.

The bow gun spat viciously. The range was but three hundred yards. The missile passed a few feet in front of the tramp's bows, and, throwing up a shower of spray that burst inboard on the British vessel's fo'c'sle, ricochetted a mile or so away.

The tramp's skipper showed his mettle. Round swung the vessel, listing heavily as she did so. By this time the call for more steam had been responded to, and dense clouds of black smoke belched from her funnel, mingled with puffs of white vapour as the siren bleated loudly for aid.

Running awash, U75 had a great advantage of speed; overtaking her prey she was able to send half a dozen shells into the lofty target presented as she slid by.

Holes gaped in the thin plating close to the waterline. A shell, passing completely through the funnel, demolished the siren. Being without wireless, the tramp was now without means of long-distance signalling.

Another missile hit the chart-house and, exploding, swept the frail structure overboard in a thousand fragments. The old skipper, hit by a splinter of wood, fell inertly upon the bridge; but the next instant he staggered to his feet, bawling to the crew to get the hand-steering gear connected.

"He's down again!" exclaimed Ross breathlessly, as the brave old man dropped upon the shattered planking of the bridge. "Hurrah! He's still alive."

The skipper had deliberately taken cover behind the slender shelter afforded by the metal side-light boards. By the frantic movement of his arm, it was evident that he was exhorting his men to "stick it" like Britons.

The hail of shells continued. Already fire had broken out on board in several places. A sliver of metal sheered through the ensign staff. Without hesitation one of the crew rushed off, retrieved the weather-worn bunting, and made his way to the mainmast.

Slowly and deliberately he re-hoisted the ensign until it fluttered proudly from the truck, then with apparent unconcern the man disappeared below.

By this time the tramp was again under control, with a course shaped for land, which lay about ten miles to the S.S.E. It was, however, a foregone conclusion that unless help were speedily forthcoming the vessel was doomed.

The tramp began to heel, almost imperceptibly at first, then with increasing speed. She had received her coup de grâce.

Still the engines were kept going full speed ahead. The dauntless skipper remained on the bridge, with a look of grim resolution on his weather-beaten features.

Slowly the vessel's way diminished. Her bow-wave, owing to the gradually increasing draught, was greater, but less sharp than before. In a few minutes the water would be pouring over her fore-deck.

Seeing that their work was completed, the pirates ceased fire, the guns' crews standing with folded arms and stolidly watching the tramp as she struggled in her death-throes.

Presently a vast cloud of steam issued from her engine-room. The inrush of water had damped her furnaces. The engineer and firemen, their faces black with coal-dust and streaming with moisture, hurried on deck.

For another quarter of a mile the doomed vessel carried way, then came to a sudden stop. As she did so she gave a quick list to starboard, until only a few inches of bulwark amidships showed above the waves.

Then, and only then, did the skipper give orders for the boats to be lowered. In an orderly manner the crew manned the falls, and the task of abandoning the ship began.

Without undue haste, the crew dropped into the waiting boats, each man with a bundle containing his scanty personal effects wrapped up in a handkerchief. The Captain was the last to leave. He did so reluctantly, his left hand tightly grasping the ship's papers.

Having rowed a safe distance from the foundering vessel, the men rested on their oars, and waited in silence for the end. It was not long in coming.

The tramp was heeling more and more, and slightly down by the bows. Suddenly she almost righted; then, amid a smother of foam as the compressed air burst open her hatches, she flung her stern high in the air.

Even then she seemed in no hurry. The after part from the mainmast remained in view, the now motionless propeller being well clear of the water.

For quite a minute she remained thus, then with a quick yet almost gentle movement slid under the waves. The last seen of her was the weather-worn red ensign still fluttering from the truck.

The periscope's bowl showed nothing but an expanse of sea and sky, and the two boats rising buoyantly to the waves.

A grim chuckle brought Ross and Vernon back to their surroundings. Herr Rix was rubbing his hands and grunting with evident satisfaction.

"Goot!" he ejaculated. "Now, how you like dat? Now you see how we German make blockade, hein?"

"A brave deed," replied Ross scornfully, and, gripping Vernon by the arm, led him back to their uncomfortable quarters in the alley-way.

CHAPTER VII

On the Bed of the Sea

For the next twenty-four hours nothing exciting occurred. The U-boat kept to the surface as much as possible, running under her petrol motors at fifteen knots. To exceed that pace would mean too great a consumption of fuel, and already the vessel was short of petrol.

Kapitan Schwalbe was prone to act on the side of extreme caution. Having sunk one vessel, he would not tackle another in the same vicinity. He invariably put at least a hundred miles between him and the scene of his latest ignominious exploit before attempting another act of kultur.

Three times during that twenty-four hours he dived: twice on sighting what were unquestionably Bristol Channel pilot-boats, and on the third occasion when a Penzance lugger under motor-power (for it was a dead calm) crossed his track.

All this time a regular stream of shipping was passing up and down the Bristol Channel, as unconcernedly as in the piping days of peace. To anyone but a bumptious German, the sight would have told its own tale; for the British Mercantile Marine, used to danger and difficulties, was not to be deterred by the "frightfulness" of von Tirpitz's blockade. On the contrary, the possibility of falling in with a hostile submarine gave an unwonted spice to the everyday routine of the toilers of the sea.

After breakfast on the following morning Ross and Vernon were told to go on deck. The sea was still calm, and the submarine, now running awash at full speed, was cleaving the water with practically dry decks.

The lads soon realized what was in progress. A couple of miles away was a large ocean cargo-boat, outward bound, and U75 was in pursuit.

Trefusis and his chum were not allowed for'ard, where the quick-firer was already in position for opening fire. They were ordered abaft the conning-tower, the hatch of which was open.

Kapitan Schwalbe's head and shoulders could be seen projecting above the opening. On the raised grating surrounding the conning-tower, stood a boyish-looking Unter-leutnant. Hermann Rix was nowhere to be seen. Apparently his duties compelled him to remain below.

Presently the quick-firer barked, and a projectile struck the water about a hundred yards from the starboard side of the pursued vessel. With the discharge of the gun, a sailor hoisted the black cross ensign of Germany from a small flagstaff aft, while a signal in the International Code ordering the British vessel to heave to instantly fluttered from the light mast immediately abaft the conning-tower.

The only response from the chase was the hoisting of the red ensign, for previously she had shown no colours. Slowly, defiantly, the bunting was hauled close up, and ironically "dipped" three times.

Again and again the submarine's bow-chaser fired. The shells were well aimed as regards direction, but all fell short. Imperceptibly the merchantman had increased distance.

"Look at the fools!" Ross heard the Kapitan remark, as he kept his binoculars focused on his intended prey. "They are trying to snapshot us. Are all Englishmen so blind to peril?"

"Are you sure they haven't a couple of quick-firers mounted aft, sir?" asked the Unter-leutnant. "There are several men gathered round something on the poop."

"Himmel, I hope not!" ejaculated Schwalbe. "But no; had they any guns they would have opened fire before now. What is the matter with our gun-layer? It is about time he got a shell home."

The Unter-leutnant lowered himself on the foredeck, and shouted angrily at the seaman whose duty it was to "lay" the bow-chasers. The man again bent over the sights.

This time the shell pitched ahead of the chase, but slightly to port. Some of the spray thrown up by the projectile fell on board.

"Is that the best you can do, you brainless idiot?" shouted Schwalbe wrathfully. Now that he was in pursuit he was loath to be baffled, but at the same time he realized that the submarine was using a lot of precious fuel and a prodigious amount of ammunition without any definite result.

In the midst of his torrent of abuse directed upon the luckless gun-layer, Kapitan Schwalbe suddenly stopped. Gripping the rim of the oval hatchway he gazed, horror-stricken, at two objects bobbing in the water directly in the path of the submarine. Then, recovering his voice, he shouted to the quartermaster to port helm.

The fellow obeyed promptly, but it was too late. Practically simultaneously, two barrels swung round and crashed alongside the submarine's hull.

Officers and men, expecting momentarily to find themselves blown into the air, stood stock-still. Then, as nothing so disastrous occurred, Schwalbe gave orders for easy astern.

The barrels, connected by a span of grass rope, had been thrown overboard from the pursued vessel, in the hope that the submarine would foul her propellers in the tangle of line. Once a blade picked up that trailing rope, the latter would coil round the boss as tightly as a band of flexible steel.

The plan all but succeeded; only the metal guards protecting the propellers saved them from being hopelessly jammed. Yet the attempt was attended with good results as far as the British ship was concerned, for by the time U75 had lost way and had cautiously backed away from the obstruction, the swift cargo-vessel had gained a distance that put her beyond all chance of being overhauled.

Infuriated by his failure, Kapitan Schwalbe went aft and descended into his cabin. He was hardly conscious of the presence of his two involuntary guests as he passed. He was thinking of the fate that had consigned him to a perilous and uncongenial task. Without doubt the vessel he had been pursuing was equipped with wireless, and by this time a number of those dreaded hornets would be tearing towards the spot. To add to his discomfiture it was reported to him that the reserve of fuel on board had seriously dwindled. In order to remain effective it was necessary that U75 should replenish her tanks before another forty-eight hours had passed.

According to his customary tactics, Schwalbe ordered the submarine to dive to sixty feet. At that depth she would be safe from any possibility of being rammed. Provided she could avoid the under-water obstructions with which the British naval authorities had sown the bed of the sea at almost every point likely to be frequented by lurking hostile submarines, she was in no actual danger.

Gaining his diminutive cabin, Schwalbe by sheer force of habit consulted the aneroid. The mercury was falling rapidly. Since he last looked, barely two hours previously, it had dropped 764 to 734 millimetres, or an inch and two-tenths. That meant that the anti-cyclone was rapidly breaking up, and that a severe gale was approaching with considerable swiftness.

U75 must submerge and seek shelter. It was impossible for her to keep at a uniform depth unless she maintained steerage-way; that meant a great demand upon her storage batteries. She could not remain on the bottom of the sea in a heavy gale, owing to the constant "pumping" or up-and-down movements caused by the varying pressure of passing waves, unless she sought a sheltered roadstead—and sheltered roadsteads were generally mined, or guarded by some ingenious device that had already accounted for several of U75's consorts.

Producing a chart of the Bristol Channel, Schwalbe unfolded and spread it upon a table. Then, in conjunction with a translation of the latest British Admiralty guide to the west coast of England, he proceeded to select what he hoped would be a snug shelter during the coming storm.

"Herr Rix!" he shouted. "I'll make for this anchorage. There's every indication of a strong blow from the nor'-east."

"This" was Helwick Channel, a deep, almost blind passage between the Glamorgan coast and an outlying submerged reef known as the East and West Helwick. In fine weather it was a short cut for traders plying between Llanelly and Swansea. In bad weather it was a place to be avoided, as far as sailing vessels were concerned. Sheltered by the bold outlines of Worm's Head, it ought to prove an ideal lurking-place until the gale had blown itself out, for there was little danger of the place being used as an anchorage, since vessels preferred to give the rock-bound coast a wide berth. On this account, it was also highly probable that the Helwick channel had not been safe-guarded by the British naval authorities.

Just before sunset, U75, having made the passage unobserved, brought up in twelve fathoms of water, resting evenly on the firm, hard sands at the bottom.

Ross and his chum turned in early. There was nothing for them to do. They held aloof from the crew; there were no books to entertain them, no games to amuse them. The submarine was now motionless, sufficient water ballast having been taken in to allow her to settle firmly upon the bottom; but, in order to be prepared, the anchor was let go. Thus not the slightest movement of the hull was apparent. The rest, after hours of erratic movement on the oily swell, was a welcome one.

The lads had set their joint watch by the submarine's time, which, being mid-European standard, was one hour fast of Greenwich.

For several hours they slept soundly and undisturbed. Suddenly they were both awakened by the muffled tramp of men in heavy sea-boots. The solitary light in the alley-way was switched off; the water-tight doors were firmly closed. Already the air in the confined space was stifling.

"What has happened?" asked Vernon anxiously, for the vessel, instead of resting immovably upon the bed of the channel, was now rolling sluggishly. Yet she could not be under way, for the motors were silent.

Springing from his bunk, Ross felt for the switch of the electric light. It was already down, yet the flow of current was interrupted.

"Let's find out," he said. "Come along."

The lads, before turning in, had carefully laid out their clothes, so as to be ready to slip into them at a moment's notice, yet it was a matter of considerable difficulty to dress in the dark.

"The door's closed," announced Ross as the lads groped their way to the end of the alley-way.

"I believe the submarine's holed," suggested Haye.

"No; she wouldn't lift as she's doing. Besides, the crew are moving about. Let's bang on the door with our boots."

For several minutes they hammered, but without result. The air, never very fresh, was now almost unbearable, owing to lack of ventilation. The imprisoned youths began to get desperate.

Then, without warning, the door slid back. The alley-way was flooded with brilliant light.

"Make haste!" shouted a voice which the lads recognized as that of Hans Koppe. At the same time he grasped Ross by the shoulder and literally dragged him across the steel threshold. Vernon followed quickly, but barely had he gained the compartment beyond than the massive steel door shot back again.

