If you were to examine an 1816 map of the world, you would discover that half the countries represented there no longer exist. Yet since 1945, the disappearance of individual states from the world stage has become rare. State Death is the first book to systematically examine the reasons why some states die while others survive, and the remarkable decline of state death since the end of World War II. Grappling with what is a core issue of international relations, Tanisha Fazal explores two hundred years of military invasion and occupation, from eighteenth-century Poland to present-day Iraq, to derive conclusions that challenge conventional wisdom about state death. The fate of sovereign states, she reveals, is largely a matter of political geography and changing norms of conquest. Fazal shows how buffer states--those that lie between two rivals--are the most vulnerable and likely to die except in rare cases that constrain the resources or incentives of neighboring states. She argues that the United States has imposed such constraints with its global norm against conquest--an international standard that has largely prevented the violent takeover of states since 1945. State Death serves as a timely reminder that should there be a shift in U.S. power or preferences that erodes the norm against conquest, violent state death may once again become commonplace in international relations.