As already said, the Otranto Strait was an ideal location for this type of anti-submarine craft. It was so narrow—about forty miles—that a force of moderate size could keep practically all of the critical zone under fairly close observation. Above all, the water was so deep—nearly 600 fathoms (3,600 feet)—that a submarine, once picked up by the listening devices, could not escape by the method which was so popular in places where the water was shallow—that of sinking to the bottom and resting there until the excitement was over. On the other hand, this great depth made it very difficult to obstruct the passage by a fixed barrier—a difficulty that was being rapidly overcome by a certain Franco-Italian type of torpedo net. This barrage, after the arrival of our chasers, was so reorganized as to make the best use of their tactical and listening qualities. The several lines of patrolling vessels extended about thirty-five miles; there were vessels of several types, the whole making a formidable gauntlet, which the submarines had to run before they could get from the Adriatic to the Mediterranean. First came a line of British destroyers; it was their main duty to act as protectors and to keep the barrage from being raided by German and Austrian surface ships—a function which they fulfilled splendidly. Next came a line of trawlers, then drifters, motor launches, and chasers, the whole being completed by a line of kite balloon sloops. Practically all these vessels, British as well as American, were provided with the American devices; and so well did these ingenious mechanisms function that it was practically impossible for any submarine to pass through the Otranto barrage in calm weather without being heard. In fact, it became the regular custom for the enemy to wait for stormy weather before attempting to slip through this dangerous area, and even under these conditions he had great difficulty in avoiding detection.
From July, 1918, until the day of the armistice, our flotilla at this point kept constantly at work; and the reports of our commanders show that their sound contacts with the enemy were very frequent. There were battles that unquestionably ended in the destruction of the submarines; just how much we had accomplished, however, we did not know until the Austrians surrendered and our officers, at Cattaro and other places, came into touch with officers of the Austrian navy. These men, who showed the most friendly disposition toward their American enemies, though they displayed the most bitter hostility toward their German allies, expressed their admiration for the work of our subchasers. These little boats, the Austrians now informed us, were responsible for a mutiny in the Austrian submarine force. Two weeks after their arrival it was impossible to compel an Austrian crew to take a vessel through the straits, and from that time until the ending of the war not a single Austrian submarine ventured upon such a voyage. All the submarines that essayed the experiment after this Austrian mutiny were German. And the German crews, the Austrian officers said, did not enjoy the experience any more than their own. There was practically no case in which a submarine crossed the barrage without being bombed in consequence; the moral of the German crews steadily went to pieces, until, in the last month of the war, their officers were obliged to force them into the submarines at the point of a pistol. The records showed, the Austrian high officers said, that the Germans had lost six submarines on the Otranto barrage in the last three months of the war. These figures about correspond with the estimates which we had made; just how many of these the British sank and just how many are to be attributed to our own forces will probably never be known, but the fact that American devices were attached to all the Allied ships on this duty should be considered in properly distributing the credit.
We have evidence—conclusive even though somewhat ludicrous—that the American device on a British destroyer "got" one of these submarines. One dark night this vessel, equipped with the C-tube, had pursued a submarine and bombed it with what seemed to have been satisfactory results. However, I have several times called attention to one of the most discouraging aspects of anti-submarine warfare: that only in exceptional circumstances did we know whether the submarine had been destroyed. This destroyer was now diligently searching the area of the battle, the listeners straining every nerve for traces of her foe. For a time everything was utterly silent; then, suddenly, the listener picked up a disturbance of an unusual kind. The noise rapidly became louder, but it was still something very different from any noise ever heard before. The C-tube consisted of a lead pipe—practically the same as a water pipe—which was dropped over the side of the ship fifteen or twenty feet into the sea; this pipe contained the wires which, at one end, were attached to the devices under the water, and which, at the other end, reached the listener's ears. In a few seconds this tube showed signs of lively agitation. It trembled violently and made a constantly increasing hullabaloo in the ears of the listener. Finally a huge German, dripping with water like a sea lion, appeared over the side of the destroyer and astounded our British Allies by throwing up his arms with "Kamerad!" This visitant from the depths was the only survivor of the submarine which it now appeared had indubitably been sunk. He had been blown through the conning tower, or had miraculously escaped in some other way—he did not himself know just what had taken place—and while floundering around in the water in the inky darkness had, by one of those providences which happen so frequently in war time, caught hold of this tube, and proceeded to pull himself up hand-over-hand until he reached the deck. Had it not been for his escape, the British would never have known that they had sunk the submarine!
This survivor, after shaking off the water, sat down and became very sociable. He did not seem particularly to dislike the British and Americans, but he was extremely bitter against the Italians and Austrians—the first for "deserting" the Germans, the latter for proving bad allies.
"How do you get on with the Italians?" he asked the British officer.
"Very well indeed," the latter replied, giving a very flattering account of the Italian allies.
"I guess the Italians are about as useful to you as the Austrians are to us," the German sea lion replied.
In writing to our officers about this episode, the British commander said:
"We have found a new use for your listening devices—salvaging drowning Huns."
VI