Yet there was no mystery about the immunity which these great fighting vessels were enjoying; the submarine problem, so far as it affected the battle fleet, had already been solved. The explanation was found in the simple circumstance that, whenever the dreadnoughts went to sea, they were preceded by a screen of cruisers and destroyers. It almost seemed as though these surface craft were serving as a kind of impenetrable wall against which the German U-boats were beating themselves in vain. Yet to the casual observer there seemed to be no reason why the submarines should stand in any particular terror of the destroyers. Externally they looked like the least impressive war vessels afloat. When they sailed ahead of the battle squadrons, the destroyers were ungraceful objects upon the surface of the water; the impression which they conveyed was that of fragility rather than of strength, and the idea that they could ever be the guardians of the mighty battleships which sailed behind them at first seemed almost grotesque. Yet these little vessels really possessed the power of overcoming the submarine. The war had not progressed far when it became apparent that the U-boat could not operate anywhere near this speedy little surface vessel without running serious risk of destruction. Until the reports of submarine fighting began to find their way into the papers, however, the destroyer was probably the one type of warship in which the public had the smallest interest. It had become, indeed, a kind of ugly duckling of the Navy. Our Congress had regularly neglected it; year after year our naval experts had recommended that four destroyers be built for every battleship, and annually Congress had appropriated for only one or two. The war had also found Great Britain without a sufficient number of destroyers for the purpose of anti-submarine warfare. The Admiralty had provided enough for screening the Grand Fleet in cruising and in battle, but it had been called upon to divert so many for the protection of troop transportation, supply ships, and commerce generally that the efficiency of the fleet had been greatly undermined. Thus Britain found herself without enough destroyers to meet the submarine campaign; this situation was not due to any lack of foresight, but to a failure to foresee that any civilized nation could ever employ the torpedo in unrestricted warfare against merchant ships and their crews.