There is no doubt that the German submarine service had everything in its favour. They had targets in plenty, in view of the fact that our fleet kept the sea practically continuously at the beginning of the war, and for about 25 per cent, of the time during the later stages. The coasts of these islands are ideal for submarines to work round; the shore is mostly steep-to, and the high landmarks make navigation easy. The German coast is low and difficult to see; it is guarded by outlying shoals and islands, and the visibility off-shore is usually poor; the numerous rivers emptying into the Bight make diving conditions bad at times owing to the alternate strata formed of fresh and salt water. Altogether, the two sets of conditions used to make our submarine service often wish that the two belligerent navies might change fleets, bases, and strategic problems, and so give our boats a chance to show how a weaker navy should carry out a war of attrition. Such a war could undoubtedly have been fought very much more efficiently by the enemy if he had concentrated on warship-targets only. There is a clause in a German instructional book for submarine officers which directs the young idea to "never attack a man-of-war if there is chance of usefully attacking commerce" (or words to that effect). That sort of order is an admission of defeat, as although the axiom, that "the object of strategy is the defeat of the main forces of the enemy," was, I believe, laid down by Napoleon, it is as old as the time of the first battle between tribes of Palæolithic men. A defeat of the Grand Fleet by direct naval action would have given Germany domination of the world; but the works of the late Admiral Mahan do not seem to have been understood in Berlin. The great German commerce-destroying submarine navy is now no more. Its fate will be a reminder to strategists of the future that a _guerre de course_ never won a war yet, and that there is no easy road to victory. It may be easier "to attack merchant ships rather than men-of-war," but if the result is the surrender of one's own Navy, the policy seems hardly profitable. However, our own submarine strategy was, in spite of the enemy's example, kept on correct lines; our leaders saw the possibilities and the future of this type of craft far more clearly than did Admiral Tirpitz. Our boats were built and used for military purposes only, and their work was all part of the main strategical policy of the Navy. IV I