That military intervention seriously affects inter-ethnic relations in multi-ethnic states may seem a trivial observation. Nevertheless, how and why this happens remains surprisingly understudied. The purpose of this project is to systematically examine the factors that shape the consequences of military intervention for inter-ethnic relations in post-conflict societies. This will be achieved through analysis of four case studies. Particular emphasis is placed on nation-building – understood as attempts at and/or the process of (re)building a sense of oneness within the population of a state – and its specific role in building a sustainable peace. The four cases are Kosovo, East Timor, Afghanistan and Abkhazia.