The most widely used theoretical framework in international relations is realism. Realism takes many forms, and there have been hundreds of writings on the topic. In the United States, the two most popular exemplars of realism are Morgenthau (Morgenthau & Thompson, 1985; original 1948) and Waltz (1979). There is no systematic attempt to incorporate civil wars into the realist framework. In this paper, we use a computer simulation to explore the impact of a state's civil war experience on its interstate war experience. The results suggest that a state's civil war experience can have an impact on its interstate war experience.