Comrades and Cause: Peer Influence on West Point Cadets' Civil War Allegiances

2025-07-12

AI Summary

Can social networks influence high-stakes life decisions under conditions of extreme political polarization? This paper examines peer effects on loyalty choices among U.S. Military Academy (West Point) cadets during the Civil War era. Employing a quasi-natural experimental design, we leverage exogenous variation in the share of cadets from free states across graduating classes to identify causal effects, complemented by archival analysis of long-term career outcomes. Results show that cadets from slaveholding states were significantly more likely to join the Union Army when their cohort contained a higher proportion of peers from free states. This peer-induced choice not only demonstrates the potency of social influence but also generated persistent positive effects on subsequent rank advancement and military career trajectories. The study extends social influence theory to contexts of acute political fragmentation and provides the first empirical, causal evidence of peer network effects on historically consequential, high-cost decisions.

Technology Category

• Game Theory and Economic Paradigms: Social Choice / Voting
• Reasoning under Uncertainty: Causality
• Cognitive Modeling & Cognitive Systems: Social Cognition And Interaction

Application Category

• Social Networks and Social Media: Influence propagation, information diffusion, and the prediction on networks
• Economics, Online Markets and Human Computation: Social networks and social learning
• User Modeling, Personalization and Recommendation: Social recommender systems and personalization for the social Web

Abstract

Do social networks and peer influence shape major life decisions in highly polarized settings? We explore this question by examining how peers influenced the allegiances of West Point cadets during the American Civil War. Leveraging quasi-random variations in the proportion of cadets from Free States, we analyze how these differences affected decisions about which army to join. We find that a higher proportion of classmates from Free States significantly increased the likelihood that cadets from Slave States joined the Union Army, while almost all cadets from Free States joined the Union Army (if they decided to join the war). We further examine how cadets' decisions affected their military rank and career outcomes. Our findings highlight that peers still influence choices even when they are life-altering and occur during periods of extreme polarization.

Problem

• How peer influence affects cadets' Civil War allegiances
• Impact of Free State peers on Slave State cadets' decisions
• Peer effects on military career outcomes in polarized settings

Innovation

• Quasi-random variations in peer demographics
• Analyzing peer influence on army allegiance
• Examining military rank and career outcomes