The Balkan Wars of 1912–1913 were two closely connected conflicts that reshaped southeastern Europe and increased tensions before the First World War. In the First Balkan War (1912–1913), the Balkan League, consisting of Serbia, Bulgaria, Greece, and Montenegro, united against the weakening Ottoman Empire. Their aim was to drive the Ottomans from their remaining European territories. The League achieved rapid military success, forcing the Ottoman Empire to surrender most of its European possessions under the Treaty of London in May 1913.

However, disagreements soon emerged over the division of the conquered lands, particularly Macedonia. In June 1913, Bulgaria attacked its former allies, Serbia and Greece, beginning the Second Balkan War. Romania and the Ottoman Empire also entered the conflict against Bulgaria. Bulgaria was quickly defeated and forced to sign the Treaty of Bucharest in August 1913, losing much of the territory it had hoped to gain.

The Balkan Wars significantly altered the political map of the region. Serbia emerged stronger and more influential, alarming Austria-Hungary, while Bulgaria felt deeply resentful over its losses. These rivalries and nationalist tensions contributed to the unstable political climate that ultimately led to the outbreak of the First World War in 1914 following the assassination of Archduke Franz Ferdinand.