the passage of submarines were not particularly effective. The British navy knew little about mines in 1914; British naval men had always rather despised them as the "weapons of the weaker power," and it is therefore not surprising that the so-called mine barrage at the Channel crossing was not successful. A large part of it was carried away by the strong tide and storms, and the mines were so defective that oysters and other sea growths, which attached themselves to their prongs, made many of them harmless. In 1918, Admiral Sir Roger Keyes reconstructed this barrage with a new type of mine and transformed it into a really effective barrier; but in the spring of 1917, the German U-boats had little difficulty in slipping through, particularly in the night time. And from this point the distance to the trade routes south and west of Ireland was relatively a short one.

Yet, terribly destructive as these U-boats were, the number which were operating simultaneously in this and in other fields was never very large. The extent to which the waters were infested with German submarines was another particularly ludicrous and particularly prevalent misapprehension. Merchant vessels constantly reported that they had been assailed by "submarines in shoals," and most civilians still believe that they sailed together in flotillas, like schools of fish. There is hardly an American doughboy who did not see at least a dozen submarines on his way across the Atlantic; every streak of suds which was caused by a "tide rip," and every swimming porpoise, was immediately mistaken for the wake of a torpedo; and every bit of driftwood, in the fervid imagination of trans-Atlantic voyagers, immediately assumed the shape of a periscope. Yet it is a fact that we knew almost every time a German submarine slunk from its base into the ocean. The Allied secret service was immeasurably superior to that of the Germans, and in saying this I pay particular tribute to the British Naval Intelligence Department. We always knew how many submarines the Germans had and we could usually tell pretty definitely their locations at a particular time; we also had accurate information about building operations in Germany; thus we could estimate how many they were building and where they were building them, and we could also describe their essential characteristics, and the stage of progress they which had reached at almost any day.

It was not the simplest thing to pilot a submarine out of its base. The Allies were constantly laying mines at these outlets; and before the U-boat could safely make its exit elaborate sweeping operations were necessary. It often took a squadron of nine or ten surface ships, working for several hours, to manœuvre a submarine out of its base and to start it on its journey. For these reasons we could keep a careful watch upon its movements; we always knew when one of our enemies came out; we knew which one it was, and not infrequently we had learned the name of the commander and other valuable details. Moreover, we knew where it went, and we kept charts on which we plotted from day to day the voyage of each particular submarine.

"Why didn't you sink it then?" is the question usually asked when I make this statement—a question which, as I shall show, merely reflects the ignorance which prevails everywhere on the underlying facts of submarine warfare.

Now in this densely packed shipping area, which extended from the north of Ireland to Brest, there were seldom more than eight or ten submarines engaged in their peculiar form of warfare at one time. The largest number which I had any record of was fifteen; and this was an exceptional force; the usual number was four, six, eight, or perhaps ten. Yet the men upon our merchant convoys and troopships saw submarines scattered all over the sea. We estimated that the convoys and troopships reported that they had sighted about 300 submarines for every submarine which was actually in the field. Yet we knew that for every hundred submarines which the Germans possessed they could keep only ten or a dozen at work in the open sea. The rest were on their way to the hunting grounds, or returning, or they were in port being refitted and taking on supplies. Could Germany have kept fifty submarines constantly at work on the great shipping routes in the winter and spring of 1917—before we had learned how to handle the situation—nothing could have prevented her from winning the war. Instead of sinking 850,000 tons in a single month, she would have sunk 2,000,000 or 3,000,000 tons. The fact is that Germany, with all her microscopic preparations for war, neglected to provide herself with the one instrumentality with which she might have won it.

This circumstance, that so few submarines could accomplish such destructive results, shows how formidable was the problem which confronted us. Germany could do this, of course, because the restricted field in which she was able to operate was so constantly and so densely infested with valuable shipping.

In the above I have been describing the operations of the U-boats in the great area to the west and south of Ireland. But there were other hunting fields, particularly that which lay on the east coast of England, in the area extending from Harwich to Newcastle. This part of the North Sea was constantly filled with ships passing between the North Sea ports of England and Norway and Sweden, carrying essential products like lumber and many manufactured articles. Every four days a convoy of from forty to sixty ships left some port in this region for Scandinavia; I use the word "convoy," but the operation was a convoy only in the sense that the ships sailed in groups, for the navy was not able to provide them with an adequate escort—seldom furnishing them more than one or two destroyers, or a few yachts or trawlers. Smaller types of submarines which were known as UB's and UC's and which issued from Wilhelmshaven and the Skager Rack constantly preyed upon this coastal shipping. These submarines differed from the U-boats in that they were smaller, displacing about 350 and 400 tons, and in that they also carried mines, which they were constantly laying. They were much handier than the larger types; they could rush out much more quickly from their bases and get back, and they did an immense amount of damage to this coastal trade. The value of the shipping sunk in these waters was unimportant when compared with the losses which Great Britain was suffering on the great trans-Atlantic routes, but the problem was still a serious one, because the supplies which these ships brought from the Scandinavian countries were essential to the military operations in France.

Besides these two types, the U-boats and the UB's and UC's, the Germans had another type of submarine, the great ocean cruisers. These ships were as long as a small surface cruiser and were half again as long as a destroyer, and their displacement sometimes reached 3,000 tons. They carried crews of seventy men, could cross the Atlantic three or four times without putting into port, and some actually remained away from their bases for three or four months. But they were vessels very difficult to manage; it took them a relatively long time to submerge, and, for this reason, they could not operate around the Channel and other places where the anti-submarine craft were most numerous. In fact, these vessels, of which the Germans had in commission perhaps half a dozen when the armistice was signed, accomplished little in the war. The purpose for which they were built was chiefly a strategic one. One or two were usually stationed off the Azores, not in any expectation that they would destroy much shipping—the fact is that they sank very few merchantmen—but in the hope that they might divert anti-submarine craft from the main theatre of operations. In this purpose, however, they were not successful; in fact, I cannot see