This paper explores the conditions under which citizens are mobilized for armed insurgency against democratic institutions. Our idea is that pre-conflict social and patronage networks play a crucial role in civilians' mobilization into militias, and that their influences can vary across different phases of the conflict, substituting or complementing coercion carried out with the capacity of the state. We investigate the drivers of fascist mobilization with extensive archival data from the Spanish Civil War in Navarre, a rural province pivotal for the 1936 pro-Franco insurgency. First, with municipal-level data, we show that electoral mobilization by conservative forces in the last, polarized democratic election held in 1936 predicts voluntary conscription in paramilitary militias in the early weeks of the war, when mobilization was left to the initiative of local elites. However, this pattern does not positively predict military recruitment in posterior, draft-based waves of mobilization, which coercively induced compliance in Republican-leaning areas. To observe the drivers of compliance at the individual level, we digitized the pre-war census of Navarre and matched it to records of pro-Franco combatants. Following the literature on electoral clientelism, we estimate pre-war family and occupational network ties between residents in rural villages using surnames and occupational information. Our individual-level findings indicate that network proximity to early promoters of the insurgency enhanced compliance with draft-based conscription among initial non-volunteers in left-wing communities. This study deepens our understanding of the social factors influencing civilians' decision to engage in conflict and their interaction with ideology and threat of retribution.