A cause to fight

Why do individuals participate in civil conflict? Materialist explanations have dominated quantitative scholarship on the causes and conduct of civil wars. Yet, a substantial body of qualitative, historical, and ethnographic evidence suggests that nonmaterial, ideological motives contribute to individuals' decision to enter combat and their battlefield performance. We bridge these two perspectives by developing a model of civil war recruitment where potential fighters trade off ideological and material incentives to enlist. More ideologically committed individuals are (i) more willing to sacrifice income to enlist, (ii) more likely to exert greater effort in combat and accordingly are assigned to riskier tasks, and (iii) less responsive to changes in enlistment costs. Using detailed biographical data on members of the British Battalion of the Republican Army in the Spanish Civil War, we find support for all three implications. Individuals indeed trade off economic and ideological incentives to participate and perform in conflict.