The extent to which “war makes states” varies depending on whether the experience is offensive or defensive in nature. Offensive wars encourage elite collective action by offering clear selective benefits. Based on their contributions, a defined set of elites can be promised cuts from the spoils of war. Moreover, the expected outcomes of war are relatively predictable, since an attacker can prepare to fight against a specific target. By contrast, defensive warfare could not generate collective action. First, it is hard to exclude non-contributing elites from the benefits of defensive warfare. Second, due to the large variability in potential enemies’ military capacities and tactics, it is difficult to assign responsibility for the outcomes of a defensive conflict. Finally, both the collective and selective benefits are heavily discounted, because it is uncertain when – if ever – an enemy will invade. To overcome the challenges of empirically assessing the effects of an offensive war, I will triangulate three empirical methods. First, I will use difference-in-difference models to compare the effects of military victory for attackers and defenders in the inter-state wars of 19th century Latin America. In addition, I will use historical case studies to evaluate the proposed causal mechanisms. Finally, I will test the theoretical argument in a lab experiment, where I can randomly assign groups to experience offensive or defensive conflicts with one another. The presentation will primarily discuss the pre-analysis plan for this lab experiment.