We Americans had seven submarines based on Berehaven, Ireland, whose "billets" were located in the approaches to the Irish Sea. The most spectacular achievement of any one of our boats was a curious mix-up with a German submarine, the details of which have never been accurately ascertained, but the practical outcome of which was indisputably the sinking of the German boat. After a week's hard work on patrol, the A L-2 was running back to her base on the surface when the lookout sighted a periscope. The A L-2 at once changed her course, the torpedo was made ready to fire, when the quiet of the summer afternoon was rent by a terrific roar and explosion. It was quite apparent that something exceedingly distressing had happened to the German submarine; the American turned, and made a steep dive, in an attempt to ram the enemy, but failed. Listening with the hydrophone, the A L-2 could hear now the whirring of propellers, which indicated that the submarine was attempting to gain surface and having difficulty in doing so, and now and then the call letters of the German under-water signal set, which seemed to show that the vessel was in distress and was sending appeals for aid. According to the Admiralty records, a German submarine operating in that area never returned to port; so it seems clear enough that this German was lost. Commander R. C. Grady, who commanded the American submarine division, believes that the German spotted the American boat before it was itself seen, that it launched a torpedo, that this torpedo made an erratic course (a not infrequent trick of a torpedo) around our ship, returned and hit the vessel from which it started. There are others who think that there were two German submarines in the neighbourhood, that one fired at our boat, missed it, and that its torpedo sped on and struck its mate. Probably the real facts about the happening will never be explained.
Besides the actual sinkings to their credit, the Allied submarines accomplished strategic results of the utmost importance. We had reason to believe that the Germans feared them almost more than any other agency, unless it was the mine. "We got used to your depth charges," said the commander of a captured submarine, "and did not fear them; but we lived in constant dread of your submarines. We never knew what moment a torpedo was going to hit us." So greatly did the Germans fear this attack that they carefully avoided the areas in which the Allied under-water boats were operating. We soon learned that we could keep any section free of the Germans which we were able to patrol with our own submarines. It also soon appeared that the German U-boats would not fight our subsurface vessels. At first this may seem rather strange; certainly a combat between two ships of the same kind, size, and armament would seem to be an equal one; the disinclination of the German to give battle under such conditions would probably strike the layman as sheer cowardice. But in this attitude the Germans were undoubtedly right.
The business of their submarines was not to fight warships; it was exclusively to destroy merchantmen. The demand made upon the U-boat commanders was to get "tonnage! tonnage!" Germany could win the war in only one way: that was by destroying Allied shipping to such an extent that the Allied sea communications would be cut, and the supplies of men and munitions and food from the United States shut off. For this tremendous task Germany had an inadequate number of submarines and torpedoes. Only by economizing to the utmost extent on these vessels and these weapons could she entertain any hope of success. Had Germany possessed an unlimited quantity of submarines and torpedoes, she might perhaps have profitably expended some of them in warfare on British "H-boats" and American "L-boats"; or, had there been a certainty of "getting" an Allied submarine with each torpedo fired, it would have been justifiable to use these weapons, small as was the supply. The fact was, however, that the Allies expended many torpedoes for every submarine sunk; and this was clearly a game which Germany could not afford to play. Evidently the U-boats had orders to slip under the water whenever an Allied submarine was seen; at least this was the almost invariable procedure. Thus the Allied submarines compelled their German enemies to do the one thing which worked most to their disadvantage: that is, to keep submerged when in the same area with our submarines; this not only prevented them from attacking merchantmen, but forced them to consume their electric power, which, as I have already explained, greatly diminished their efficiency as attacking ships.
