Thus to all outward appearance this performance was merely the torpedoing of a helpless merchant vessel. Yet the average German commander became altogether too wary to accept the situation in that light. He had no intention of approaching either lifeboats or the ship until entirely satisfied that he was not dealing with one of the decoy vessels which he so greatly feared. There was only one way of satisfying himself: that was to shell the ship so mercilessly that, in his opinion, if any human beings had remained aboard, they would have been killed or forced to surrender. The submarine therefore arose at a distance of two or three miles. Possibly the mystery ship, with one well-aimed shot, might hit the submarine at this distance, but the chances were altogether against her. To fire such a shot, of course, would immediately betray the fact that a gun crew still remained on board, and that the vessel was a mystery ship; and on this discovery the submarine would submerge, approach the vessel under water, and give her one or two more torpedoes. No, whatever the temptation, the crew must "play 'possum," and not by so much as a wink let the submarine know that there was any living thing on board. But this experience demanded heroism that almost approaches the sublime. The gun crews lay prone beside their guns, waiting the word of command to fire; the captain lay on the screened bridge, watching the whole proceeding through a peephole, with voice tubes near at hand with which he could constantly talk to his men. They maintained these positions sometimes for hours, never lifting a finger in defence, while the submarine, at a safe distance, showered hundreds of shells upon the ship. These horrible missiles would shriek above their heads; they would land on the decks, constantly wounding the men, sometimes killing whole gun crews—yet, although the ship might become a mass of blood and broken fragments of human bodies, the survivors would lie low, waiting, with infinite patience, until the critical moment arrived. This was the way they took to persuade the submarine that their ship was what it pretended to be, a tramp, that there was nothing alive on board, and that it could safely come near. The still cautious German, after an hour or so of this kind of execution, would submerge and approach within a few hundred yards. All that the watchful eye at the peephole could see, however, was the periscope; this would sail all around the vessel, sometimes at a distance of fifty or a hundred feet. Clearly the German was taking no chances; he was examining his victim inch by inch, looking for the slightest sign that the vessel was a decoy. All this time the captain and crew were lying taut, holding their breath, not moving a muscle, hardly winking an eyelid, the captain with his mouth at the voice pipe ready to give the order to let the false works drop the moment the submarine emerged, the gun crews ready to fire at a second's warning. But the cautious periscope, having completed the inspection of the ship, would start in the direction of the drifting lifeboats. This ugly eye would stick itself up almost in the faces of the anxious crew, evidently making a microscopical examination of the clothes, faces, and general personnel, to see if it could detect under their tramp steamer clothes any traces of naval officers and men.
Still the anxious question was, would the submarine emerge? Until it should do so the ship's crew was absolutely helpless. There was no use in shooting at the submerged boat, as shots do not penetrate the water but bounce off the surface as they do off solid ice. Everybody knew that the German under the water was debating that same question. To come up to the surface so near a mystery ship he knew meant instant death and the loss of his submarine; yet to go away under water meant that the sinking ship, if a merchantman, might float long enough to be salvaged, and it meant also that he would never be able to prove that he had accomplished anything with his valuable torpedo. Had he not shelled the derelict so completely that nothing could possibly survive? Had he not examined the thing minutely and discovered nothing amiss? It must be remembered that in 1917 a submarine went through this same procedure with every ship that did not sink very soon after being torpedoed, and that, in nearly every case, it discovered, after emerging, that it had been dealing with a real merchantman. Already this same submarine had wasted hours and immense stores of ammunition on vessels that were not mystery ships, but harmless tramps, and all these false alarms had made it impatient and careless. In most cases, therefore, the crew had only to bide its time. The captain knew that his hidden enemy would finally rise.
"Stand by!"
This command would come softly through the speaking tubes to the men at the guns. The captain on the bridge had noticed the preliminary disturbance on the water that preceded the emergence of the submarine. In a few seconds the whole boat would be floating on top, and the officers and crews would climb out on the deck, eager for booty. And this within a hundred yards of four or five guns!
