At a date determined by the same general policy, and somewhat subsequent to the first creation of this mercantile marine, came the decision to build a great fleet. Now, it so happens that Great Britain alone among the Powers of Europe depends for her existence upon supremacy at sea, and particularly upon naval superiority in the Narrow Seas to the east and the south of the British islands. Such a necessity is, of course, a challenge to the rest of the world, and it would be ridiculous to expect the rest of the world to accept that challenge without protest. But a necessity this naval policy of Great Britain remains none the less. The moment some rival or group of rivals can overcome her fleet, her mere physical livelihood is in peril. She cannot be certain of getting her food. She cannot be certain of getting those foreign materials the making up of which enables her to purchase her food. Further, her dominions are scattered oversea, and supremacy at sea is her only guarantee of retaining the various provinces of her dominion. It is a case which has happened more than once before in the history of the world. Great commercial seafaring States have arisen; they have always had the same method of government by a small, wealthy class, the same ardent patriotism, the same scattered empire, and the same inexorable necessity of maintaining supremacy at sea. Only one Power had hitherto rendered this country anxious for the Narrow Seas: that Power was France, and it only controlled one-half of the two branches of the Narrow Seas, the North Sea and the Channel. It had been for generations a cardinal piece of English policy that the French Fleet should be watched, the English Fleet maintained overwhelmingly superior to it, and all opportunities for keeping France engaged with other rivals used to the advantage of this country. On this account English policy leant, on the whole, towards the German side, during all the generation of rivalry between France and Germany which followed the war of 1870.