Democracies are less likely to fight wars with each other. They are also more likely to prevail in wars with autocratic states. I offer an explanation of this syndrome of powerful pacifism drawn from the microeconomic theory of the state. State rent seeking creates an imperialist bias in a country's foreign policy. This bias is smallest in democracies, where the costs to society of controlling the state are relatively low, and greatest in autocracies, where the costs are higher. As a result of this bias, autocracies will be more expansionist and, in turn, war-prone. In their relations with each other, where the absence of this imperialist bias is manifest, the relative pacifism of democracies appears. In addition, democracies, constrained by their societies from earning rents, will devote greater absolute resources to security, enjoy greater societal support for their policies, and tend to form overwhelming countercoalitions against expansionist autocracies. It follows that democracies will be more likely to win wars.