—things which did not figure in the early designs of submarines—one boat could decline the combat simply by
submerging. In the minds of Fulton and Holland an engagement between such craft would reduce itself to
mutual attempts to ram each other under the water, and many fanciful pictures of the early days portrayed exciting
deep-sea battles of this kind, in which submarines, looking like mighty sea monsters, provided with huge glaring
headlights, made terrific lunges at each other. None of the inventors foresaw that, in such battles as would
actually take place, the torpedo would be used, and that the submarine which was defeated would succumb to one
of those same stealthy attacks which it was constantly meditating against surface craft.
Another point of the highest importance is that in a conflict of submarine against submarine the Allied boats had one great advantage over the German. Hans Rose and Valentiner and Moraht and other U-boat commanders, as already explained, had to spend most of their time on the surface in order to keep their batteries fully supplied with electricity, in readiness for the dives that would be necessary when the Allied destroyers approached. But the Allied submarine commander did not have to maintain this constant readiness; the reason, it is hardly necessary to say, is that the Allied submarine had no surface enemies, for there were no German surface craft operating on the high seas; the Grand Fleet at Scapa Flow was carefully attending to that very essential detail. Occasionally, indeed, our submarines were attacked by our own destroyers, but accidents of this kind, though uncomfortably frequent, were not numerous enough to interfere with the operation I have in mind. The statement seems almost like a contradiction in terms, yet it is entirely true, that, simply because the Allied submarines did not have to hold themselves constantly ready to submerge, they could in fact spend a considerable part of their time under the water, for they were not compelled to economize electric power so strictly. This gave them a great advantage in hunting the U-boats. British and American submarines could fully charge their batteries, drop under water and cruise around with enough speed to maintain a horizontal position at "periscope depth," that is, a depth just sufficient to enable them to project
