But the first effect of coal was not to usher in the good life but to intensify the ancient struggle, widening its stage from pocketed civilizations to the world. For more than a hundred and fifty years, the abundant and readily accessible coal of Great Britain made her the protagonist in the world drama. Her acquisitive instinct, charged with cosmic energy, shot lines of imperial expansion out across the seas to America, India, Australia, China, and Africa. Her coal-created wealth enabled her to maintain the mastery of the ocean highways which she had won from Spain and Holland and to hold it against Napoleonic France and later against imperial Germany. It gave her an economic surplus upon the basis of which the consciousness of kind welded her people into one nation and ended the civil wars which from the time of the Danish invasion and the landing of William the Conqueror had kept each little group within the island armed against every other little group. And it transformed her with jarring rapidity into a country that lived by manufacture and by trade and supported a far larger population than could have lived upon the island if it had been merely an agricultural country raising its own food. In order that this swelling population might go on getting coal out of the mines and turning out products from the factories it must be adequately and cheaply fed. The place where its food came from was chiefly America. During the hundred and fifty years of England's primacy, America was not only her granary but increasingly the granary of other nations, and the great reservoir for all their overflowing populations. For the industrial revolution in England was followed by the harnessing of coal in France, then in Germany, then later in Japan, and this set in motion among them the processes of imperial expansion, whose friction and clash culminated in the World War. It was as necessary to the success of the industrial revolution, particularly in specialized little England, that the surplus populations which were poured by the million into America should send back food to Europe, as it was that their factory machines should have coal to drive them. This interdependence was not conscious, not a deliberate effort on either side, but it was an extremely practical fact nevertheless. In order that England might live by trade, some other land must live by agriculture, and during the first hundred and fifty years of the industrial revolution that land was America.