Mass media are a key instrument for elites to influence citizens' beliefs and preferences. In this paper, I examine the role that a radio station captured by Franco's army in the first days of the Spanish Civil War played in the number of casualties in territories they controlled during the war. Using a measure of radio signal strength, I estimate the causal effect of radio availability on the number of killings perpetrated by Republican and Francoist forces. In contrast to recent work, I find that access to radio propaganda reduced violence. Specifically, a one standard deviation increase in radio signal strength is associated with a 36% decrease in the number of rebel killings in rebel-controlled territories. The evidence presented suggests that radio demobilized Republicans, which helped Franco consolidate power in areas under his control.