The Balkan Wars were two wars in South-eastern Europe in 1912-1913 in the course of which the Balkan League (Bulgaria, Montenegro, Greece, and Serbia) first conquered Ottoman-held Macedonia and most of Thrace and then fell out over the division of the spoils.

The background to the wars lies in the incomplete emergence of nation-states on the fringes of the Ottoman Empire during the nineteenth century. Serbians had gained substantial territory during the Russo-Turkish War, 1877-78, while Greece acquired Thessaly in 1881 (although it lost a small area to the Ottoman Empire in 1897) and Bulgaria (an autonomous principality since 1878) incorporated the formerly distinct province of Eastern Rumelia (1885). All three as well as tiny Montenegro sought additional territories within the large Ottoman-ruled regions known as Roumelia, comprising Eastern Roumelia, Albania, Macedonia, and Thrace (see map).