It is not improbable that I have given a false impression concerning the relative merits of the several methods which were developed for fighting the submarine. Destroyers, patrol boats, subchasers, and mystery ships all accomplished great things in solving the most baffling problem presented by the war. The belief is general that the most successful hunter of the submarine was the destroyer, and, so far as absolute figures are concerned, this is true. Destroyers, with their depth charges and their gunfire, sank more U-boats than any other agency. One type of craft, however, proved a more destructive enemy of the submarine than even the destroyer. That was a warship of whose achievements in this direction little has so far been heard. The activities of the German submarine have completely occupied public attention; and this is perhaps the reason why few newspaper readers have suspected that there were other than German and Austrian submarines constantly operating at sea. Everyone has heard of the U-boats, yet how many have heard anything of the H-boats, the E-boats, the K-boats, and the L-boats? The H-, E-, and K-boats were British submarines, and the L-boats were American submarines. In the destruction of the German under-water craft these Allied submarines proved more successful than any kind of surface ship. The Allied destroyers, about 500 in number, sank 34 German submarines with gunfire and depth charges; auxiliary patrol craft, such as trawlers, yachts, and the like, about 3,000 in number, sank 31; while the Allied submarines, which were only about 100 in number, sank 20. Since, therefore, the Allies had about five times as many destroyers as submarines at work, it is evident that the record of the latter vessels surpasses that of the most formidable surface anti-submarine craft.