The decisive defeat of an enemy in conventional war—conquest—frequently brings about peace on the victor’s terms; in some cases, however, conquest does not end the violence, but instead marks a transition to guerrilla war. What determines whether conquest results in war termination? While traditional theories of insurgency would predict that peace depends on appealing to the hearts and minds of the defeated population, I argue that conquerors in conventional wars cannot expect to win over the defeated population, and hence that avoiding post-conquest resistance requires quick and often brutal responses to initial opposition to deter potential challengers. I test this argument both statistically and through two sets of short paired case studies.