Page:Victory at Sea - William Sowden Sims and Burton J. Hendrick.djvu/266

248 have been unwise to detach these anti-submarine vessels from the area in which they were performing such indispensable service. The overwhelming fact was that we needed all the surface craft we could assemble for the convoy system. The destroyers which we had available for this purpose were entirely inadequate ; to have diverted any of them for other duties would at that time have meant destruction to the Allied cause. The object of placing the barrage so far north was to increase the enemy's difficulty in attempting to sweep a passage through it and facilitate its defence by our forces. The impossibility of defending a mine barrier placed too far south was shown by experience in that area of the North Sea which was known as the "wet triangle." By April, 1917, the British had laid more than 30,000 mines in the Bight of Heligoland, and were then increasing these obstructions at the rate of 3,000 mines a month. Yet this vast explosive field did not prevent the Germans from sending their submarines to sea. The enemy sweepers were dragging out channels through the minefields almost as rapidly as the British were putting new fields down; we could not prevent this, because protecting vessels could not remain so near the German bases without losses from submarine attacks. Moreover, the Germans also laid mines in the same area in order to trap the British mine-layers; and these operations resulted in very considerable losses on each side. These impediments made the egress of a submarine a difficult and nerve-racking process; it sometimes required two or three days and the assistance of a dozen or so surface vessels to get a few submarines through the Heligoland Bight into open waters. Several were unquestionably destroyed in the operation, yet the activity of submarines in the Atlantic showed that these mine-fields had by no means succeeded in proving more than a harassing measure. It was estimated that the North Sea barrage would require about 400,000 mines, far more than existed in the world at that time, and far more than all our manufacturing resources could then produce within a reasonable period. I have already made the point, and I cannot make it too frequently, that time is often the essential element in war—and in this case it was of vital importance. Whether a programme is a wise one or not depends not only upon the feasibility of the plan itself, but upon the time and the circumstances in which it is proposed. In