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.