Even before the end of the first world war, during the inter-war years and right up to the outbreak of the second world war, a vein of political thought ran through Europe, which condemned national sovereignties and set up against them the idea of a European federation.
In reality, the federalist trend of thought in the inter-war years remained marginal to the main political currents, and partook more of the nature of prophecy than of politics. In the 1920s and 1930s politics in Europe were both tense and varied, culminating in the emergence of many political-ideological tyrannies. But in spite of the violent divergences over political problems in those years, politics itself, of the right and of the left, of moderates and radicals, of conservatives and revolutionaries, was based on the profound experience which the peoples had lived through during the first world war, namely of the solidity of the nation state. This experience led to the conviction that only on this rock could anything be built.