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 accomplish this by sending a submarine to attack our shipping off New York and Boston and other Atlantic seaports, and possibly even to bombard our harbours. The Germans doubtless believed that they might create such alarm and arouse such public clamour in the United States that our destroyers and other anti-submarine craft would be kept over here by the Navy Department, in response to the popular agitation to protect our own coast. This is the reason why American headquarters in London, and the Allied admiralties, expected such a visitation. The Germans obviously endeav-
