Another circumstance which made the barrage a feasible enterprise was that by the last of the year 1917 it was realized that the submarine had ceased to be a decisive factor in the war. It still remained a serious embarrassment, and every measure which could possibly thwart it should be adopted. But the writings of German officers which have been published since the war make it apparent that they themselves realized early in 1918 that they would have to place their hopes of victory on something else besides the submarine. The convoy system and the other methods of fighting under-water craft which I have already described had caused a great decrease in sinkings. In April of 1917 the losses were nearly 900,000 tons; in November of the same year they were less than 300,000 tons.[7] Meanwhile, the construction of merchant shipping, largely a result of the tremendous expansion of American shipbuilding facilities, was increasing at a tremendous rate. A diagram of these, the two essential factors in the submarine campaign, disclosed such a rapidly rising curve of new shipping, and such a rapidly falling curve of sinkings, that the time could be easily foreseen when the net amount of Allied shipping, after the submarines had done their worst, would show a promising increase. But, as stated above, the submarines were still a distinct menace; they were still causing serious losses; and it was therefore very important that we should leave no stone unturned toward demonstrating beyond a shadow of doubt that warfare as conducted by these craft could be entirely put down. The more successfully we demonstrated this fact and the more energetically we prosecuted every form of opposition, the earlier would the enemy's general _moral_ break down and victory be assured. In war, where human lives as well as national interests are at stake, no thought whatever can be given to expense. It is impossible to place a value on human life. Therefore, on November 2, 1917, the so-called "Northern Barrage" project was officially adopted by both the American and the British Governments. When I say that the proposed mine-field was as long as the distance from Washington to New York, some idea of its magnitude may be obtained. Nothing like it had ever been attempted before. The combined operations involved a mass of detail which the lay mind can hardly comprehend. The cost--$40,000,000--is perhaps not an astonishing figure in the statistics of this war, but it gives some conception of the size of the undertaking. II