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.