"Didn't you hear the order all hands for'ard?" asked Hans, not unkindly, for the white faces of the English lads told their own tale.

"No," replied Ross. "Besides, we are not included in the 'hands', are we?"

"You'll have to bear the consequences if you don't obey," rejoined Koppe. "I'm supposed to be looking after you, but how was I to know you hadn't turned out? Fortunately for you, I heard your knocking, and asked Herr Kapitan to open the doors. He was angry, but did so."

"What has happened then?" asked Trefusis, for the seaman seemed in a communicative mood.

"A shift of wind. It's blowing great guns up aloft, and there's a terrific tumble into this channel. We've dragged, or, rather, swung round our anchor."

"But we are safe enough?" asked Vernon.

"Yes, safe," replied Hans. "Too safe; we cannot break out our anchor. They are sending a diver to see what is amiss."

Evidently the diving arrangements on board were not considered to be of a confidential nature, for Hans led the way to the compartment under the fore-hatch, without the lads being sent back by the significant word "verboten".

A man was preparing for a submarine walk. He was already dressed in an india-rubber suit, with leaden weights attached to his chest, back, and boots. Two others were standing by, ready to place the helmet over his head, when Leutnant Rix had finished giving him minute directions.

The officer spoke rapidly and in a low tone. Ross could not catch all he said, but the words "gefährliche Strömungen" (dangerous currents) and "Der Wendepunkt der Flut" (slack water) and "Drei Viertel funf" (a quarter to five) occurred frequently.

Vernon glanced at his watch. It was then a minute after four. Apparently Rix was impressing upon the man that he must clear the anchor at slack water, which occurred at a quarter to five.

The two attendants then proceeded to place the diver's helmet on his head. The lads noticed that it had neither air-tube nor telephone wire. Nor was there a life-line attached to his waist. Fresh air was obtained from a metal case strapped to his back. The man was able to work independently, and without having to rely upon his air supply from the submarine.

The oval door in the diving-chamber was thrown open. The diver entered, and the water-tight panel was quickly replaced. One of the seamen thrust over a short lever, and immediately water rushed into the small compartment. As soon as the space was filled the diver was able to open a similar door in the outer plating of the submarine, and thus gain the bed of the sea.

Presently Leutnant Rix turned, and saw for the first time that Ross and Vernon were discreetly standing in the background.

"Go away. It is forbidden!" he shouted angrily.

They obeyed promptly, retreating to the space allotted to the crew, since it was neither desirable nor possible to return to their bunks.

For some minutes the luckless Hans Koppe was subjected to a severe dressing-down by his hot-headed officer, and when at length the seaman rejoined the lads he was in no humour to resume conversation.

Slowly the minutes sped. The submarine was still rolling sluggishly, in spite of the fact that more water had been admitted into the ballast tanks.

The men were talking seriously amongst themselves. From scraps of conversation that drifted to the lads' ears, it was evident that they had grave doubts concerning the ability of the diver to perform his task, and even of his chances of regaining the submarine, owing to the violent disturbances of the water.

Presently the motion of the anchored submarine became more acute. A weird grating sound—the noise made by the hull rasping over the bed of the sea—was distinctly audible.

One of the seamen produced a pocket compass. His startled exclamation brought other members of the crew around him. The magnetic needle was apparently describing a semicircle. U75 was swinging round her anchor.

Just then a bell tinkled, and a disc oscillated on the indicator board on the bulkhead. Instantly the two men who had been told off as attendants upon the diver hurried aft, while their companions crowded expectantly around the door.

The two men came back, staggering under the weight of the diver. They had already removed his head-dress and leaden weights. Water dropped from his rubber suit. His face was livid, his eyes wide open and rolling. One of his bare hands was streaked with blood that flowed sullenly from a cut in his numbed flesh.

Kapitan Schwalbe and Leutnant Rix followed him into the crew-space. It was not through feelings of compassion that they had come for'ard. It was acute anxiety to hear the diver's report.

The luckless man was laid upon the mess-table. His attendants divested him of his diving-suit, and rubbed his body with rough towels. A petty officer poured half a glass of brandy down his throat.

"What is amiss?" Kapitan Schwalbe kept on repeating.

With a great effort the diver sat up.

"An anchor, sir," he gasped feebly. "An anchor—an English naval pattern one—has been dropped right over ours. A very big one."

Then his eyes closed, and he fell back unconscious.

"Gott in Himmel!" ejaculated Rix. "We are trapped!"

CHAPTER VIII

Balked by a Sea-plane

"How so?" demanded Kapitan Schwalbe. "If we keep quiet, the cruiser—for cruiser she must be, judging by the fellow's description—will weigh and proceed."

"When she does weigh we are undone," said Rix despondently. "We are swinging round our anchor. For all we know, our cable has taken a turn round hers. As soon as they heave up their anchor, our anchor and cable will be brought up with it, and then the game is up. Either the strain will overcome our dead weight and we will be hauled to the surface, or else they'll lower one of their brutal explosive charges."

"The situation is serious," admitted Schwalbe in a low tone, for his Leutnant's words had produced a demoralizing effect upon the men. "How much cable have we inboard?"

Rix repeated the question. A petty officer doubled forward to consult the cable indicator. U75's anchor, when under way, was housed in a trough on the under side of the submarine's forefoot. The cable was automatically ranged in a compartment between the inner and outer skins, the space being always filled with water. The inboard end of the cable was not shackled; but to prevent its being able to take charge and run out, an indicator was placed on the bulkhead nearest to the cable tier. The amount of chain let go was regulated by a compressor, which was actuated from within the hull by means of levers and cranks, watertight glands being provided to prevent any leakage into the interior of the submarine.

"Seventy-five fathoms," reported the petty officer. "When we commenced to swing we paid out the length we had taken on board when we hove short."

"We must sacrifice the lot, Herr Rix," decided Kapitan Schwalbe. "There is no time to lose. Storm or no storm, we must slip and run for it."

It was U75's only chance, but it left her with only a small stockless kedge-anchor and chain, insufficient to withstand a heavy strain.

The compressor was released. With a loud rumble, for every sound was magnified within the confined space, the rest of the cable was allowed to take charge. It did so promptly, the end of the chain giving the hull a defiant smack as it did so. U75, no longer held by her anchor, began to drift with the tide, scraping dismally over the bed of Helwich Channel.

Schwalbe was now back at his post in the conning-tower. He dare not take the submarine to the surface until he had put a safe distance between him and the anchored British warship. Nor did he care to order the ballast tanks to be blown. Rather than allow the "pumping" of the seas to hammer the submerged craft upon the hard sand, he preferred to take the risk of letting her drag.

Fortunately the tide set evenly along the bed of the channel. A cross-current would have set the submarine upon the jagged rocks of the hidden West Helwick Ridge. Nevertheless there was always the danger of being hurled violently against a detached rock, or of fouling a live mine if by chance the British had laid obstructions in the channel.

Both Ross and Vernon knew the danger, but, manfully concealing their misgivings, they watched the faces of those of the crew who were "watch below". Most of the men were Frisians, broad-shouldered, blonde-featured, and generally devoid of fear. Yet the ceaseless strain upon the nerves had already begun to tell. As hardy fishermen, they would not have hesitated to launch their open boats in a storm to go to the rescue of a hapless vessel aground on the grim sand-banks of the Frisian shore. As the conscript crew of the submarine, compelled to keep within the limits of a steel box that almost momentarily threatened to be their tomb, their natural bravery was quenched.

Many of them sat upon their lockers, stolid-faced men who had already tasted of the bitterness of death. Others showed unmistakable signs of excitement, bordering on frenzy. They dreaded their life of modern piracy. The idea of sinking hapless merchantmen was repugnant to them, for they understood the brotherhood of the sea. It would be different if they were called upon to attack an armed British ship of war. They had no option but to obey their junker officers, who in turn were compelled to accept the misguided orders of the arch-pirate, von Tirpitz.

They were disheartened, too, for reports, in spite of the vigilance of the officers to conceal them, had reached them of the losses inflicted upon other unterseebooten. Occasionally they heard of a submarine crew being saved, but generally it was a case of total loss of all on board, by some hitherto unknown means, at the hands of the British Navy.

A hand touched Ross lightly on the shoulder. Turning, he saw Hans Koppe standing in a darkened corner of the compartment.

"Can you tell me this, mein herr?" asked the seaman in a low tone. "Is it true that the English give no quarter to German seamen in submarines?"

"I shouldn't think that they would refuse to do so," replied Trefusis. "Of course, I can quite understand that an opportunity doesn't often occur; but I've heard of several instances in which your U-boats have surrendered, and the crews have been treated exactly the same as other prisoners of war."

"I have heard differently," said Hans, "but I hope it's a mistake. I have a feeling that we won't see Wilhelmshaven again. And I have a wife and six children at Flensburg. Our Kapitan, too, expects that we might be denied quarter, because we have sunk your merchantmen. Believe me, I regret having done so, but we have orders. Do you know why Kapitan Schwalbe took you on board?"

"Because a certain German agent wanted us out of the way, I suppose," replied Ross.

"Perhaps," admitted Hans Koppe. "But in the event of our being captured he thinks that his good treatment of you will be in his favour. We are, I do not mind telling you, in a very tight corner. Our fuel supply is almost run out. We cannot hope to return home by way of the Straits of Dover. Not one of our submarines has tried that passage of late without meeting with disaster—at least, so I heard der Kapitan tell der Leutnant. Ach! It is deplorable, this war."

The rapid ringing of a gong was the signal for the watch below to turn out. A peculiar hissing noise proclaimed the fact that the ballast tanks were being emptied. U75 no longer grated over the bottom; her motors were running almost dead slow.

Although submerged, the submarine was "pumping" violently. Seasoned men were prostrate with sea-sickness. The air, in spite of chemical purifiers, was becoming almost intolerable. Everything movable was being thrown about in utter disorder, while to add to the discomfort of the crew the covering-plates of one of the lubricating-oil tanks had been strained, and at every jerk jets of viscous fluid would squirt through the fracture and trickle sullenly over the floor of the crew-space.

Since the watertight doors were still closed, Ross and Vernon were unable to get back to their bunks. Feeling thoroughly wretched, they were glad to accept Hans Koppe's offer to lie down on a long locker.

At noon, U75 came to the surface. The storm, being short forecasted, had quickly blown itself out, but the waves still ran high.

It was a prearranged plan on the part of the three U-boats operating in the English and Bristol Channels to communicate with each other by wireless at noon and at midnight. U75's wireless had a range of about 180 miles, and although it could be "jammed", the call could not be tapped by vessels other than the one for which it was intended. To make doubly sure, the messages were sent in code.

For nearly ten minutes U75 "made her number" without eliciting any reply. Perhaps it was well that Kapitan Schwalbe did not know what had happened to her consorts. U74 was at that moment lying on her side at the bottom of a Welsh harbour, her crew poisoned by the chlorine fumes from her batteries—the result of a rash curiosity on the part of her Lieutenant-Commander to investigate the approaches to the anchorage. As for U77, she was flying blindly for safety, with a couple of destroyers hard on her track, and a naval sea-plane overhead to direct them in their search.

Foiled in her efforts to get in touch with her consorts, U75 remained awash. The heave of the sea made it most difficult for her to use her periscope with certainty, for she had chosen a bad pitch on her ascent—the furious "overfalls" or "tide-rips" to the west of Lundy Island.

"We'll pay another visit to St. Mena's Island, Herr Rix," decided Kapitan Schwalbe, after the two officers had discussed the sinister matter of their futile attempt to make use of the wireless. "To-night at nine o'clock ought to suit. If we cannot get von Ruhle to see our signals—for my own part, I doubt whether he is in these parts—we'll have to do our best to get ashore. Meanwhile, keep a bright look-out. If we see any likely vessel coming this way, we'll try our luck once more."

"Message just received, mein herr," announced the wireless operator.

"From whom?" enquired Kapitan Schwalbe eagerly. He was devoutly hoping that either U74 or U77 had been able to "call up".

"I cannot say, sir," replied the man as he handed a code message to his superior.

Decoded, the "wireless" was as follows:

"Station 41 to unterseebooten. Two hundred gallons of fuel available here. Will be on the look-out for signals at 1 a.m."

The message was a "general call" for a secret petrol depot to any German submarine operating in the vicinity. Reference to the list of stations showed that "41" was at Port Treherne, a remote cove on the North Cornish coast about fifty miles from St. Mena's Island.

"I suppose it's safe," remarked Rix.

"With due precautions—yes," rejoined Kapitan Schwalbe. "At any rate, petrol we must have. Where's the chart? Ah, there we are! It looks a fairly easy place to approach, don't you think? The only danger from a navigation point is apparently this ledge of rocks—Lost Chance Reef, it's called. What unpleasant names these Englishmen give to their coasts!"

At that moment the Unter-leutnant, who happened to be at the conning-tower periscope, reported that a large vessel was bearing down towards them.

Kapitan Schwalbe hurried to the conning-tower. The object depicted was that of a modern tank-vessel about four hundred feet in length. She was low in the water, showing that she was well laden. In place of masts she had four stumpy poles supporting derricks. Right aft was the single funnel. The navigation bridge was well for'ard, connected with another bridge just in front of the funnel by a long slender gangway.

