would not have served the purpose of a base at all. Comparatively few of the German submarines could have made the cruise to the American coast and operated successfully there so far away from their bases for any considerable time. In the time spent in such an enterprise, the same submarine could make three or four trips in the waters about the British Isles, or off the coast of France, and could sink four or five times the tonnage which could be destroyed in the cruise on the Atlantic coast. In the eastern Atlantic, the submarine could seek its victims in an area comprising a comparatively few square miles, at points where shipping was so dense that a submarine had only to take a station and lie in wait, and be certain, within a short time, of encountering valuable ships which it could attack successfully with its torpedoes. If the U-boats should be sent to America, on the other hand, they would have to patrol up and down three thousand miles of coast, looking for victims; and even when they found them the ships that they could sink would usually be those engaged in the coastwise traffic, which were of infinitely less military importance than the transports which were carrying food, munitions, and supplies to the Allies and which were being sunk in the eastern Atlantic. Anything resembling an attack in force on American harbours was therefore improbable. Yet it seemed likely from the first that the Germans would send an occasional submarine into our waters, as a measure of propaganda rather than for the direct military result that would be achieved. American destroyers and other vessels were essential to the success of the whole anti-submarine campaign of the Allies. The sooner they could all be sent into the critical European waters the sooner the German campaign of terrorism would end. If these destroyers, or any considerable part of them, could be kept indefinitely in American waters, the Germans might win the war. Any manoeuvre which would have as its result the keeping of these American vessels, so indispensable to the Allies, out of the field of active warfare, would thus be more than justified and, indeed, would indicate the highest wisdom on the part of the German navy. The Napoleonic principle of dividing your enemy's forces is just as valuable in naval as in land warfare. For many years Admiral Mahan had been instructing American naval officers that the first rule in warfare is not to divide your fighting forces, but always to keep them together, so as to bring the whole weight at a given moment against your adversary. Two of the fundamental principles of the science of warfare, on land and sea alike, are contained in the maxims: Keep your own forces concentrated, and always endeavour to divide those of the enemy. Undoubtedly, the best method which Germany could use to keep our destroyers in our own waters would be to make the American people believe that their lives and property were in danger; they might