IV
A description of a few actual convoys, and the experiences of our destroyers with them, will perhaps best make clear the nature of the mechanism which protected the world's shipping. For this purpose I have selected typical instances which illustrate the every-day routine experiences of escorting destroyers, and other experiences in which their work was more spectacular.
One day in late October, 1917, a division of American destroyers at Queenstown received detailed instructions from Admiral Bayly to leave at a certain hour and escort the outward convoy "O Q 17" and bring into port the inbound convoy "H S 14." These detailed instructions were based upon general instructions issued from the Admiralty, where my staff was in constant attendance and co-operation. The symbols by which these two groups of ships were designated can be easily interpreted. The O Q simply meant that convoy "No. 17"—the seventeenth which had left that port—was Outward bound from Queenstown, and the H S signified that convoy "No. 14" was Homeward bound from Sydney, Cape Breton. Queenstown during the first few months was one of those places at which ships, having discharged their cargoes, assembled in groups for despatching back to the United States. Later Milford Haven, Liverpool, and other ports were more often used for this purpose. Vessels had been arriving here for several days from ports of the Irish Sea and the east coast of England. These had now been formed into convoy "O Q 17"; they were ready for a destroyer escort to take them through the submarine zone and start them on the westward voyage to American ports.
This escort consisted of eight American destroyers and one British "special service ship"; the latter was one of that famous company of decoy vessels, or "mystery ships," which, though to all outward appearances unprotected merchantmen, really carried concealed armament of sufficient power to destroy any submarine that came within range. This special service ship, the Aubrietia, was hardly a member of the protective escort. Her mission was to sail about thirty miles ahead of the convoy; when observed from the periscope or the conning-tower of a submarine, the Aubrietia seemed to be merely a helpless merchantman sailing alone, and as such she presented a particularly tempting target to the U-boat. But her real purpose in life was to be torpedoed. After landing its missile in a vessel's side, the submarine usually remained submerged for a period, while the crew of its victim was getting off in boats; it then came to the surface, and the men prepared to board the disabled ship and search her for valuables and delicacies, particularly for information which would assist them in their campaign, such as secret codes, sailing instructions, and the like. The mystery ship had been preparing for this moment, and as soon as the submarine broke water, the gun ports of the disguised merchantman dropped, and her hitherto concealed guns began blazing away at the German. By October, 1917, these special service ships had already accounted for several submarines; and it had now become a frequent practice to attach one or more to a convoy, either ahead, where she might dispose of the submarine lying in wait for the approaching aggregation, or in the rear, where a U-boat might easily mistake her for one of those stragglers which were an almost inevitable part of every convoy.
Trawlers and mine-sweepers, as was the invariable custom, spent several hours sweeping the Queenstown Channel before the sailing of convoy "O Q 17" and its escort. Promptly at the appointed time the eight American ships sailed out in "Indian file," passing through the net which was always kept in place at the entrance to the harbour. Their first duty was to patrol the waters outside for a radius of twelve miles; it was not improbable that the Germans, having learned that this convoy was to sail, had stationed a submarine not far from the harbour entrance. Having finally satisfied himself that there were no lurking enemies in the neighbourhood, the commander of the destroyer flagship signalled to the merchant ships, which promptly left the harbour and entered the open sea. The weather was stormy; the wind was blowing something of a gale and head seas were breaking over the destroyers' decks. But the convoy quickly manœuvred into three columns, the destroyers rapidly closed around them, and the whole group started for "Rendezvous A"—this being the designation of that spot on the ocean's surface where the fourteenth meridian of longitude crosses the forty-ninth parallel of latitude—a point in the Atlantic about three hundred miles south-west of Queenstown, regarded at that time as safely beyond the operating zone of the submarine. Meanwhile, the "mystery ship," sailing far ahead, disappeared beneath the horizon.
