up in more practical form, but in 1917 the idea was not among the possibilities there were not mines enough in the world to build such a barrage, nor had a mine then been invented that was suitable for the purpose.
The belief prevailed in the United States, and, to a certain extent, in England itself, that the most effective means of meeting the submarine was to place guns and gun crews on all the mercantile vessels. Even some of the old British merchant salts maintained this view. "Give us a gun, and we'll take care of the submarines all right," they kept saying to the Admiralty. But the idea was fundamentally fallacious. In the American Congress, just prior to the declaration of war, the arming of merchant ships became a great political issue; scores of pages in the Congressional Record are filled with debates on this subject, yet, so far as affording any protection to shipping was concerned, all this was wasted oratory. Those who advocated arming the merchant ships as an effective method of counteracting submarine campaigns had simply failed to grasp the fundamental elements of submarine warfare. They apparently did not understand the all-import ant fact that the quality which makes the submarine so difficult to deal with is its invisibility. The great political issue which was involved in the submarine controversy, and the issue which brought the United States into the war, was that the Germans were sinking merchant ships without warning. And it was because of this very fact this sinking without warning that a dozen guns on a merchant ship afforded practically no protection. The look-out on a merchantman could not see the submarine, for the all-sufficient reason that the submarine was concealed beneath the water; it was only by a happy chance that the most penetrating eye could detect the periscope, provided that one were exposed. The first intimation which was given the merchantman that a U-boat was in his neighbourhood was the explosion of the torpedo in his hull. In six weeks, in the spring and early summer of 1917, thirty armed merchantmen were torpedoed and sunk off Queenstown, and in no case was a periscope or a conning-tower seen. The English never trusted their battleships at sea without destroyer escort, and certainly if a battleship with its powerful armament could not protect itself from submarines, it was
