While opinions may differ to a certain extent as to the influence exerted upon the campaign by the various forms of tactics, the means and weapons employed, and the general strategy adopted, I have given what I believe to be a consensus of the best informed opinion upon these matters; and I have taken advantage of all of the information now available to insure accuracy in the account of the conditions that confronted the European naval forces, and in the description of the various operations that have been selected as typical examples of this very extraordinary warfare. It is probably unnecessary to add that this book is published with the full approval of the Navy Department. My correspondence on this subject with the Secretary will be found in the Appendix. W. S. S. CONTENTS CHAPTER PAGE I. WHEN GERMANY WAS WINNING THE WAR 1 II. THE RETURN OF THE "MAYFLOWER" 40 III. THE ADOPTION OF THE CONVOY 78 IV. AMERICAN DESTROYERS IN ACTION 99 V. DECOYING SUBMARINES TO DESTRUCTION 141 VI. AMERICAN COLLEGE BOYS AND SUBCHASERS 168 VII. THE LONDON FLAGSHIP 204 VIII. SUBMARINE AGAINST SUBMARINE 224 IX. THE AMERICAN MINE BARRAGE IN THE NORTH SEA 244 X. GERMAN SUBMARINES VISIT THE AMERICAN COAST 266 XI. FIGHTING SUBMARINES FROM THE AIR 275 XII. THE NAVY FIGHTING ON THE LAND 289 XIII. TRANSPORTING TWO MILLION AMERICAN SOLDIERS TO FRANCE 294 APPENDIX 316 INDEX 347 THE VICTORY AT SEA CHAPTER I WHEN GERMANY WAS WINNING THE WAR I