This paper studies the effect of strengthening democracy, as captured by an increase in voting rights, on the incidence of violent civil conflict in nineteenth-century Colombia. Empirically studying the relationship between democracy and conflict is challenging, not only because of conceptual problems in de ning and measuring democracy, but also because political institutions and violence are jointly determined. We take advantage of an experiment of history to examine the impact of one simple, measurable dimension of democracy (the size of the franchise) on conflict, while at the same time attempting to overcome the identi cation problem. In 1853, Colombia established universal male sufferage. Using a simple difference-indifferences specification at the municipal level, we find that municipalities where more voters were enfranchised relative to their population experienced fewer violent political battles while the reform was in effect. The results are robust to including a number of additional controls. Moreover, we investigate the potential mechanisms driving the results. In particular, we look at which components of the proportion of new voters in 1853 explain the results, and we examine if results are stronger in places with more political competition and state capacity. We interpret our findings as suggesting that violence in nineteenth-century Colombia was a technology for political elites to compete for the rents from power, and that democracy constituted an alternative way to compete which substituted violence.