"An oil-tank homeward bound!" exclaimed Kapitan Schwalbe. "Just what we want to fall in with. All being well, there will be no necessity to visit either Port Treherne or St. Mena's Island. Ach! When we have taken what we require we will set fire to the ship, and the English will have a splendid view of a maritime bonfire."

The crew were ordered to their stations, the ballast tanks "blown", and U75 rose to the surface instead of "running awash", since the Kapitan had resolved to stop the tank by gun-fire.

Even then the waves were running so high that the guns' crews were almost constantly up to their knees in water.

Somewhat to the surprise of the submarine's officers and crew, the tank-steamer made no attempt to escape. The firing of a shot across her bows and the display of the black cross ensign were enough to cause the skipper to reverse her engines.

In less than five minutes, the oil-vessel was rolling in the trough of the sea and drifting slowly to leeward. Yet it was a somewhat remarkable circumstance that no attempt was made to lower the red ensign that was proudly displayed at the stern.

Kapitan Schwalbe, with his intimate knowledge of navigation, knew that the only way possible to board the prize was to run to leeward of her, and let the hull of the large vessel serve as a breakwater. He also knew that the submarine would have to be constantly under way during the boarding operations, otherwise the tank-vessel, offering considerable resistance to the wind, would drift down upon U75, whose leeway was almost unappreciable.

"Send a boat, and lower your accommodation ladder," ordered Kapitan Schwalbe, who, as the submarine ranged up half a cable's length to leeward of the tank-vessel, had left the shelter of the conning-tower and was standing on the platform in its wake.

"Aye, aye," was the prompt response.

"Board her, Herr Rix," said the Leutnant's superior officer. "Bring back her papers with you. Order them to pump heavy oil both to windward and leeward. We will then be able to run close alongside and receive her hoses."

A boat containing two seamen and an apprentice was lowered from the tank's quarter and rowed to the submarine. Into it dropped Leutnant Rix and half a dozen armed men. With them they took two incendiary bombs fitted with time-fuses.

Rix smiled grimly as he gained the oil-steamer's deck. The captain and first mate were at the head of the accommodation ladder to receive him. Most of the crew were already mustering on deck, each with a bundle containing his private effects.

"You prize to German boat," announced the Leutnant. "Make you no trouble and we you will not harm. First we will haf much oil—petroleum, is it not? Order your engineer to get steam to donkey-engine, and your men—the—the—— Hein! Ach, I haf it—the hoses to get ready. When we fill up, then twenty minutes we give you to clear out. You onderstan'?"

"Perfectly," replied the British skipper, a tall, raw-boned Scot, as he eyed the podgy German Leutnant with grim contempt. "But d'ye ken yon?"

"'D'YE KEN YON?' ASKED THE BRITISH SKIPPER, AS HE EYED
THE PODGY GERMAN LEUTNANT WITH CONTEMPT"

He pointed skywards. Less than five hundred feet up, yet sufficiently far from the tank-vessel to enable the latter to screen her from the unterseeboot, was a large naval sea-plane. It was to deaden the noise of her motors that the ship's steam-pipe was continually blowing off steam from the time that U75 made her peremptory demand.

The eyes of the Leutnant and his six men followed the direction indicated by the British skipper's outstretched hand.

At that instant the sea-plane was visible above the towering sides of the British vessel.

U75 was still forging slowly ahead. In a trice Kapitan Schwalbe decided how to act. Ordering the men on deck to their diving stations, he dropped agilely into the conning-tower and gave the word for the helm to be ported.

Thus, while the quick-firers were being housed, the submarine had drawn close under the oil-tank's quarter. Here she was comparatively safe from the sea-plane, as the latter could not drop any bombs without risk of exploding the highly inflammable cargo of the British vessel.

In ten seconds the sea-plane was over and beyond her quarry. She had then to turn and circle overhead, awaiting the chance of shattering her enemy as she dived.

U75 was already disappearing beneath the waves.

She dived at a very oblique angle, steeper than she had ever done before.

Ross and Vernon, unaware of what was taking place, thought for a moment that the submarine was plunging headlong to the bed of the Bristol Channel. They had to cling desperately to the nearest object to hand to prevent themselves from sliding violently against a transverse bulkhead.

Even as they clung they heard two muffled detonations in quick succession, followed by a distinct quiver of the submarine's hull—a movement that bore a marked difference to the vibrations under the pulsations of the motors.

The sea-plane had dropped two bombs, both of which very nearly attained their object.

Kapitan Schwalbe did not bring the submarine to a horizontal position until she had reached a depth of fifteen fathoms. At that depth he was safe, both from explosives dropped from the sea-plane and also from observation. The water being still agitated, made it impossible for the observer on the biplane to follow the movements of a dark shadow fathoms deep. For once, the rough seas had been kind to U75; but the fact remained that she was still badly in want of fuel, while his last attempt had resulted in the loss of an officer and six men, who could not well be spared.

Although the sea-plane had failed to achieve her object by pulverizing the U-boat's hull, the moral and material result was none the less effective.

The explosion of the bombs had started several of U75's plates. Numerous jets of water were spurting through the seams, the inrush requiring all the mechanical appliances at the command of the modern pirate to keep the leaks under control, while the badly-jarred nerves of Kapitan Schwalbe and his crew warned them of the grave risks they ran in attempting to try conclusions with even an apparently harmless craft displaying the Red Ensign of Britain's Mercantile Marine.

CHAPTER IX

The Landing at Port Treherne

"I wonder if they'll let us go on deck," remarked Vernon Haye. "If so, I vote we have a shot at getting ashore. What sort of show is Port Treherne?"

"I know it fairly well," replied Ross. "It's the most forsaken crib you are ever likely to meet along the coast. It's a deep gully in the cliffs. There's only one small landing-place—a flat rock. Years ago there used to be a tramway down to the rock, and they shipped copper ore by means of derricks into lighters, which were towed across in fine weather to Swansea. But the mine closed down, the village is now deserted, and I don't believe there are any fishermen there. They say that the stream that flows into the port is still heavily charged with mundic. At all events the water is of a bright-red colour for several hundred yards from shore, and no fish will stick that."

It was close on the midnight following the disastrous attempt on the part of U75 to capture the oil-tank. The submarine was running awash, proceeding very slowly and cautiously towards Port Treherne—Station 41 of the secret petrol depots established by German agents along the coast of the British Islands.

The lads had been informed of the destination of the submarine, but had not been told why. Nevertheless it was an easy conjecture that U75 was going there to pick up stores that she had been unable to obtain in sufficient quantities at St. Mena's Island.

The Unter-leutnant was in charge of the submarine. Kapitan Schwalbe had taken the advantage of the opportunity of a few hours' sleep. Under-officered and undermanned, the strain on the personnel was a severe one. It was only on rare occasions that Schwalbe could in future descend from his post in the conning-tower.

At midnight, according to custom, the submarine called up her consorts by wireless. Judging by the previous attempt it seemed a useless task, but to the Operator's surprise he received a reply from U77, which was then lying off the Scillies.

Kapitan Schwalbe, aroused from his sleep, eagerly awaited the decoding of the message. It was to the effect that the commander of U77 had received information that H.M.S. Tremendous, one of the earlier Dreadnoughts, was leaving Gibraltar for Rosyth. The Tremendous, he knew, had been engaged in the Dardanelles operations. U77 therefore suggested that the two unterseebooten should meet at a rendezvous off The Lizard, and attempt a coup de main, the success of which would go towards atoning for the blunders and losses sustained by the German submarines in their endeavour to blockade the British Isles.

"Good!" exclaimed Kapitan Schwalbe. "Tell them that I purpose to rendezvous twenty kilometres S.W. by W. of The Lizard, on Thursday at 10 p.m. I am now about to take in fuel. Will communicate again at noon to-morrow. Ask them if they have picked up a wireless from U74."

Some time elapsed before the message could be coded by the sender and translated by the receiving submarine. When the reply confirming the rendezvous was received, a message was added to the effect that U77 had heard nothing of U74 for three days. It was presumed, however, that she was now on her way back to Wilhelmshaven, and was already out of wireless range.

Kapitan Schwalbe knew better. As senior officer of the three submarines detached to operate in these waters, he was aware that U74 would not have left her station without orders from him. That part of the message had been sent merely as a "blind", so that the crews of the remaining unterseebooten should not be discouraged. It was safe to conclude, decided Kapitan Schwalbe, that another of the blockaders had gone to the bottom for the last time.

It was close on one o'clock when the "wirelessing" terminated. U75, which had hitherto been running awash, was now trimmed for surface work.

Most of the crew went on deck. Amongst them were Ross and Vernon, no one offering any objection.

The sea was no longer rough. A long oily swell took the place of the white-crested wave. The night was dark. Only a few stars were visible. Away to the S.E., the black outlines of the Cornish coast reared themselves like an enormous wall against the gloomy sky.

Suddenly Vernon touched his chum's elbow, as a faint pin-prick of light glimmered twice. It was the shore agent's signal that the coast was clear.

Barely carrying steerage-way, U75 stood in towards the as yet invisible Port Treherne. Already her crew had brought the collapsible canvas boat from below, "man-handling" it through the fore hatch. The men, having opened it out and shipped the felt-lined and well-greased rowlocks, stood by to launch it.

Gradually the towering cliffs enclosing the creek became distinguishable against the loftier background of gaunt hills. Into the gap the submarine crept with the utmost caution, until it seemed as if she were on the point of running her nose against the sheer face of the granite wall. The water bubbled slightly as her motors were reversed; then, turning in her own length, she brought up, with her bows pointing seawards.

Three of the crew grasped the canvas boat and pushed it gently into the water on the port side. One of them clambered in and shipped the oars in the row-locks.

The two lads were cautiously scanning the shores of the inlet. Ross could sniff the unmistakable Cornish air. The call of home seemed irresistible. It looked a comparatively easy matter to slip quietly over the starboard side, and swim with noiseless strokes towards the weed-covered rocks that showed six feet or more above the sea. It was half ebb-tide; there was little or no drift out of the cove. Under the shadow of those dark cliffs detection seemed almost impossible, unless the submarine went to the risky expedient of switching on her search-light.

They moved stealthily towards the light wire railing on the starboard side just abaft the conning-tower. Everything seemed in their favour. Kapitan Schwalbe and the Unter-leutnant were on the navigation platform, peering through their night-glasses towards the flat rock that served as a landing-place. Two of the seamen were engaged in coiling down a hand-lead line; the rest of the men on deck were devoting their attention to the now departing canvas boat.

"Not so fast, my friends," exclaimed a low deep voice, which the lads recognized as that of Kapitan Schwalbe. "Remember I have a pistol ready to hand."

"How in the name of goodness did he know what we were up to?" thought Ross.

The chums stood stock-still. They felt much like children found out in some petty escapade.

"Koppe! Where are you?" asked the Kapitan in a loud whisper.

"Here, sir," replied the seaman.

"I hold you responsible for these Englishmen. Now they are trying to give us the slip. Take them below. But hold on. Secure them to a stanchion. Chain them up, and bring me the key."

The seaman approached the lads almost apologetically, and led them to the port side just for'ard of the conning-tower. A light steel chain was hitched round Ross's right ankle and Vernon's left, and deftly padlocked round one of the uprights supporting the hand-rail.

"It is of no use trying any of your pranks here," commented Kapitan Schwalbe, still in a low tone. "You are only looking for trouble."

For several moments all was still, save for the screech of a benighted gull. Overhead a meteor passed swiftly across the sky, throwing a pale gleam upon-the lurking submarine.

"Wer da?"

The words, although uttered in an undertone, travelled distinctly over the placid waters of the cove.

The sailor in the boat muttered some inaudible reply. The listeners in the submarine could detect the sound of his oars as he laid them across the thwarts. Then, after further conversation, could be heard the rumble of metal as the tins of petrol were rapidly placed in the boat.

"How many are there?" asked Kapitan Schwalbe eagerly as the men returned with the first load.

"Forty here, Herr Kapitan. Altogether there are over two hundred."

"Then be sharp and whip them on board. Was there any communication for me?"

"A bundle of English newspapers, sir, and this letter."

The man drew the documents from the inside of his jumper and passed them to a seaman, who in turn handed them to the skipper.

"I may have to land, sir," continued the seaman. "The rest of the cans are in a cove at some distance from the landing-place. Can Max go with me to mind the boat? There is a slight ground-swell at times, and she might have a hole through her canvas if she is allowed to grind against the rocks."

Receiving an affirmative reply, the man told his comrade to get on board, and once more the boat vanished into the darkness.

Another twenty minutes elapsed, then came the sounds of muffled footsteps, and of volatile spirit surging inside the petrol cans. Then one of the men must have slipped, for there was a slight scuffling, followed by the loud crash of a can clattering over the rocks.

"'Alt! Who goes there?" shouted a hoarse and unmistakably English voice.

"Freund," promptly replied the German sailor.

It would have been far wiser on his part if he had waited for his fellow-worker, the German agent, to reply, since his knowledge and pronunciation of English were almost perfect. But unfortunately it was the spy who had fallen, and, half-winded by coming in contact with one of the tins, was gasping for breath and at the same time rubbing a barked shin.