Convoying ships in the stormy autumn and winter waters, amid the fog and rain of the eastern Atlantic, was a monotonous and dreary occupation. Only one or two incidents enlivened this particular voyage. As the Parker, Commander Halsey Powell, was scouting ahead at about two o'clock in the afternoon, her lookout suddenly sighted a submarine, bearing down upon the convoy. Immediately the news was wirelessed to every vessel. As soon as the message was received, the whole convoy, at a signal from the flagship, turned four points to port. For nearly two hours the destroyers searched this area for the submerged submarine, but that crafty boat kept itself safely under the water, and the convoy now again took up its original course. About two days' sailing brought the ships to the point at which the protecting destroyers could safely leave them, as far as submarines were concerned, to continue unescorted to America; darkness had now set in, and, under its cover, the merchantmen slipped away from the warships and started westward. Meantime, the destroyer escort had received a message from the Cumberland, the British cruiser which was acting as ocean escort to convoy "HS 14." "Convoy is six hours late," she reported, much like the announcer at a railroad station who informs the waiting crowds that the incoming train is that much overdue. According to the schedule these ships should reach the appointed rendezvous at six o'clock the next morning; this message evidently moved the time of arrival up to noon. The destroyers, slowing down so that they would not arrive ahead of time, started for the designated spot.
Sometimes thick weather made it impossible to fix the position by astronomical observations, and the convoy might not be at its appointed rendezvous. For this reason the destroyers now deployed on a north and south line about twenty miles long for several hours. Somewhat before the appointed time one of the destroyers sighted a faint cloud of smoke on the western horizon, and soon afterward thirty-two merchantmen, sailing in columns of fours, began to assume a definite outline. At a signal from this destroyer the other destroyers of the escort came in at full speed and ranged themselves on either side of the convoy—a manœuvre that always excited the admiration of the merchant skippers. This mighty collection of vessels, occupying about ten or twelve square miles on the ocean, skilfully maintaining its formation, was really a beautiful and inspiring sight. When the destroyers had gained their designated positions on either side, the splendid cavalcade sailed boldly into the area which formed the favourite hunting grounds for the submarine.
As soon as this danger zone was reached the whole aggregation, destroyers and merchant ships, began to zigzag. The commodore on the flagship hoisted the signal, "Zigzag A," and instantaneously the whole thirty-two ships began to turn twenty-five degrees to starboard. The great ships, usually so cumbersome, made this simultaneous turn with all the deftness, and even with all the grace of a school of fish into which one has suddenly cast a stone. All the way across the Atlantic they had been practising such an evolution; most of them had already sailed through the danger zone more than once, so that the manœuvre was by this time an old story. For ten or fifteen minutes they proceeded along this course, when immediately, like one vessel, the convoy turned twenty degrees to port, and started in a new direction. And so on for hours, now a few minutes to the right, now a few minutes to the left, and now again straight ahead, while all the time the destroyers were cutting through the water, every eye of the skilled lookouts in each crew fixed upon the surface for the first glimpse of a periscope. This zigzagging was carried out according to comprehensive plans which enabled the convoy to zigzag for hours at a time without signals, the courses and the time on each course being designated in the particular plan ordered, all ships' clocks being set exactly alike by time signal. Probably I have made it clear why these zigzagging evolutions constituted such a protective measure. All the time the convoy was sailing in the danger zone it was assumed that a submarine was present, looking for a chance to torpedo. Even though the officers might know that there was no submarine within three hundred miles, this was never taken for granted; the discipline of the whole convoy system rested upon the theory that the submarine was there, waiting only the favourable moment to start the work of destruction. But a submarine, as already said, could not strike without the most thorough preparation. It must get within three or four hundred yards or the torpedo would stand little chance of hitting the mark in a vital spot. The commander almost never shot blindly into the convoy, on the chance of hitting some ship; he carefully selected his victim; his calculation had to include its speed, the speed of his own boat and that of his torpedo; above all, he had to be sure of the direction in which his intended quarry was steaming; and in this calculation the direction of the merchantman formed perhaps the most important element. But if the ships were constantly changing their direction, it is apparent that the submarine could make no calculations which would have much practical value.
In the afternoon the Aubrietia, the British mystery ship which was sailing thirty miles ahead of the convoy, reported that she had sighted a submarine. Two or three destroyers dashed for the indicated area, searched it thoroughly, found no traces of the hidden boat, and returned to the convoy. The next morning six British destroyers and one cruiser arrived from Devonport. Up to this time the convoy had been following the great "trunk line" which led into the Channel, but it had now reached the point where the convoys split up, part going to English ports and part to French. These British destroyers had come to take over the twenty ships which were bound for their own country, while the American destroyers were assigned to escort the rest to Brest. The following conversation—typical of those that were constantly filling the air in that area—now took place between the American flagship and the British:
Conyngham to Achates: This is the Conyngham, Commander Johnson. I would like to keep the convoy together until this evening. I will work under your orders until I leave with convoy for Brest.