Throughout the history of the modern world, domestic regime change- be it democratization, autocratization, decolonization, decommunization, federal dissolution, coups, or revolutions- has often triggered international conflict and war. When a regime changes, decaying institutions from the ancien regime compete with new rules of the game to shape political competition in ambiguous ways. This uncertain text provides opportunities for political actors, both old and new, to pursue new strategies for achieving their objectives, including belligerent policies against both domestic and international foes. In desperation, losers from regime change may resort to violence to maintain their former privileges. Such internal conflicts become international wars when these interest groups who benefited from the old order call upon their allies to intervene on their behalf or strike out against their enemies as means to shore up their domestic legitimacy. In the name of democracy, independence, the revolution, or the nation, the beneficiaries of regime change also can resort to violence against both domestic and international opponents to secure their new gains.