work, it is evident that the record of the latter vessels surpasses that of the most formidable surface anti-submarine craft.
Thus the war developed the fact that the most deadly enemy of the submarine is the submarine itself. Underwater warfare is evidently a disease in which like cures like. In a way this is the most astonishing lesson of the naval operations. It is particularly interesting, because it so completely demolishes all the ideas on this subject with which we entered the war. From that day in history when the submarine made its first appearance, the one quality which seemed to distinguish it from all other kinds of warship was that it could not be used to fight itself. Writers were fond of pointing out that battleship could fight battleship, that cruiser could fight cruiser, that destroyer could fight destroyer, but that submarine could not fight submarine. This supposed quality, which was constantly emphasized, was what seemed to make the introduction of this strange vessel such a dangerous thing for the British Empire. For more than a hundred years the under-water boat was a weapon which was regarded as valuable almost exclusively to the weaker sea powers. In the course of the nineteenth century this engine of sea fighting made many spectacular appearances; and significantly it was always heralded as the one effective way of destroying British domination at sea.
The inventor of the modern submarine was an undergraduate of Yale named David Bushnell; his famous Turtle, according to the great British authority, Sir William White, formerly Chief Naval Constructor of the British navy, contained every fundamental principle of "buoyancy, stability, and control of depth " which are found in the modern submarine; "it cannot be claimed," he said in 1905, "that any new principle of design has been discovered or applied since Bushnell.... He showed the way to all his successors. . . . Although alternative methods of fulfilling essentials have been introduced and practically tested, in the end Bushnell's plans in substance have been found the best." The chief inspiration of Bushnell's work was a natural hostility to Great Britain, which was at that time engaged in war with his own country ; his submarine, invented in 1777, was intended to sink the British warships which were then anchored
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