First Balkan War: The 1912 conflict against the Ottoman Empire

The First Balkan War commenced in October 1912, marking a significant conflict between the Balkan League—comprising Bulgaria, Serbia, Greece, and Montenegro—and the Ottoman Empire. The hostilities began following Montenegro's declaration of war and subsequent attacks on Ottoman forces near Skadar.

Driven by demands for administrative reforms in European territories and responses to local violence, the Balkan allies mobilized a combined force of approximately 645,000 troops. The Ottoman Empire, fielding roughly 420,000 soldiers, was ultimately defeated. The conflict concluded with the London Peace Treaty in 1913, which forced the Ottoman Empire to cede most of its European territories west of the Midia-Enos line.

The aftermath of the war led to significant geopolitical shifts. The subsequent division of Macedonia among the victors caused friction, contributing to the outbreak of the Second Balkan War in 1913. These regional instabilities and the rise of Serbia as a regional power are noted as indirect factors that eventually contributed to the onset of World War I.