For this reason it is desirable to repeat and emphasize that the most important accomplishment of the mystery ships was not the actual sinking of submarines, but their profound influence upon the tactics of the U-boats. It was manifest in the beginning that the first information reaching Germany concerning the mystery ships would greatly diminish the chances of sinking submarines by this means, for it would cause all submarines to be wary of all mercantile craft. They were therefore obliged largely to abandon the easy, safe, and cheap methods of sinking ships by bombs or gun fire, and were consequently forced to incur the danger of attacking with the scarce and expensive torpedo. Moreover, barring the very few vessels that could be sunk by long-range gun fire, they were practically restricted to this method of attack on pain of abandoning the submarine campaign altogether. CHAPTER VI AMERICAN COLLEGE BOYS AND SUBCHASERS I Who would ever have thought that a little wooden vessel, displacing only sixty tons, measuring only 110 feet from bow to stern, and manned by officers and crew very few of whom had ever made an ocean voyage, could have crossed more than three thousand miles of wintry sea, even with the help of the efficient naval officers and men who, after training there, convoyed and guided them across, and could have done excellent work in hunting the submarines? We built nearly 400 of these little vessels in eighteen months; and we sent 170 to such widely scattered places as Plymouth, Queenstown, Brest, Gibraltar, and Corfu. Several enemy submarines now lie at the bottom of the sea as trophies of their offensive power; and on the day that hostilities ceased, the Allies generally recognized that this tiny vessel, with the "listening devices" which made it so efficient, represented one of the most satisfactory direct "answers" to the submarine which had been developed by the war. Had it not been that the war ended before enough destroyers could be spared from convoy duty to assist, with their greater speed and offensive power, hunting groups of these tiny craft, it is certain that they would soon have become a still more important factor in destroying submarines and interfering with their operations.