"Not good enough for me, old sport," rejoined the challenger, and without further ado he let loose "five rounds rapid".

A loud yell announced that one of the bullets had at least taken effect. It was the prostrate spy who received a dose of nickel through the fleshy part of his thigh.

The seaman, dropping his cans, fled for his life. Recklessly he leapt from the landing-place into the canvas boat, which his comrade had been keeping at oar's length from the shore. The sudden impetus was too much for the frail craft. She capsized, and, being only single-skinned, sank like a stone.

Already men, members of a picket, were hastening to the sentry's support, their progress marked by a lantern held by a stout and sleepy sergeant.

By this time U75 was making for the open sea. Kapitan Schwalbe was cursing loudly; not because the luckless agent had been hit—it was his fault for not making sure of his ground; not so much on account of the loss of two more men, nor of the sinking of the only boat belonging to the submarine. His anger was aroused at the knowledge that once again his efforts to obtain fuel had been balked. The quantity contained in forty tins was a mere fraction of the amount he required in order to carry out his ambitious programme. Bitterly he realized that, like those of transgressors, the ways of modern pirates are hard.

CHAPTER X

A Treacherous Plot

A ragged volley of musketry followed the departing submarine. One bullet mushroomed itself against the steel conning-tower; another zipped through one of the guard-rails. The rest either flew harmlessly overhead or ricochetted from the surface of the placid water.

Nevertheless the firing was a signal for the crew to hasten below. Kapitan Schwalbe and the Unter-leutnant disappeared with ignominious speed within the conning-tower. The men, bending low, bolted for the fore hatch. In twenty seconds the deck of U75 was deserted save for Ross and Vernon, who, padlocked to the stanchion, were unable to move six inches in either direction. They were only partly screened by the rise of the conning-tower. A sharp splinter from the bullet that had splayed against the steel wall cut cleanly through Vernon's coat sleeve and inflicted a slight gash in the lad's forearm, yet in the excitement he hardly noticed it.

"I say, old man," exclaimed Ross, as a wave slapping against the submarine's bow threw a shower of spray over the two prisoners. "What will happen if they submerge? It seems to me as if old Schwalbe has forgotten us."

"He would have dived before this if he intended so doing," replied Haye. "Ten to one he's going to pay us out for attempting to take French, or rather German, leave. It's jolly cold and mighty uncomfortable, but we'll keep a stiff upper lip and show him what we are made of."

"With all due deference to you, old chap," rejoined Trefusis, his teeth chattering as the keen wind played upon his saturated garments, "I would far rather be without this badge of German kultur." He indicated the chain that encircled his ankle. "I don't think that you can hold a brief for Kapitan Schwalbe. I am not so sure about it that he is not going to dive."

U75 dipped as he spoke, submerging her fore deck almost to the base of the conning-tower. Then, with a double cascade of water pouring from her, she shook herself free, throwing her bows high above the surface.

A man, gripping the stanchion-rail as he made his way knee-deep in water, came towards the two prisoners. It was Hans Koppe. He had obtained the Kapitan's permission to release his charges from their uncomfortable position.

"Hold on tightly as you go aft," he cautioned. "There is hot coffee waiting for you below."

It was impracticable to descend by means of the fore hatch. That means of communication had already been closed and battened down, owing to the constant flow of water over the bows. Even the after hatch, in spite of the protection afforded by the conning-tower and the raised coaming, was admitting water into the interior of the submarine.

Cold, exhausted, and hungry, the lads were glad to be able to eat and drink, discard their wringing-wet garments, and turn in. Without waking they slept solidly for ten hours. It was one in the afternoon when they turned out. U75 was rounding Land's End. She was submerged, steering a compass course, but frequently showing her periscope to ascertain her whereabouts. Already the Longships Lighthouse was broad on the port beam.

It was a tedious, discomforting run from Land's End to The Lizard. The Mounts Bay fishing fleets were out, a circumstance that compelled the submarine to keep below the surface. Kapitan Schwalbe knew that once the alert skippers of these boats sighted even the tip of the periscope, the news of the presence of a hostile submarine would be quickly sent to the naval authorities at Devonport. The necessity for secrecy also prevented him from making use of the wireless: not that the message would be deciphered, but because the origin of the message could be fixed with comparative certainty by any of the British wireless stations that "picked up" her call.

The approaches to Plymouth Sound, too, gave Kapitan Schwalbe a bad time. Far beyond the Eddystone, and from Looe Island to Bigbury Bay, armed trawlers and torpedo-boats patrolled incessantly, their movements aided by sea-planes. It was almost a matter of impossibility for a hostile submarine to approach Plymouth Sound by daylight, since the aeroplanes were able to discern any sinister object moving under the comparatively shallow and clear waters between Rame Head and Stoke Point; while at night the precautions taken were of such an elaborate and efficient description as to seal the fate of any submarine rash enough to run her head into a noose.

Accordingly U75 gave the Eddystone a wide berth, shaping a course to pass twenty miles to the south'ard of the far-famed lighthouse. Here she was in the thick of the Channel traffic, a stream of mercantile ships passing up and down as unconcernedly as if such a thing as a German submarine did not exist.

Although there were plenty of opportunities, Kapitan Schwalbe made no attempt to molest the ships. For one thing, experience had taught him that the British merchant skipper possessed a bull-dog tenacity, and a courage not to be daunted by the sight of a hostile periscope appearing from nowhere in the midst of a waste of water. For another, he was now on the look-out for more important game—his chance to retrieve his already vanishing prestige.

However, one of the merchant vessels served him a good purpose, although unknown to her. Marking a large ocean tramp bound up-Channel, U75 dived deeply, so as to be free from any danger of being hit by her forefoot.

With the noise of the tramp's propeller to guide her, U75 followed, unsuspected, in her wake as she made for the Lizard Light.

Arriving safely at the rendezvous, Kapitan Schwalbe waited until it was dark, and then cautiously brought the submarine awash. Punctually at ten o'clock a feeble violet light blinked through the night. It was U77's call to her consort.

"What's the game, I wonder?" asked Vernon, as a hail in German was borne faintly to their ears.

The chums had turned in. There was nothing else for them to do, since they had been ordered to leave the quarters allotted to the crew. As there was no furniture of any description in the alley-way that had been made their sleeping compartment, they had climbed into their bunks. Here they could maintain an almost uninterrupted conversation.

"Hist!" exclaimed Ross warningly. He had been lying with his ear almost touching one of the many voice-tubes that led from the conning-tower to various parts of the submarine. Quite by accident, he discovered that the pipes formed an excellent conductor of sound in a manner that had not been intended.

"What are you doing?" asked Haye curiously.

"Jam your ear against the centre one of these three pipes," said his chum.

Vernon did so. It required very little movement on his part, since the bunks were rather narrow. The same voice-tube that Ross was "tapping" ran vertically past Haye's bunk, which was immediately underneath the one Trefusis had appropriated from the time when he had been laid upon it under the influence of the injection.

This particular pipe formed a means of vocal communication between the conning-tower and Kapitan Schwalbe's cabin. For some reason the whistle had been removed from the cabin end, and consequently sounds from the Kapitan's quarters were conveyed with tolerable clearness.

There were two men engaged in conversation. One was Kapitan Schwalbe; the other, who spoke in a lower key, and so rapidly that Ross had great difficulty in mentally translating his words, was the Lieutenant-Commander of U77. He had been put aboard U75 only a few minutes previously.

"My dear von Hoffner," Kapitan Schwalbe was saying. "Your plan is all very well as far as you are concerned; but where do we come in? Understand that while we are on the surface our risks are increased ten-fold. Suppose, for instance, the battleship does not notice, or affects not to notice, the white flag?"

"She will, right enough," assured the Lieutenant-Commander of U77. "These English are such fools that in their anxiety to observe the rules of warfare" (here von Hoffner laughed sardonically) "they play into our hands. More than a twelvemonth of war has not taught them that the hitherto recognized observances of war are no longer binding. This is not a petty squabble between two nations. It is a struggle for existence; consequently it is where our frightfulness scores."

"It hasn't up to the present, according to my experience," objected Kapitan Schwalbe gloomily. "These Englishmen simply won't be frightened. But to return once more to the point: what steps do you propose to take to minimize my risk?"

"There must be risk, of course," remarked von Hoffner. "According to latest reports, it seems pretty certain that we cannot hope to intercept the Tremendous during the hours of darkness. Consequently we have to make use of a ruse. Directly I spot her I dive, keeping as much as possible close to her track, say three hundred metres off."

"Yes, you dive," commented Schwalbe caustically. "That is quite feasible. But what of U75?"

"She will keep on the surface almost exactly in the indicated path of the battleship. You will strike your ensign and hoist a large white flag in its place. It will mean scrapping your best tablecloth, mein herr. With the wind in its present quarter the flag will blow athwart the battleship's course, so there is no risk of it not being seen. You and your crew will, of course, form up aft. That will give more colour to the deception."

"Perhaps it will work," said Kapitan Schwalbe.

"Perhaps? Of course it will," declared von Hoffher sanguinely. "Then the rest is child's play. Directly the Tremendous slows down—it's the speed of these battleships that has caused us to miss hitherto—I will let loose two torpedoes. There will be no bungling, I assure you. I'll take good care to hit her close to the magazine, and there will be no opportunity for her to use her quick-firers.

"By the by, I've two English boys on board," said the Kapitan of U75. In a few words he related the circumstances in which they were made prisoners. "I suppose they ought to line up on deck with the hands?"

"Certainly," replied von Hoffher, with one of his cold-blooded sniggers. "It will heighten the illusion. It will do them good to see what one of our unterseebooten can do. But it is highly important that there be no survivors from the torpedoed battleship. The ruse is a grand one, and can be employed over and over again, provided that the secret does not leak out. After all, I don't think I would bring these English youths on deck."

"They are safe enough," protested Schwalbe. "If we return to Wilhelmshaven, they will be locked up in safe custody until the end of the war. If we do not, then I fancy there will be no survivors from U75 as well as from the English battleship Tremendous."

The two treacherous officers conversed in a similar strain for several minutes longer. Then came the sound of glasses being clinked as an accompaniment to a boastful toast. Talking boisterously, the two officers left the cabin, and presently the lads heard the sound of oars as von Hoffner was rowed back to his command.

CHAPTER XI

Preparations

"The brutes!" ejaculated Vernon savagely. He was violently excited. Perspiration was pouring off his face at the thought of the almost unparalleled act of wanton treachery that was about to be enacted. "If we could only prevent them!"

"I can't see how," rejoined Ross gloomily. "We cannot give an alarm. If we could control the valves for half a minute, I'd sink this blessed craft with all on board, myself included, for good and all. But it is no use talking of the impossibly heroic."

"I have a plan," announced Vernon, after thinking deeply for a few minutes.

"Well, out with it!"

"We have to pass through one of the broadside torpedo-rooms as we go on deck. We could each snatch a spanner and give the war-heads a terrific blow. You'll remember that there are half a dozen torpedoes in the cages against the bulkhead. It would mean certain death for us, but it would save nearly a thousand lives."

Ross shook his head.

"There's no certainty of success," he objected. "Those torpedoes are very much like our own Whiteheads. The striker in the head is protected against accidental discharge by a small propeller. Until the torpedo travels a certain distance through the water—sufficient for the resistance against the blades to cause the safety device to unthread and leave the striker free to hit the primer—the danger of premature explosion is almost negligible. We shouldn't have time to revolve the safety blades enough, and I'm pretty certain that even a heavy blow on the war-head itself would not explode the charge."

"Then I'm done," said Vernon dejectedly. "Think of something, old man—something that will hold water."

Silence ensued for nearly ten minutes, broken only by the tapping of the waves against the sides of the submarine, and the gentle purr of the dynamos for supplying light to the interior of the vessel.

Suddenly Ross leapt out of his bunk. He dared not trust himself to speak above a whisper for fear of being overheard.

"Dash it all, old man!" exclaimed Vernon, when his chum had confided his plans; "it ought to work. If it doesn't, nothing else will. I'm on it, happen what may!"

"We'll want our knives for the job," continued Ross. "Yours will open easily, I hope? Good! Sharp? We'll run no risks. A sharp blade is absolutely necessary."

They drew the knives and whetted the blades upon the soles of their boots. At Vernon's suggestion they kept open the big blades, making a hole through the lining of their pockets in order to keep the knives in a horizontal position and ready to hand.

"Now let's turn in properly," suggested the practical Ross. "We want to be fairly fresh for the job in front of us."

Soon after sunrise on the morrow all hands were mustered aft on deck, Ross and Vernon included. It was a bright morning. The sun had risen seemingly out of the sea, or in nautical parlance it was a "low dawn". There was a chilliness in the air that made the lads wish that they had been wearing overcoats.

They looked in vain for U75's consort. The unterseeboot that was to deal the coward's blow was not to be seen. Her presence was to be kept a secret from the crew of the decoy.

Kapitan Schwalbe, accompanied by his Unter-leutnant, made his way aft. He looked pale and care-worn. He had lost his military manner. His gait suggested that of a man recovering from a long illness.

