Governments are likely to be held accountable for the success or failure of their foreign policies. Consequently, we claim that international wars can, under specified conditions, have domestically instigated consequences for violent regime change in the political systems of the participants. Drawing upon all international war participation between 1816 and 1975, we seek to answer the question, Do wars lead to violent changes of regime and if so, under what conditions? Three hypotheses set out the expected associations of a nation's initiator or target role in a war, the war outcome, and the costs of the war with domestically instigated violent changes of regime. Direct relationships are found for all three and hold even against possible threats to their validity and robustness. The results suggest that domestic politics play a larger role in national security policy than is generally believed by realist or neorealist theorists.