LAUSR

Armed groups are prone to instability and fragmentation, but what explains variation among the new groups that emerge? I argue that the internal politics preceding organizational splits is critical. When it comes to the survival of breakaway groups, those forming around single issue areas gain an advantage by attracting more homogeneous, preference-aligned recruits. On the other hand, those forming over a variety of grievances attract a more heterogeneous population whose divergent views undermine cohesion and cooperation, necessitate hierarchy, and diminish the odds of organizational survival. I test this argument with a case study of two Republican groups from Northern Ireland—the Real Irish Republican Army and the Irish National Liberation Army. The findings confirm my argument and underscore the limited utility of studying organizational fractures from the sole perspective of contemporaneous external events like conciliation and repression. Rather, I show how internal political dynamics influence the composition, identity, and overall trajectory of breakaway groups. This has implications for designing effective counterinsurgent policies, for understanding the formation of armed groups, and for anticipating whether breakaway groups are likely to escalate, moderate, or adopt spoiling behavior.