"My men," he exclaimed, "circumstances over which I have no control make it necessary to bring our cruise to a speedy termination. U75 is no longer in a state of efficiency, either for offence or flight. It therefore remains for us to save our lives by surrendering to the first English ship of war that we fall in with. It is a humiliating and distasteful step to take, but there is no option."

The crew heard this lying speech in silence. They hardly knew what to make of it. The majority mentally decided that it was better to be imprisoned in England than to rot on the bed of the sea. Kapitan Schwalbe had no faith in his men's histrionic abilities; he was also afraid that they would oppose the scheme that he himself had deprecated as being too risky.

Hiding their indignation, Ross and his chum saw the Kapitan hand a petty officer a white flag. The man took it, and lashed short pieces of cord to two adjacent corners.

Hans Koppe sidled up to his charges.

"You will soon be free," he remarked. "Ach! but you do not seem overjoyed. You English are indeed a queer race."

Receiving no reply, the man went below to follow the example of his comrades, who were getting together their personal belongings. Many of them thought of the times when they had seen non-belligerents do likewise. It was the boot on the other foot with a vengeance.

Ross gave another glance across the horizon. Nothing was in sight. Gripping his chum's arm, he led him for'ard. U75 was motionless. The deck was deserted. A quartermaster stood on the navigation platform in front of the conning-tower. Kapitan Schwalbe and his Unter-leutnant had likewise vanished.

As Ross passed the conning-tower, he pulled out his knife and deftly severed the lashings of a couple of buoys secured to the hand-rail. It was the first act of the lad's plan of operations.

"Vessel on the port bow, sir!" shouted the quartermaster.

Kapitan Schwalbe was on deck in a trice, closely followed by his subordinate. For a few moments, he kept his binoculars focused upon the indistinct grey object, then three miles off.

"It is the Tremendous," he announced in an undertone to the Unter-leutnant. "Another ten minutes will see the business through."

He spoke with confidence, but it was a confidence inspired by a liberal dose of brandy. He felt that he had already passed the Rubicon. There could be no turning back.

A whistle trilled shrilly. At the signal the men again doubled aft, and joined up in a double line.

"Where are the English boys?" enquired Kapitan Schwalbe.

"Coming," replied Ross. For the first time on board he omitted to add the word "sir". His omission was deliberate. Utter contempt for the German captain consumed him. Schwalbe, too, noticed the manner in which he had replied. He smiled grimly, imagining that now the lads thought themselves about to be free they could afford to be curt.

As the chums passed the lifebuoys, they deftly heaved them overboard. They fell with hardly a splash, dropping close to the side of the motionless submarine.

No one noticed the act. The attention of the crew was centred upon a little ceremony that was taking place. Bareheaded, the men stood at attention. Their voices broke into the song of "Die Wacht am Rhein" as the emblem of German sea-power was slowly lowered from the ensign staff.

The men sang sonorously and in perfect cadence. They firmly believed that it was their last tribute as free men to their Fatherland. As the last bar terminated, the petty officer smartly hoisted the white flag. For an instant it hung limply, confined by one of the halliards; then like a square of stretched canvas it blew out in the steady breeze—a modern counterpart of the kiss of Judas.

And standing just behind the Kapitan, within arm's reach of the ensign staff, were Ross Trefusis and Vernon Haye.

CHAPTER XII

The White Flag—and Afterwards

H.M.S. Tremendous, super-Dreadnought of 24,000 tons displacement, and mounting ten 13.5-inch guns as her principal armament, was tearing up-Channel at 21 knots.

She looked far different from the spick-and-span battleship which had left Portsmouth only six weeks previously.

Her armoured sides still showed unmistakable traces of the impact of Turkish shells. Her grey paint was blotched, blistered, and stained. Her after funnel had plates of sheet-iron riveted to it to hide a gaping hole large enough to drive a stage-coach through. Her guns were worn out by sheer hard work. It was mainly on this account that she was homeward bound: to have the gigantic weapons "re-lined" in order that she might again take her place as an effective unit of the Grand Fleet.

The middle watch was about to relieve the morning watch. The mess decks were a seething mass of humanity. In spite of the apparent confusion everyone was in high good humour, for another few hours (D.V.) would find H.M.S. Tremendous at Pompey—as Portsmouth has from time immemorial been termed by the Navy.

On the fire-control platform sleepy-eyed officers were awaiting their reliefs. Around the 12-pounders, the muzzles of which grinned menacingly from apparently haphazard positions in the superstructure, men were grouped, ready at the first alarm to train the weapons upon a possible foe. Day after day ceaseless vigilance was maintained. One and all realized that a moment's negligence might result in destruction by one of the most horrible creations of modern science.

"Submarine on the starboard bow, sir!"

For an instant all was tense silence. Then a bugle blared, followed by the clear trills of the bos'n's mates' pipes and the hurried tramp of men's feet.

The officer of the watch brought his telescope to bear ahead. He was a junior lieutenant, Bourne by name, and in receipt of a private income of eight hundred a year. On that sum he might have lived the life of a man of leisure, but he vastly preferred a strenuous life as a commissioned officer in the Royal Navy. Not once had he regretted his choice, and upon the outbreak of war he was ready to execute a hornpipe of sheer delight at the prospect of "being in the big scrap".

"She's flying the white flag, by Jove!" he ejaculated. "Funny, deucedly funny!"

He had to act, and act promptly, for a battleship travelling at 21 knots does not give a man time to think for any length of time. Already a messenger had been despatched to inform the "skipper", but before the captain could gain the navigation bridge (more than likely he was in his bath) the Tremendous would have covered the intervening distance.

The quartermaster looked enquiringly at the Lieutenant. Bourne stepped hastily to the engine-room telegraph indicator, half inclined to ring down for "half-speed", or even "stop both engines".

He stopped abruptly.

"Steady on your helm, quartermaster."

"Steady it is, sir," replied the petty officer.

The telegraph indicator remained untouched. With undiminished speed H.M.S. Tremendous held on, under the propelling force of turbine engines of 30,000 indicated horse-power.

A midshipman, standing by the side of the officer of the watch, had been keeping the submarine under observation by means of his telescope.

"By Jove, sir!" he exclaimed. "There's something wrong there. The white flag's down, and two fellows in mufti have leapt overboard."

"Torpedo on the port bow, sir!" sang out half a dozen lusty voices in chorus.

"Hard-a-port, quartermaster!" ordered Bourne.

The spokes of the steam steering-gear revolved quicker than they had ever done before. Listing heavily to port, the Tremendous turned with a rapidity that belied her huge bulk and apparent unhandiness. A double track of ever-diverging foam marked the progress of the deadly missile. Another followed almost in its wake, both torpedoes travelling at the speed of an express train.

For four seconds all on board who watched these messages of death stood with bated breath. Then a general roar of relief went up as the two "tinfish" glided harmlessly past the ship, the nearest at a distance of less than twenty feet, and parallel to the new course of the battleship.

Half a dozen quick-firers spat viciously. A 6-inch, two of which for some obscure reason the designers had placed on the main deck abreast of the after 15-inch guns, added to the din. A chaos of smoke, flame, and spray marked the spot beneath which U77 had lurked to launch her cowardly and treacherous bolt.

"That's blinded her, at least," thought Bourne.

He knew that even if the hidden submarine had escaped injury, a minute at least would elapse before she could be conned into a position to discharge another torpedo. That minute would be enough for his purpose.

"Starboard!" he ordered. "Ram her, quartermaster!"

Round swung the 24,000 tons of dead weight, steadied, and bore down upon the motionless U75. Cries of terror burst from the doomed crew, many of whom leapt overboard in a vain attempt to swim clear of the vengeful leviathan.

Bourne gripped the guard-rail, half expecting to be thrown violently by the force of the impact. He was mistaken.

With hardly a tremor the bows of the Tremendous crashed into the unterseeboot, hitting her just abaft the conning-tower. The bow portion sank like a stone. The after part reared itself high in the air, revealing the curiously shaped stern, the two propellers, and the complication of rudders. Then, before the cloud of smoke and spray had time to drift inboard, the Tremendous was over and beyond the ever-widening circle of iridescent oil that marked the ocean grave of yet another of the would-be blockaders of Britain's shores.

Even in the midst of his great responsibility Bourne's keen eye discerned two heads bobbing up and down in the water. The midshipman noticed them too.

"They are those fellows who hauled down the white flag, sir," he exclaimed. "They are quite youngsters, too, and we daren't stop."

"No, we dare not," agreed the Lieutenant. For aught he knew, another unterseeboot might be in the vicinity, reserving her torpedoes in the hope that the battleship would slow down to investigate. "Pass the word to the sentry to let go the Kisbie. It's the best we can do."

With a splash the patent lifebuoy was dropped from the cage at the extremity of the navigation-bridge. It bobbed up again under the battleship's quarter, emitting a dense cloud of calcium smoke as it did so. By the time the marine had dropped the Kisbie the ship was a quarter of a mile away from the two swimmers.

"It's the best we can do," repeated Bourne as he closed the eyepiece of his telescope. "They may fetch it, they are swimming strongly."

"Well done, Mr. Bourne!" exclaimed a deep voice.

Turning, the Lieutenant faced the Captain standing beside him.

"A smart manoeuvre!" continued the skipper approvingly. "We can now only carry on; but we'll wireless the Commander-in-Chief Devonport, and report that there are survivors from the rammed submarine. He'll have a destroyer patrol on the spot within an hour, and I hope it won't be too late."

Bourne stepped to the extremity of the bridge and glanced astern. His effort to distinguish the heads of the two swimmers was fruitless, for a thin haze, the smoke from the ship's funnel, spread far in her wake, completely obliterating the spot where Ross Trefusis and Vernon Haye were swimming for dear life.

It will be necessary to set back the hands of the clock in order to follow the fortunes of Ross and his chum.

"Is she slowing down?" whispered Vernon anxiously, as they stood on the deck of U75 awaiting the approach of the Tremendous.

"I don't think so," replied Ross. "But now's our time."

The attention of Schwalbe and his crew was centred upon the battleship; the Kapitan momentarily expecting to see the huge vessel reel under the impact of the terrible torpedo, while the men began to entertain grave doubts as to whether the British ship would accept their token of surrender. The fact that the super-Dreadnought showed no signs of slowing down revived Kapitan Schwalbe's doubts. Knowing the difficulty of hitting, even at a comparatively short range, a swiftly moving target, he began to wonder whether he did the right thing in falling in with von Hoffner's diabolical plan.

His hurried thoughts were suddenly interrupted by some light object enveloping his head and shoulders. Before he could tear the fabric away he heard two distinct splashes, followed by shouts of astonishment from the crew; for with one clean sweep with his knife Ross had severed the halliards of the ensign staff.

The lads dived deep, swimming the while with long, powerful strokes, for both were accomplished in the art of natation. They were longer in coming to the surface than they anticipated, owing to the weight of their half-boots, which they had been unable to remove without risk of causing suspicion.

When at length their heads emerged almost simultaneously, they found themselves nearly fifteen yards from the doomed U75.

"Strike out!" spluttered Ross. "Get as far away from her as you can. Never mind about old Schwalbe. He can't hurt us."

Ross was right, for however much the Kapitan wanted to wreak his vengeance upon his former prisoners, he was unable to do so. In his rôle as that of an officer waiting to surrender, the possession of a revolver would tend to "give the show away". He had left his pistol in his cabin—an example that his Unter-leutnant had followed. And now his attention was directed upon the British battleship.

Meanwhile, the lads, swimming strongly, saw the Tremendous heel as she ported helm. For a minute, not knowing how a ship behaves when the helm is suddenly put hard over, they thought that the treacherous unterseeboot had successfully carried out her cold-blooded plan. Yet no explosion occurred, and the battleship recovered her normal trim.

With their eyes only a few inches above the surface, the lads could see nothing of the track of the torpedoes. They had no indication that they had been fired until the Tremendous let fly with her 12-pounders.

"I think we've saved her," said Vernon. "Now there'll be trouble for us. Schwalbe will certainly have a shot at recapturing us after the battleship has cleared off. Why doesn't she settle U75, I wonder?"

The lads both expressed astonishment that the motionless unterseeboot had escaped the attention of the super-Dreadnought's quick-firers. It seemed as if the latter were ignoring U75 altogether and was sheering off at full speed.

Suddenly Ross gave a whoop of delight, which ended in his swallowing a mouthful of salt water. The Tremendous was turning once more, and heading straight for the doomed submarine.

"THE TREMENDOUS WAS HEADING STRAIGHT FOR THE DOOMED SUBMARINE"

Mentally Ross compared the on-coming battleship with an express train, as shown on a cinematograph screen, in the act of approaching the audience. At one moment the ship was visible from her water-line to the truck of her top-mast; at the next her bulk had suddenly expanded and seemed to fill the complete field of vision. It looked as if the two lads, in spite of the distance they had put between themselves and the motionless submarine, would yet be in the way of the vengeful battleship, whose extreme beam was not less than ninety feet.

Yet neither of the two chums made the slightest effort to swim farther away. Mechanically treading water, they waited and watched.

