Why did the nation-state emerge and proliferate across the globe? How is this process related to the wars fought in the modern era? Analyzing datasets that cover the entire world over long stretches of time, Andreas Wimmer focuses on changing configurations of power and legitimacy to answer these questions. The nationalist ideal of self-rule gradually diffused over the world and delegitimized empire after empire. Nationalists created nation-states wherever the power configuration favored them, often at the end of prolonged wars of secession. The elites of many of these new states were...