The operations of Allied submarines also greatly diminished the value of the "cruiser" submarines which Germany began to construct in 1917. These great subsurface vessels were introduced as an "answer" to the convoy system. The adoption of the convoy, as I have already explained, made it ineffective for the Germans to hunt far out at sea. Until the Allies had put this plan into operation, the relatively small German U-boats could go two or three hundred miles into the Atlantic and pick off almost at will the merchant ships, which were then proceeding alone and unescorted. But now the destroyers went out to a point two or three hundred miles from the British coast, formed a protecting screen around the convoy, and escorted the grouped ships into restricted waters. The result of this was to drive the submarines into these coastal waters; here again, however, they had their difficulties with destroyers, subchasers, submarines, and other patrol craft. It will be recalled that no destroyer escort was provided for the merchant convoys on their way across the Atlantic; the Allies simply did not have the destroyers for this purpose. The Germans could not send surface raiders to attack these convoys in mid-ocean, first, because their surface warships could not escape from their ports in sufficient numbers to accomplish any decisive results, and, secondly, because Allied surface warships accompanied every convoy to protect them against any such attack. There was only one way in which the Germans could attack the convoys in mid-ocean. A fleet of great ocean-going submarines, which could keep the sea for two or three months, might conceivably destroy the whole convoy system at a blow. The scheme was so obvious that Germany in the summer of 1917 began building ships of this type. They were about 300 feet long, displaced about 3,000 tons, carried fuel and supplies enough to maintain themselves for three or four months from their base, and, besides torpedoes, had six-inch guns that could outrange a destroyer. By the time the armistice was signed Germany had built about twenty of these ships. But they possessed little offensive value against merchantmen. The Allied submarines and destroyers kept them from operating in the submarine zone. They are so difficult to manœuvre that not only could they not afford to remain in the neighbourhood of our anti-submarine craft, but they were not successful in attacking merchant vessels. They never risked torpedoing a convoy, and rarely even a single vessel, but captured a number by means of their superior gunfire. These huge "cruiser submarines," which aroused such fear in the civilian mind when the news of their existence first found its way into print, proved to be the least harmful of any of the German types.
The Allied submarines accomplished another result of the utmost importance. They prevented the German U-boats from hunting in groups or flotillas. All during 1917 and 1918 the popular mind conjured up frightful pictures of U-boat squadrons, ten or fifteen together, lying in wait for our merchantmen or troopships. Hardly a passenger crossed the ocean without seeing a dozen German submarines constantly pursuing his ship. In a speech which I made to a group of American editors who visited England in September, 1918, I touched upon this point. "I do not know," I told these journalists, "how many submarines you gentlemen saw on the way over here, but if you had the usual experience, you saw a great many. I have seen many accounts in our papers on this subject. If you were to believe these accounts, you could only conclude that many vessels have crossed the ocean with difficulty because submarines were so thick that they scraped all the paint off the vessels' sides. All of these accounts are, of course, unofficial. They get into the American papers in various ways. It is to be regretted that they should be published and thereby give a false impression. Some time ago I saw a letter from one of our men who came over here on a ship bound into the English Channel. This letter was written to his girl. He said that he intended to take the letter on shore and slip it into a post box so that the censor should not see it. The censor did see it and it eventually came to me. This man was evidently intent on impressing on his girl the dangers through which he had passed. It related that the vessel on which he had made the voyage had met two or three submarines a day; that two spies were found on board and hanged; and it said, 'When we arrived off our port there were no less than eighteen submarines waiting for us. Can you beat it?'"
Perhaps in the early days of the war the German U-boats did hunt in flotillas; if so, however, they were compelled to abandon the practice as soon as the Allied submarines began to operate effectively. I have already indicated the circumstances which reduced their submarine operations to a lonely enterprise. In the open sea it was impossible to tell whether a submarine was a friend or an enemy. We never knew whether a submarine on the surface was one of our own or a German; as a result, as already said, we gave orders to attack any under-water boat, unless we had absolute knowledge that it was a friend. Unquestionably the Germans had the same instructions. It would therefore be dangerous for them to attempt to operate in groups, for they would have no way of knowing that their supposed associate was not an Allied or an American submarine. Possibly, even after our submarines had become exceedingly active, the Germans may have attempted to cruise in pairs; one explanation of the strange adventure of the A L-2, as said above, was that there were two U-boats in the neighbourhood; yet the fact remains that there is no well-established case on record in which they did so. This circumstance that they had to operate singly was a strategic point greatly to our advantage, especially, as I shall describe, when we began transporting American troops.