For, I must repeat, the German navy could maintain in the open Atlantic an average of only about eight or ten of her efficient U-boats at one time. The German Admiralty thus had to answer this difficult question: Shall we use these submarines to attack mercantile convoys or to attack troop convoys? The submarine flotilla which was actively engaged was so small that it was absurd to think of sending half into each lane; the Germans must send most of their submarines against cargo ships or most of them against troopships. Which should it be? If it were decided to concentrate on mercantile vessels then the American armies, which the German chiefs had declared to their people could never get to the Western Front, would reach France and furnish General Foch the reserves with which he might crush the German armies before winter. If, on the other hand, the Germans should decide to concentrate on troopships, then the food and supplies which were essential to the Allied cause would flow at an even greater rate into Great Britain and thence to the European nations. Whether it were more important, in a military sense, to cut the Allies' commercial lines of communication or to sink troop transports is an interesting question. It is almost impossible for the Anglo-Saxon mind to consider this as a purely military matter, apart from the human factors involved. The sinking of a great transport, with 4,000 or 5,000 American boys on board, would have been a dreadful calamity and would have struck horror to the American people; it was something which the Navy was determined to prevent, and which we did prevent. Considered as a strictly military question, however--and that was the only consideration which influenced the Germans--it is hard to see how the loss of one transport, or even the loss of several, would have materially affected the course of the war. In judging the purely military results of such a tragedy, we must remember that the Allied armies were losing from 3,000 to 5,000 men a day; thus the sinking of an American transport once a week would not have particularly affected the course of the war. The destruction of merchant shipping in large quantities, however, represented the one way in which the Germans could win. There were at least a hundred merchant ships to every one of our troopships; if a considerable number of the former could be sunk, Germany would have scored a decisive advantage. From the declaration of submarine warfare, the objective of the German Admiralty had been for "tonnage"; by March, 1918, as already said, the chances of destroying sufficient tonnage to win had become extremely slight; yet it still represented the one logical mission of the submarine.