They could see the terror-stricken attitudes of the crew of the doomed U75. They heard the shouts of consternation as the massive steel bows bore down upon her. Then, in a second it seemed, there was a hideous crash that outvoiced the yells and shouts of despair as the unterseeboot was rent in twain.

Of what happened during the next minute the lads had but a very hazy idea. Caught by the irresistible bow wave as the Tremendous tore past, they were hurled aside like feathers and buried a couple of fathoms down under the breaking, foaming mass of water. Vaguely they heard the whirring of the four propellers—very near, it seemed; then, caught by an eddy caused by the cavitation in the wake of the monstrous vessel, they were separated and flung to the surface, half-breathless and dazed.

Ross opened his eyes. The Tremendous had already covered nearly a quarter of a mile. Twenty yards away he saw his chum's head, as Vernon, puffing like a grampus, was striking out towards him.

Where the submarine had dived for the last time was an ever-widening circle of oil. Those of the German crew who had not been carried down by the sinking unterseeboot were too shaken by the concussion to make any great effort to save their lives. Attempting to keep afloat in that oil-covered water added to their difficulties, for whenever the head of a swimmer disappeared he did not rise again.

"Kick off your boots, old man," exclaimed Ross.

"Where are the lifebuoys?" asked Vernon as he carried out his friend's advice.

One buoy had disappeared; the other was supporting a seaman, the only survivor of the crew.

"A case of finding's are keeping's," announced Ross. "We can't sling him out of it. It might support two people. We could take turns at hanging on."

"Stop!" exclaimed Vernon as Ross began to strike out towards the buoy. "There'll be trouble if we get mixed up in that oil. It's much lighter than water. I doubt whether we could swim in it. Do you think the Tremendous will put back?"

"Not likely," replied Trefusis.

He looked in the direction of the fast-vanishing battleship, half hoping that she would slow down and lower a boat. As he did so, something caught his eye: a cloud of grey smoke apparently issuing from the sea.

"What's that?" he asked, pointing in that direction.

"Torpedo, perhaps; one that has finished her run," suggested Vernon; but his chum waved aside the explanation.

"If U77 did fire a torpedo, you can bet your bottom dollar it wasn't one with a dummy head!" he said. "Only practice torpedoes send up a calcium light when their compressed air has given out. By Jove, I believe it's one of those patent buoys! Let's make for it."

The lads swam strongly, making powerful and comparatively slow breast-strokes. The water was warm. They were in no immediate danger of cramp.

As they skirted the patch of oil they noticed that the seaman holding on to the buoy had turned round. His face was now in their direction. The man was Hans Koppe.

"Are you all right, Hans?" shouted Ross.

"Yes, mein herr," replied the man. "I've found a buoy."

"Thanks to us," thought Trefusis; then raising his voice: "You had better kick out and get clear of the oil," he advised. "We are making for yonder buoy."

By the time the swimmers reached the Kisbie the emission of calcium smoke had ceased. They found that not only did the buoy support them both, but that it was so constructed as to allow them to maintain a sitting position without having to hold on with both hands. Glad of a seat they waited, watching the approach of Hans Koppe, and also looking for the undesired reappearance of U77.

"Ach! My wife and children!" exclaimed Hans Koppe disconsolately, as he brought his lifebuoy close alongside. "I shall never see them again."

"Cheer up, Hans!" replied Vernon. "At any moment U77 might come to the surface and take you on board. We don't mind, so long as they let us alone. We've had enough of your unterseebooten."

"U77?" gasped the German incredulously. "How do you know that?"

Briefly Haye related the story of the ill-fated Kapitan Schwalbe's treachery. As he proceeded Han's face bore a surprised expression that presently changed to one of fear.

"If we are picked up by an English ship," he remarked, "they will shoot me for abuse of the white flag. And I am innocent. Ach! my poor wife."

"They won't," replied Ross reassuringly. "We can swear that you knew nothing about it."

The minutes passed slowly. There was no sign of U77. Little did the three survivors know that she lay within a quarter of a mile of her consort, on the bed of the English Channel—to add to the ever-increasing roll of unterseebooten that were fated never to enter a German port again.

The sun rose higher and higher, its rays gathering strength as it did so. The heads of the three survivors were exposed to the solar heat; their bodies and limbs were numbed by prolonged immersion. The desire for conversation had long since passed. Almost exhausted they hung to their supports, listless and torpid. A few sea-gulls, struck with the silence of the three men, hovered overhead, and swooped with shrill cries to settle on the water within close distance of what appeared to be a possible meal. One bolder than the rest perched upon Trefusis' head.

Raising his arm, Ross dealt the bird a furious blow. It missed, but had the effect of scattering the gulls. Apathetically the lad watched them as they flew off. As he did so he caught sight of three vessels being driven at high speed.

"Hurrah!" he exclaimed feebly. "The destroyers, old man; we are saved!"

CHAPTER XIII

The Arm of the Law

"Hulloa! What the deuce have we got here?" enquired Commander Devereux of H.M. torpedo-boat destroyer Yealm, as three dripping figures were transferred from the destroyer's dinghy to the deck. "One strafed Hun, right enough; but who are these fellows in mufti?"

"Can't say, sir," replied the coxswain. "They sort o' collapsed directly we got 'em into the boat."

"Then take them below," continued Devereux. "I say, Fanshawe, there's a job for you at last, my festive sawbones."

Fanshawe, lately a young country practitioner with a scattered "panel" connection, had but recently entered the Navy as a surgical probationer R.N.V.R. He joined purely through patriotic motives, having sacrificed a fairly substantial income in order to do so. Up to the present his work had been almost a sinecure. The Yealm had not had the faintest chance of taking part in an engagement. Her crew—to use Fanshawe's own words—were "that beastly healthy, don't you know", that, out of sheer anxiety to do something, he was learning navigation from the Sub-lieutenant.

The medico undertook his first important professional task on board the Yealm with great alacrity, and it was not long before Ross and Vernon were in a fit state to be questioned. Hans Koppe was in a bad plight. So utterly shaken were his nerves that he seemed on the point of collapse.

"So you are the son of Admiral Trefusis," said the Lieutenant-Commander. "I can't say that I know him personally, although I know of him. But how did you get on board the submarine?"

Ross explained. He felt hurt at having to do so. The Lieutenant-Commander's ignorance of the disappearance of the two chums from St. Mena's Island "took all the wind out of his sails". In pre-War days the principal papers would have devoted at least half a column to the supposed deaths by drowning, off the Cornish coast, of two well-connected youths. Nowadays editors had neither space nor inclination to devote to such a comparatively trivial matter. Consequently Devereux could be exonerated of all lack of knowledge of the supposed accident. Yet his interest grew as Ross proceeded with his narrative.

"Look here," he remarked. "We've got to dodge around for a few hours in case your pal U77 does put in an appearance. But I'll wireless the Admiral and ask for a telegram to be sent to your homes, to let your people know you are still alive and kicking."

"Better not, sir," objected Ross.

Devereux looked curiously at the lad.

"And why not?" he asked.

"Well, you see," explained Trefusis, "a telegram is not such a confidential matter as one would like it to be, especially in a remote country district."

"It's good news though," remarked the Lieutenant-Commander.

"Yes," admitted Ross; "but it is absolutely necessary to keep it dark for a while. A few hours won't make very much difference one way or the other to my people, but it would make a thumping lot to our friend Dr. Ramblethorne, otherwise von Hauptwald. If he were to hear that we were alive, he'd do a bunk. The same with that other spy, von Ruhle. They must be arrested promptly, and within a few hours of each other, in case one of them scents trouble and clears out."

"I see your point," admitted Devereux. "I won't send a wireless at present. You must be feeling peckish. I'll get my steward to bring you in some grub. Excuse me, I must be off again. We've a lot to attend to, you know."

The Lieutenant-Commander went on deck to conduct operations. He was temporarily senior officer, and it fell to him to issue orders to his two consorts relating to the investigation of the scene of the battleship's exploit.

For two hours the three destroyers cruised over the spot where the two submarines were supposed to have sunk. At length wreckage was found by means of grapnels. It was, of course, much too deep to send a diver down to report; but the spot was buoyed, and served as a base while sweeping operations were proceeded with in the hope of locating the hull of the second unterseeboot. In a very short space of time two operations undertaken for the purpose of destroying the sunken submarine were highly satisfactorily carried out. The first resulted in the release of a small quantity of buoyant wreckage, amongst which was the flagstaff of U75. The second brought to the surface a quantity of oil, showing that a submarine had been sunk there, but the injuries she previously received had not been sufficient to liberate the contents of the heavy oil-tanks. The explosive charge had completed the destruction of U77.

Just before five in the afternoon, the Yealm and her consorts passed the eastern arm of the breakwater in Plymouth Sound and brought up in the Hamoaze. Ross and Vernon, arrayed in borrowed clothes and accompanied by Lieutenant-Commander Devereux, lost no time in going ashore and proceeding to the offices of the Commander-in-Chief.

"You are acting with remarkable discretion," observed the Admiral, when Ross reiterated his desire not to communicate with his home until the spies were safely under lock and key. "Fortunately there ought to be no undue delay, as we have two expert Scotland Yard men investigating a case in the Dockyard. I'll telephone to the Superintendent of Police, and get him to send the officers here at once."

Within ten minutes the officers were ushered into the Commander-in-Chief's presence. Ross and Vernon looked at them with considerable curiosity. It had not before fallen to their lot to come into contact with two real representatives of the famous Scotland Yard. Yet there was little about the appearance to occasion comment. They were not in any way disguised. The taller of the two, who was introduced as Detective-Inspector Ferret, was about forty years of age. His closely cut hair was dark-brown, with a plentiful sprinkling of grey hairs. He wore a beard trimmed naval or "torpedo" fashion, with a moustache. He was dressed in a grey lounge suit, with dark-brown boots and a golfing cap. There was nothing of a piercing nature about his eyes, which were of a deep-grey tint. He seemed to be perpetually beaming; the lines on his face gave one that impression.

His companion, Detective Hawke, was a short, thick-set man of about thirty-five. He was clean-shaven. His features were ruddy and heavy. There was a bulldog look about his jaw that proclaimed him to be a tough customer. His rough, brown, Harris-tweed suit and bowler hat gave him the appearance of a prosperous yeoman rather than a successful tracker of criminals.

"Now, young gentlemen," began Mr. Hawke briskly, after the introductions had been made, "we'll get to business. With your permission, sir" (addressing the Admiral), "I will ask Mr. Trefusis to give me his version of the affair. To save time, I feel certain that Mr. Haye will have no objection to going with my colleague and telling him his story. That, I must explain, is the best way to eliminate any discrepancies. We prefer to make a fair start, and then all ought to go well."

During the next hour Detective-inspector Hawke was very busy. He made no written notes. He relied solely upon his marvellous retentive memory, and it was not long before he was in full possession of the facts of the case.

His next step was to telephone to St. Bedal. From the police there, he learnt that Dr. Ramblethorne was medical officer to the 4th battalion of a west-country regiment, but that he was temporarily detailed to act on the recruiting staff at Wellington.

Hawke thereupon telegraphed to Harwich. The Customs officers there informed him that the Harwich-Flushing boat service had been suspended for nearly a week, owing to the discovery of a hostile mine-field off the Dutch coast. Sailings were to be resumed that night. A man who gave himself out to be a Dutchman, but who answered to the description of von Ruhle, had applied that morning for a permit to leave the country by the night boat. His berth had been booked under the name of Cornelius Vanderhuit.

"Which one ought we to nab first?" asked Ferret. "We'll have to be very sharp, or one of them, finding that he is no longer in communication with his accomplice, would smell a rat and clear out."

"Under normal conditions I would reply, 'Collar the principal first'," replied Hawke. "It is evident that Ramblethorne, alias von Hauptwald, is the master-spy. Directly he's laid by the heels, the whole of the organization immediately under his control goes by the board. But there's this Harwich business. Von Ruhle crosses the North Sea to-night, unless otherwise prevented. We comprise the otherwise, I hope."

"Then it would mean catching the midday express to Waterloo," remarked Ferret.

"Could we go with you?" asked Ross.

The police officers looked rather astonished at the cool request. Like most professional men, they scouted the idea of amateur assistance when the main issue was at stake.

"Perhaps it wouldn't be a bad idea," remarked Hawke. "You have already shown great discretion in the matter. Most fellows would have made a bee-line to the nearest telegraph office and given the whole show away. The only difficulty is—I suppose, by the way, you are not feeling too done up after your trying experiences?—the only difficulty is, I was remarking, that von Ruhle might spot you. Look here, Ferret; suppose you take these young gentlemen, and proceed to Harwich by an ordinary train? Keep well out of sight when you arrive at Parkeston Quay, but keep a sharp eye on the boat. I'll travel from Liverpool Street by the boat train, and see if I can pick out our quarry amongst the passengers."

It was a tedious journey from Plymouth to Harwich. Arriving at Waterloo, Ferret took the lads to a quiet hotel and ordered lunch; while Hawke, excusing himself, called in at "the Yard" to report his new case to the Chief, and to wait for the Great Eastern boat train.