"Let go!"
This command came at the top of the voice, for concealment was now no longer necessary. In a twinkling up went the battle flag, bulwarks fell down, lifeboats on decks collapsed, revealing guns, sides dropped from deckhouses, hen-coops, and other innocent-looking structures. The apparently sinking merchantman became a volcano of smoke and fire; scores of shells dropped upon the submarine, punching holes in her frail hull, hurling German sailors high into the air, sometimes decapitating them or blowing off their arms or legs. The whole horrible scene lasted only a few seconds before the helpless vessel would take its final plunge to the depths, leaving perhaps two or three survivors, a mass of oil and wood, and still more ghastly wreckage, to mark the spot where another German submarine had paid the penalty of its crimes.
IV
It was entirely characteristic of this strange war that the greatest exploit of any of the mystery ships was in one sense a failure—that is, it did not succeed in destroying the submarine which attacked it.
On an August day in 1917 the British "merchant steamer" Dunraven was zigzagging across the Bay of Biscay. Even to the expert eye she was a heavily laden cargo vessel bound for Gibraltar and the Mediterranean, probably carrying supplies to the severely pressed Allies in Italy and the East. On her stern a 2½-pounder gun, clearly visible to all observers, helped to emphasize this impression. Yet the apparently innocent Dunraven was a far more serious enemy to the submarine than appeared on the surface. The mere fact that the commander was not an experienced merchant salt, but Captain Gordon Campbell, of the Royal Navy, in itself would have made the Dunraven an object of terror to any lurking submarine, for Captain Campbell's name was a familiar one to the Germans by this time. Yet it would have taken a careful investigation to detect in the rough and unkempt figure of Captain Campbell any resemblance to an officer of the British navy, or to identify the untidy seamen as regularly enrolled British sailors. The armament of the Dunraven, could one have detected it, would have provided the greatest surprises. This vessel represented the final perfection of the mystery ship. Though seemingly a harmless tramp she carried a number of guns, also two torpedo tubes, and several depth charges; but even from her deck nothing was visible except the usual merchant gun aft. The stern of the Dunraven was a veritable arsenal. Besides the guns and depth charges, the magazine and shell-rooms were concealed there; on each side of the ship a masked torpedo tube held its missile ready for a chance shot at a submarine; and the forward deck contained other armament. Such was the Dunraven, ploughing her way along, quietly and indifferently, even when, as on this August morning, a submarine was lying on the horizon, planning to make her its prey.
As soon as the disguised merchantman spotted this enemy she began to behave in character. When an armed merchant ship got within range of a submarine on the surface she frequently let fly a shot on the chance of a hit. That was therefore the proper thing for the Dunraven to do; it was really all a part of the game of false pretence in which she was engaged. However, she took pains that the shell should not reach the submarine; this was her means of persuading the U-boat that it outranged the Dunraven's gun and could safely give chase. The decoy merchantman apparently put on extra steam when the submarine started in her direction at top speed; here, again, however, the proper manœuvre was not to run too fast, for her real mission was to get caught. On the other hand, had she slowed down perceptibly, that in itself would have aroused suspicion; her game, therefore, was to decrease speed gradually so that the U-boat would think that it was overtaking its enemy by its own exertions. All during this queer kind of a chase the submarine and the cargo ship were peppering each other with shells, one seriously, the other merely in pretence. The fact that a naval crew, with such a fine target as an exposed submarine, could shoot with a conscious effort not to hit, but merely to lure the enemy to a better position, in itself is an eloquent evidence of the perfect discipline which prevailed in the mystery ship service. Not to aim a fair shot upon the detested vessel, when there was a possibility of hitting it, was almost too much to ask of human nature. But it was essential to success with these vessels never to fire with the intention of hitting unless there was a practical certainty of sinking the submarine; all energies were focussed upon the supreme task of inducing the enemy to expose itself completely within three or four hundred yards of the disguised freighter.