In Czechoslovak terms, 1918 was a revolution. Before the war the Czechs and Slovaks were kindred peoples in separate sectors of a German and Magyar-ruled state. Germany used the principle to assist its recovery as a power and to undermine Czechoslovakia’s existence. Britain and ultimately France grasped it as a shield for their unwillingness to fulfil their obligations towards Czechoslovakia. As far as the Czechoslovaks were concerned, the international scene after 1918 was not all change. In particular, Czechoslovakia had not lost its strategic importance. The Czech Lands were the fortress heart of Europe. The history of the Czechs and Slovaks after 1918 is thus the history of the independent state of Czechoslovakia and of its struggle to survive in a world that blessed it in principle but was less kind to it in practice. The vagaries of history and the decisions of the peace conference gave Czechoslovakia an ethnically mixed population.