The Balkan Wars of 1912–13

The Balkan Wars show how rival nationalisms could unite against a common enemy and then turn on each other. In 1912 Serbia, Bulgaria, Greece and Montenegro formed the Balkan League, encouraged by Russia, and attacked the Ottoman Empire in October. Within weeks they had driven Ottoman forces from most of Europe, and Albania declared independence in November 1912.

The Treaty of London in May 1913 confirmed Ottoman losses, but the victors disagreed over dividing Macedonia, a region of mixed Bulgarian, Greek, Serbian, Albanian and Turkish populations claimed by several states. In June 1913 Bulgaria attacked its former allies and was defeated by Serbia, Greece, Romania and the Ottomans in the Second Balkan War.

The Treaty of Bucharest in August 1913 left Bulgaria resentful, Serbia enlarged and confident, and Austria-Hungary alarmed by Serbian power. Civilians suffered heavily, many were displaced, and the wars made the Balkans, in a phrase of the time, a powder keg.