were not sunk was simply because they were not seriously attacked; I have already shown how easily Germany could have sunk them if she had really tried. Any reliance upon armed guards as a protection against submarines would have been fundamentally a mistake, for the additional reason that it was a defensive measure; it must be apparent that the extremely grave situation which we were then facing demanded the most energetic offensive methods. Yet the arming of merchant ships was justified as a minor measure. It accomplished the one important end of forcing the submarine to submerge and to use torpedoes instead of gunfire. In itself this was a great gain; obviously the Germans would much prefer to sink ships with projectiles than with torpedoes, for their supply of these latter missiles was limited.[3] In April, 1917, the British navy was fighting the submarine mainly in two ways: it was constantly sowing mines off the entrance to the submarine bases, such as Ostend and Zeebrugge, and in the Heligoland Bight--operations that accomplished little, for the Germans swept them up almost as fast as they were planted; and it was patrolling the submarine infested area with anti-submarine craft. The Admiralty was depending almost exclusively upon this patrol, yet this, the only means which then seemed to hold forth much promise of defeating the submarine, was making little progress. For this patrol the navy was impressing into service all the destroyers, yachts, trawlers, sea-going tugs, and other light vessels which could possibly be assembled; almost any craft which could carry a wireless, a gun, and depth charges was boldly sent to sea. At this time the vessel chiefly used was the destroyer. The naval war had demonstrated that the submarine could not successfully battle with the destroyer; that any U-boat which came to the surface within fighting range of this alert and speedy little surface ship ran great risk of being sunk. This is the fundamental fact--that the destruction of the submarine was highly probable, in case the destroyer could get a fair chance at her--which regulated the whole anti-submarine campaign. It is evident, therefore, that a proper German strategy would consist in so disposing its submarines that they could conduct their operations with the minimum risk of meeting their most effective enemies, while a properly conceived Allied strategy would consist in so controlling the situation that the submarines would have constantly to meet them. Frankness compels me to say that, in the early part of 1917, the Germans were maintaining the upper hand in this strategic game; they were holding the dominating position in the campaign, since they were constantly attacking Allied shipping without having to meet the Allied destroyers, while the Allied destroyers were dispersing their energies over the wide waste of waters. But the facts in the situation, and not any superior skill on the part