"Nation states were a comparative novelty in European history. Much of the continent in 1900 was still dominated by the long-established and ethnically mixed empires of the Habsburgs, Romanovs and Osmanli. The United Kingdom of Great Britain and Ireland was another such entity. Some smaller countries were also ethnically heterogeneous: Belgium and Switzerland, for example. And there were numerous petty principalities and grand duchies, like Luxembourg or Lichtenstein, that had no distinct national identity of their own, yet resisted absorption into bigger political units. These patchwork political structures made practical sense at a time when mass migration was increasing rather than reducing ethnic intermingling. Yet in the eyes of political nationalists, they deserved to be consigned to the past; the future should belong to homogeneous nation states. France, which had nurtured in the Swiss political philosopher Jean-Jacques Rousseau the prophet of popular sovereignty, also provided a kind of model for nation-building. A republic forged and re-forged in repeated revolutions and wars, France by 1900 seemed to have subsumed all its old regional identities in a single 'idea of France'. Auvergnais, Bretons and Gascons alike all considered themselves to be Frenchmen, having been put through the same standardized schooling and military training."