The weather had changed completely during the run from the West, for when Ferret and the two lads arrived at Parkeston Quay it was raining heavily, accompanied by half a gale of wind from the east'ard.

"We've a long wait," commented Ferret. "Fortunately I know several of the Customs officials very well. I'll get them to let you take shelter in their shed. It's almost opposite the berth where the steamer generally makes fast. You'll be able to watch everyone who goes up the gangway. I'll go on board and speak to the steward. I don't suppose we'll spot friend von Ruhle until the boat train arrives, and by that time perhaps Hawke will have marked his man."

Undoubtedly, the wisest course would have been to send other officers to Wellington to arrest Dr. Ramblethorne; but Hawke was out for "kudos". Only a short while ago he had let a wanted man slip through his fingers, and had been rapped over the knuckles for it. With the professional assistance of Ferret, he hoped to carry out a double coup and arrest both German Secret Service agents, thereby recovering his lost prestige.

Arriving at Liverpool Street he took his ticket, and spent the time until the departure of the boat train in walking up and down the platform. He had the knack of observing without being observed. He would look at a man in quite a casual way; there was no gleam of intelligence in his eyes as he did so, but little escaped his notice. An hour or two later he could accurately describe his appearance, dress, and mannerisms.

A minute before the train started, a man answering von Ruhle's description hurried down the platform. He carried a new cane under his left arm. In his right hand he held an attaché case with the initials C. V.

Hawke waited until he had entered a carriage, then strolled to the other end of the corridor coaches and took his seat. He knew that the run was supposed to be a non-stop one.

The train started. The detective took his time. He waited for nearly twenty minutes before he made his way along the corridor, and entered the smoking-compartment occupied by the suspect.

Presently Hawke made a commonplace remark. The stranger replied stiffly and in rather a deep voice, with a slight foreign accent.

"An assumed voice," soliloquized the detective; but undaunted by the chilliness of his reception he again made some remark about the weather.

Before the train ran through Witham station, conversation was proceeding briskly. Hawke assumed the rôle of a commercial traveller, and volunteered the information that his brother had just returned from the Front.

The stranger showed no hesitation in discussing the war. Emboldened, the detective tackled the subject of East Coast defences and the futile German blockade.

"He's giving me absolutely false information," he thought. "Perhaps he's trying to throw me off the scent. I'll put a few questions that no one but an ignoramus would ask in good faith. If he's trying to bluff me, I'll beat him at that game."

Presently his fellow-passenger excused himself and, without removing his luggage, went into the corridor. As soon as he was out of sight Hawke took hold of the cane that the stranger had left in the rack. With a grunt of satisfaction he found that it was certainly not a Malacca, but made of metal.

The train began to slow down. Lifting the blind, Hawke looked out of the window. He could just discern a fairly big town, completely in darkness.

"Manningtree Junction," said Hawke to himself. "Something on the line, I suppose. H'm, we're stopping."

With a jerk the train pulled up at the station. The platform was almost deserted, for no train was due at that time to stop there. A door slammed. Again the detective pulled aside the blind. He was just in time to see his fellow-traveller, accompanied by the guard, disappear into the station waiting-room.

"He's tumbled to it!" exclaimed Hawke. "He's making off. He's tipped the guard to set him down. I'm after him!"

He made his way swiftly and stealthily down the platform, and with a quick movement threw open the waiting-room door.

The sudden transition from the semi-darkness of the platform to the brilliantly lighted interior of the room temporarily dazzled his eyes. Dimly he was aware that the place was occupied by khaki-clad soldiers struggling into their equipment, and that in their midst was the guard and the man of whom he was in search.

"At any rate there is plenty of assistance," thought Hawke as he advanced to tap the suspect on the shoulder; but before he could attain his object a deep, stern voice exclaimed:

"Arrest him, men!"

The next instant Detective-inspector Hawke was seized by half a dozen muscular hands.

"What's this tomfoolery?" he demanded angrily. "I'm a Scotland Yard officer, and——"

A roar of laughter burst from the Tommies. Even the subaltern in command smiled broadly.

The stranger spoke again.

"Take him to the guard-room. He is arrested under the Defence of the Realm Act for attempting to elicit information prejudicial to the welfare of the State. I won't detain the train any longer, guard, although I'll ask you to drop my gear on the platform."

Still protesting vehemently but ineffectually, the detective was unceremoniously hustled into an ante-room, used since the outbreak of the war as a guard-room for the military in charge of the line. The door was locked upon him. He heard the train rumble out of the station.

CHAPTER XIV

A Fruitless Quest

From their places of concealment Ross and Vernon watched the boat train run alongside the steamer. At last the weary vigil was a thing of the past. All fatigue was forgotten at the prospect of witnessing the capture of one of the active members of the German spy system at work in this country.

For a quarter of an hour everything was in a state of bustle. There was a continuous stream of passengers and porters, the latter bending under the weight of trunks and boxes as they hurried up the steeply sloping gangway.

At length the throng thinned. As yet there was no sign either of von Ruhle or of Detective-inspector Hawke.

A man with his coat collar turned up ran through the driving rain and entered the shed. It was Ferret.

"Something's gone wrong," he declared. "I've just had a telephone message from my colleague. I'm off to the post-office. If you want me during the next ten minutes you'll find me there."

Hawke had at length managed to get a word with his former fellow-traveller, who happened to be a staff-officer of the Eastern command. The detective had been under a misapprehension. The officer had good reason for ordering his arrest; but the comedy threatened to take a serious development. Even when the detective showed his credentials the officer was not satisfied. He proposed telegraphing to Scotland Yard, but Hawke, mindful of a former failure, induced him not to do so. The detective, who had occasion to contrast unfavourably the summary powers of arrest under the Defence of the Realm Act with those allowed by the Civil Power, was eventually allowed to communicate with his brother officer at Parkeston Quay. And then the military authorities required a considerable amount of convincing. It looked as if Detective-inspector Hawke would have to remain under arrest until next morning.

While Ferret was losing time and patience in his efforts to release his confrère, Ross and Vernon noticed a man hurrying along the quay. He was short and thick-set. He wore a long mackintosh, the collar of which was turned up and helped, with the peak of his cap, to hide his features.

Suddenly the man's foot tripped over a ring-bolt. He cursed under his breath, but sufficiently loudly for the lads to overhear.

Ross gripped his companion's arm. The fellow was swearing in German.

"Von Ruhle!" he whispered. He made a movement as if to issue from his place of concealment, but Haye restrained him.

"Hold on!" he cautioned in a low voice.

The man paused on the gangway. A partly shaded electric light threw a glare upon his face. He wore a heavy beard and moustache.

"You're wrong," whispered Vernon.

"He's a German, anyhow," persisted Trefusis.

The man still hesitated. Then he hailed a seaman.

"Where is the post office?" he asked. "I wish to telegraph. Is there time before the boat sails?"

Receiving an affirmative reply the man hurried off.

"Come on!" exclaimed Ross.

Neither of the lads had now any doubts as to the man's identity. The beard and moustache were false, but the voice was the same—von Ruhle's.

Keeping close to the wall of the line of sheds, the lads followed the spy at a distance of about fifty feet. More than once von Ruhle glanced furtively over his shoulder, as if suspecting that he was being tracked.

Presently a man, reeling along the quay, approached. The spy made no effort to avoid him. As the inebriated one rolled past he whispered a few words. The effect was instantaneous. Instead of continuing his way towards the post office, von Ruhle turned and made off abruptly in the direction of the gate of the Company's premises.

"An accomplice," whispered Vernon. "He's been warned."

They had to wait until the man who had feigned drunkenness had disappeared. By this time the German had gained a considerable distance. To get the assistance of the detective was out of the question.

"Come on!" exclaimed Ross, breaking into a run.

Concealment was no longer necessary. Should occasion arise, there would be plenty of help forthcoming, for there were several dock policemen and soldiers on duty close at hand.

Von Ruhle had increased his pace into a brisk walk when he heard the noise of his pursuers. Then he, too, began to run.

"Stop him!" shouted Trefusis, calling to a group of uniformed men standing in front of an abattoir.

Turning, the German made towards the quay-side. He was no match in speed for his youthful pursuers; but he gained the water's edge before Ross headed him off.

"Give in, von Ruhle!" he challenged.

The spy recognized the voice of the British lad whom he imagined to be miles away, on board an unterseeboot.

With a quick movement, the spy plucked a leather case from his coat pocket and hurled it over the edge of the quay, then, throwing up his arms, he dropped lifeless upon the rain-sodden ground.

Rapidly a crowd collected. Amongst them was Detective-inspector Ferret, who, having finished his conversation with his luckless confrère, was leaving the post office when he heard the commotion.

"Well, what's all this?" he asked brusquely. He bent over the body of the spy and flashed a pocket-lamp upon his face. "It's our man," he continued, addressing the lads in an undertone. This remark was needless, since they were already certain upon that point. "He's done us out of a job. Heart disease? No fear: it's poison. Don't wait here. Your work in this direction is done. I have still a few unpleasant tasks to perform. Cut off to the hotel and await me there. I may be an hour."

"One moment," protested Vernon. "We saw von Ruhle heave something over the quay. It might float; if so, there might be a chance to pick it up by means of a boat. The tide is almost slack. If it has sunk it will be a diver's task to recover it."

"'Something' is always unsatisfactory," remarked Ferret reprovingly. "Was it large, small, heavy, or light?"

"He was so jolly quick that I could hardly see it," replied Haye. "I should think it was about the size of a cigar-case."

Directing two policemen to remove and take charge of the body, the Detective-inspector accompanied the lads to the edge of the quay. It was dead low water. There was hardly sufficient current coming down the Stour to swing the anchored craft against the wind. Then the investigators made a discovery. Although there was a good depth of water at the greater extent of the quay, at this spot the mud was uncovered at the base of the wall, while almost at their feet was a flight of stone steps.

Ferret descended cautiously and switched on the light of the torch. Almost within arm's length, and partly buried in the slime, was the object which the spy had thrown away.

As the detective hooked at it with his stick a hoarse voice shouted:

"Ahoy there! What are you doing with that light?"

Apparently from nowhere a boat ploughed through the mud until its bows were within a couple of feet of the steps. The next instant Ferret and his companions were covered by a revolver.

It was a naval guard-boat, the watchful eye of the officer in charge having discovered what he took to be surreptitious signalling. Explanations followed, and were accepted. Ferret, holding the recovered prize, ascended the steps, followed by Ross and Vernon, while the boat backed noiselessly away. It was but one more example of the ceaseless vigilance of the great, silent Navy.

Almost dead-beat, Trefusis and his chum made their way to the hotel, had supper, and went straight to bed. Ferret, they decided, could wait until morning.

At 6 a.m. Hawke, having secured his release, arrived at Parkeston, having engaged a motor-car to bring him from Manningtree. Already his vindictiveness towards the military had vanished. He had taken a sensible view of the situation. He had played and lost, and the staff officer was justified in the circumstances. As for the soldiers, they had to obey orders.

Nevertheless he was chagrined when he heard his confrère's report. It was galling to think that their spy had outwitted him by taking his own life. The whole energies of the two detectives must, for the present, be concentrated upon the capture of the master-spy, Von Hauptwald, otherwise Dr. Ramblethorne.

Ross and Vernon met Hawke again at breakfast. He was now quite cheerful.

"You managed to get hold of von Ruhle so well," he remarked, "that I think you really ought to bear a hand with friend Ramblethorne,—that is, unless you've had enough of man-hunting?"

"We'll do our best," said Ross. "It's our duty."

"When do you start?" asked Vernon.

"Almost at once," he declared. "Ramblethorne might be alarmed if no telegram arrives from his fellow-spy. Again, the man who communicated with von Ruhle on the quay last night might have given Ramblethorne warning. It's not at all surprising to me, since what you told us, Mr. Trefusis, that there has been an alarming outbreak of enteric at St. Bedal camp."

He turned over several pages of a complex timetable.

"Here we are," he announced. "We must get to Paddington in time to catch the 10.20 for Wellington. One thing, young gentlemen, you'll be nearly home. Ferret has arranged about the inquest on von Ruhle. Your evidence will be taken down in writing, and in that case you won't have to put in an appearance at that grim farce."

Hawke spoke feelingly and from experience. In his opinion, based upon circumstantial evidence, "crowner's quests" were a form of legal absurdity.

The train journey to Liverpool Street was undertaken almost in silence, as far as the four travellers were concerned. Hawke buried himself in his paper; Ferret was poring over some document found in von Ruhle's pocket-book, trying to unravel the complex code that, if deciphered, would be of the utmost importance to the country. Ross and Vernon, still feeling tired, tried to make up for arrears of sleep.

Taking a taxi across London, they were just in time to catch the Great Western express, which would take them to Taunton. Arriving at that place, they changed into a slow train that eventually landed them at the little Somersetshire town nestling under the Black Down Hills.

Without delay the party proceeded to the regimental depot. Enquiries for Captain Ramblethorne, R.A.M.C., only resulted in looks of perplexity. He was unknown to the authorities.

"But we heard from St. Bedal that Captain Ramblethorne was ordered to Wellington for recruiting duties," persisted Hawke.

