War with Outsiders Makes Peace Inside

This article presents a new theoretical perspective on the diversionary use of force. Players are partitioned into groups and choose how to allocate their resources to production, fighting against other groups, and fighting internally. The model gives a rationalist explanation of the group cohesion effect: when there is a lot of fighting between groups, there is less internal fighting. In equilibrium, players choose sufficiently high external conflict in order to avoid internal conflict. In contrast with the existing literature, this diversionary use of force takes place even though there is no asymmetric or incomplete information.