The
Balkan League was an alliance formed by a series of bilateral treaties concluded in 1912 between the Balkan states of
Greece,
Bulgaria,
Serbia and
Montenegro, and directed against the
Ottoman Empire, which at the time still controlled much of the Balkan peninsula. The Balkans had been in a state of turmoil since the early 1900s, with years of
guerrilla warfare in Macedonia followed by the
Young Turk Revolution and the protracted
Bosnian Crisis. The outbreak of the
Italo-Turkish War in 1911 had further weakened the Ottomans and emboldened the Balkan states. Under
Russian influence,
Serbia and
Bulgaria settled their differences and signed an alliance, originally directed against
Austria-Hungary on 13 March 1912, but by adding a secret chapter to it essentially redirected the alliance against the
Ottoman Empire. Serbia then signed a mutual alliance with
Montenegro, while Bulgaria did the same with
Greece. The League was victorious in the
First Balkan War which broke out in October 1912, where it successfully wrestled control of almost all European Ottoman territories. Following this victory however, the old differences between the allies re-emerged over the division of the spoils, particularly
Macedonia, leading to the effective break-up of the League, and soon after, on 16 June 1913, Bulgaria attacked her erstwhile allies, beginning the
Second Balkan War.