The Balkan Wars of 1912-13 represent a milestone in the transformation of Southeastern Europe. From a region managed on the basis of multiculturalism under Ottoman authority, an area of nationalist states emerged. While this process was already well underway before the Balkan Wars, by their completion the process of the nationalization of Southeastern Europe had become assured. This article investigates the demise of the Ottoman system and its aftermath, highlighting the historical roots of still ongoing disputes in the region.