The orderly-room clerk smiled sadly.

"Are you quite sure that it was this Wellington?" he asked. "We've had similar mistakes before."

Detective-inspector Hawke felt like kicking himself. He, too, was aware of the existence of the Shropshire Wellington, but, without giving the possibility any consideration, he had rashly jumped to the conclusion that the place to which Ramblethorne had been appointed was the one nearest to St. Bedal.

Sorrowfully the four marched out of the office. More delay ensued while a wire was dispatched to St. Bedal, asking for further details.

It took two hours before the reply came. "Regret not to have added Salop to Captain Ramblethorne's address.—C.O."

"It's a long lane that has no turning," observed Ferret as they made for the railway station.

Hawke bit his lip. He knew that had the spy been warned promptly he might be out of the country by this time.

It was dark when, after a tedious journey, the four travellers alighted at Wellington, Salop. Here, guarded enquiries elicited the information that Captain Ramblethorne had gone to Bridgnorth to examine men "roped in" at a recruiting meeting. He had left for Bridgnorth two hours previously.

"There are no trains to-night," announced Hawke. "We'll have to get a car."

Ten minutes later, Ross and his companions were speeding over the horribly rough and hilly road between Wellington and Bridgnorth. Past ironworks and coal-fields, over or under a network of railway lines, the car tore; then, leaving the mining district behind, it entered the picturesque valley of the Severn, where the road skirts a range of towering limestone crags.

In spite of their fatigue, the lads could not restrain an exclamation of surprise and delight as the town of Bridgnorth, bathed in moonlight, appeared in sight—a cluster of houses perched upon a bold rock, and dominated by the scanty ruins of the old castle. At the foot of the cliff the Severn meandered placidly. In the midst of the greatest war the world has ever known, Bridgnorth appeared to retain all the characteristics of complete peace.

The recruiting office was closed for the night. With unerring instinct the detective made for the principal hotel. Here they found that Captain Ramblethorne had engaged a room, but the manager showed them a telegram that had just reached him.

"Took wrong train cancel room arriving to-morrow morning Ramblethorne."

"A blind," mentally ejaculated Ferret. "He has been warned."

The telegram had been dispatched from Shrewsbury. Ferret was again at fault, for the mistake was a genuine one. It so happened that the two trains left Wellington at precisely the same time, the one for Bridgnorth starting from a side platform. Before he realized his mistake Ramblethorne found himself well on the way to Shrewsbury, for the train stopped at no intermediate station.

"Shrewsbury, as hard as you can go!" ordered Hawke, addressing the chauffeur.

At a pace averaging fifty miles an hour the powerful car bounded over the road. Without mishap it gained the outskirts of the county town of Shropshire, when an involuntary halt occurred.

It was on the English Bridge, a comparatively narrow structure crossing the Severn. A belated drover was driving a herd of refractory cattle into the town when a motor-bicycle whizzed down the hill.

The cattle stampeded. With a jerk that almost threw Ferret and Vernon from the seat, the car brought up. At the same time the motor-bicycle slowed down, and dexterously avoiding a huge bullock, glided past the stationary car.

The moonbeams shone directly upon the rider's face as Ross thrust his head out of the window. The motor-cyclist was Ramblethorne the spy.

The recognition was mutual. The spy, cool and collected, gave no sign of recognition. The next moment he was travelling "all out" along the Much Wenlock road.

"That's Ramblethorne!" exclaimed Ross excitedly.

"Botheration take him!" ejaculated Ferret. "Are we to get no rest to-night?"

He opened the window in front of him. Hawke was sitting with the chauffeur. Quickly the detectives arrived at their decision.

"After that chap!" exclaimed Hawke, addressing the chauffeur; "that motor-cyclist who has just passed. Ten pounds if you overhaul and stop him."

It was the bright moonlight that had tempted Ramblethorne to go for a midnight ride. He was a keen out-of-door man. He could handle almost any make of car or motor-cycle with the utmost skill. Finding himself at Shrewsbury, he hired a motor-cycle from an agent, intending to have a run along the road following the banks of the Severn as far as Ironbridge. It was his practice, whenever in a strange place, speedily to become conversant with the locality. It was, in fact, part of his training as a spy.

Ramblethorne was somewhat taken aback when he saw Ross's face in the moonlight, although he betrayed no sign of surprise. In an instant he realized that, by some means, young Trefusis had escaped from U75; more, he was with a party of men evidently hard on his track.

Quickly he made up his mind. His career as a medical officer to the British Service was ended. He could no longer hope to serve the German Government in that direction. Before morning a hue and cry would be raised.

As he swung along the broad, level road he thought out his plans. He would ride as hard as he could until his supply of petrol gave out—a matter of about seventy or eighty miles. Then he would abandon and hide the motor-cycle, and make his way on foot to the Essex coast. There, he had means to get on board a nominally British fishing-boat, which would run him over to a Dutch port.

Although the motor-cycle was travelling at close on forty miles an hour, Ramblethorne glanced back over his shoulder. He hardly expected to be pursued. If the car had turned to attempt to overhaul him, it would almost to a certainty take the wider of the two fork roads—that leading to Wellington.

Disagreeably surprised, the spy saw the two powerful head-lights of the car less than a mile behind him.

The chauffeur of the pursuing vehicle had set his heart on winning the promised guerdon. "All out" the car bounded along the road, leaving in its trail a dense cloud of dust that slowly dispersed in the moon-lit air.

Hanging on desperately to the sides of the swaying car, Ferret and the two lads knelt upon the front seat of the coupe and peered through the dust-flecked glass at the solitary motor-cyclist in front. They were gaining—rapidly at first, but now the gap between lessened almost imperceptibly.

At that tremendous rate, the bursting of a tyre would result in complete disaster, yet not one thought did the pursuers give to the danger they were running. Their sole attention was centred upon the spy.

A sharp bend close to the village of Cressage enabled the car to get within fifty yards of the motor-cyclist. Hawke drew a revolver from his pocket. The chauffeur noticed the action out of the corner of his eye. Purposely he toyed with the sensitive steering-wheel, causing the car to swerve erratically.

"Put it up, sir!" he exclaimed, shouting in order to make himself heard above the roar of the wind over the screen. "If you bring him down we'll smash up on top of him before we can pull up. We'll have him on Harley Bank right enough."

A sharp run down through the village of Harley brought the car within sight of a very steep hill, up which the road wound like a silver thread against the black slope. This was Harley Bank, one of the steepest of many stiff Shropshire hills, its gradient averaging one in seven.

Up mounted the motor-cycle. Ramblethorne was attempting to take it on high gear.

The chauffeur of the car took no risks. He promptly dropped into second gear, with the result that the gap between them increased to nearly a hundred yards. Then the motor-cycle began to falter. Perhaps Ramblethorne was not thoroughly acquainted with the mechanism of the two-speed. By the time he got the friction-clutch into action the car had more than regained the lost distance—and the fugitive had not yet reached the stiffest part of the hill.

"Head him off—jam him up against that bank!" ordered Hawke.

"What for, sir?" asked the chauffeur. He had no objection to taking part in a midnight chase, but his sense of prudence told him that it was not advisable to deliberately smash up another vehicle.

"He's a spy," replied Hawke. "Don't hesitate. I will take all risks."

Fifteen seconds later the near front wheel of the car was abreast of Ramblethorne's back wheel. Hawke leant sideways with the intention of gripping the motor-cyclist by the collar, since the relative speeds were practically the same. At the same moment the car edged a little closer to the left-hand side of the road.

Ramblethorne realized the danger. A collision would with almost certainty result in his receiving a broken neck; capture meant ignominious death at the hands of a firing-party. There was yet a third alternative—a dash for safety.

He threw out the clutch and applied both brakes, at the same time bringing the motor-cycle on to the grassy bank. He alighted on all fours, but almost immediately regained his feet. The car was already twenty yards on ahead and still in gear.

He grasped his cycle by the handle-bars and raised it from its recumbent position. One look showed that the glancing impact had bent the front forks. The machine was no longer rideable. Without hesitation he sprang up the bank. As he did so he heard the footfalls of his pursuers.

"Be steady!" cautioned Ferret, as Ross and Vernon alighted from the car. "He may be armed. We're the people to take the brunt of it—not you."

They were now within a few feet of the summit of the road, which at this spot ran through the hill by means of a cutting. Close by were three excavations. Someone had evidently attempted to commence quarrying there, but had abandoned the undertaking. As far as the detective could conclude, these pits formed the only possible hiding-place in the vicinity.

"Hist!" exclaimed Hawke, holding up one hand to enjoin silence.

All was still. No sound of stealthily retreating footsteps reached their ears. Hawke knelt down and placed one ear to the ground.

"Someone breathing pretty hard," he whispered. "He can't be very far away; in one of these holes most likely. Perhaps he's hurt himself."

An investigation of the first possible hiding-place produced no result. At the second Ross heard a long-drawn sigh, emanating from a patch of bushes and tall grass.

"Here you are!" he exclaimed.

The place was in shadow, yet he could discern some dark object lying at full length in the midst of the grass.

In a trice the two detectives threw themselves upon their prey. For an instant the man struggled wildly. Ross and his chum joined in the fray, each hanging on desperately to his plunging legs. Ignominiously he was dragged from his place of concealment into the bright moonlight.

Ferret was the first to give a gasp of astonishment. Their victim was not Ramblethorne the spy, but a powerfully built tramp, who, finding himself released, began to expostulate with alarming vehemence.

"Stop that!" exclaimed Hawke authoritatively. "We are police officers. If you don't behave we'll take you in charge for sleeping out without visible means."

The fellow, cowed into silence, slunk away.

"Confound it!" ejaculated Ferret. "We've let Ramblethorne slip away under our very noses. He'll be clear by this time."

"I'm afraid so," agreed Hawke ruefully; then turning to the chauffeur he told him to drive into the nearest village, which happened to be Much Wenlock.

Here Ross and Vernon were able to secure a room at an inn, while the Scotland Yard men were busy at the little police station, getting a description of the spy issued through the countryside.

Next morning the lads set out on their return journey to Killigwent Hall.

CHAPTER XV

The Admiral Works the Oracle

"Look here, old man; what do you say about having a shot for the Naval Reserve?" asked Ross. "In ordinary circs I would be prepared to go through Sandhurst, but this isn't ordinary circs. Before we pass out, the war will be over perhaps."

"I'd rather like to see something of the fun," agreed Vernon.

"As if we hadn't already," added his chum. "But I know what you mean. Instead of being cooped up in an unterseeboot and hunted by our fellows, we want to have a hand in rounding up the German submarines. I vote we write to our respective governors about it."

This conversation occurred two days after the lads' return to Killigwent Hall. They had been given up as lost, and their unexpected return had caused unbounded rejoicings. Pressmen thronged the Hall to gather "exclusive" information of the manner of their seemingly miraculous rescue, but both Ross and Vernon were determined not to satisfy outside curiosity. They even kept the story of how the white flag fluttered down from the signalling mast of U75 from their immediate friends.

"It will take a long time for us to get a reply," objected Vernon. "By the time the letters hang about at the G.P.O., before they are sent to the fleet, a week will elapse, and before we get a reply bang goes a whole fortnight. Let's get hold of a Navy List and see what the qualifications are."

A careful perusal of the regulations resulted in a setback. Midshipmen in the R.N.R., they found, had to be between 16 and 18 years of age, and must either have passed through a course of instruction for two years on board an "approved" training ship, or else one year on board a first-class British merchant ship.

"That's put the hat on it," declared Ross.

"One minute," interposed Vernon. "Why not write to Admiral Garboard? He's an old shipmate of my governor's, and I know he's a bit of a pot up at Whitehall, although he's on the Retired List."

"He was with my pater in the old Rhodaphlare on the China station," added Ross. "We'll try; the wheeze might work."

Accordingly Vernon wrote to the Admiral, who lived about twenty miles from Killigwent Hall. Promptly came Sir Peter Garboard's reply:

"TRELANGKERRICK,"
CORNWALL.

"DEAR VERNON,

"In reply to your letter I am sorry that I cannot help you in the matter to which you refer, unless you and your friend can produce sufficient evidences of qualifications for the desired posts.

"On principle I object to influence in any shape or form. Entry into any branch of the Service should, like promotion, depend solely upon the aptitude and ability of a candidate. This has been my standpoint throughout the whole of my career, and I see no reason why I should now depart from it.

"If, however, you think you have strong reasons for pressing your claims, and you care to see me, we will go more fully into the matter.

"Believe me,
"Yours faithfully,
"PETER GARBOARD."

"Not so dusty," commented Ross. "He does leave us a loophole, although I'm afraid we'll have to blow our own trumpets. I vote we cycle over at once. We'll catch him in just before lunch."

"Better wait until after he's had his grub," said Vernon. "That's always the time to get a man in a good humour."

"We'll risk that," declared young Trefusis. "Come on."

It was a very hilly twenty miles run across the moors to Trelangkerrick. Starting at ten in the morning it took the lads two hours and a quarter, in the face of a strong south-westerly breeze, to cover the distance.

Half-way up the drive, they saw the Admiral and a companion emerging from a path leading from the kennels.