🔎 Question and Theory: Why do individuals join civil wars? Quantitative literature has largely emphasized material incentives, while qualitative, historical, and ethnographic studies point to nonmaterial, ideological motives. A formal model of recruitment is developed in which potential fighters trade off ideological commitment against material payoffs when deciding whether to enlist.

📊 How recruitment was modeled: The model predicts three implications of greater ideological commitment:

• Greater willingness to forgo income to enlist.
• Higher effort in combat, which leads to assignment to riskier tasks.
• Lower responsiveness to changes in enlistment costs.

🧾 Evidence from British Battalion biographies: Detailed biographical data on members of the British Battalion of the Republican Army in the Spanish Civil War are used to test the model’s implications. The dataset links individual backgrounds and choices to battlefield roles and observed behavior.

📌 Key findings:

• Biographical evidence supports all three model implications: more ideologically committed fighters accept lower pay, exert greater effort, and are placed in riskier assignments.
• Ideological commitment reduces sensitivity to enlistment costs, consistent with the model’s prediction about responsiveness.
• Overall, individuals make observable tradeoffs between economic incentives and ideological motives when choosing to participate and when performing in combat.

💡 Why it matters: This work bridges materialist quantitative approaches and qualitative accounts by formally incorporating ideology into a recruitment model and validating its predictions with historical biographical data. The findings show that ideology meaningfully shapes both recruitment decisions and battlefield performance, with implications for studying recruitment, rebel organization, and the dynamics of civil conflict.