Balkan Wars, 1912-13, two short wars fought on the Balkan Peninsula. In the first war the Ottoman (Turkish) Empire lost its holdings in Europe, except for a small area around Constantinople (Istanbul). In this war, Serbia, Bulgaria, Greece, and Montenegro defeated Turkey. In the second war, Serbia, Greece, Montenegro, Romania, and Turkey defeated Bulgaria in a conflict over conquered Turkish territory.
For nearly 400 years after their capture of Constantinople in 1453, the Ottoman Turks dominated the Balkan Peninsula. However, the Slavic and Greek inhabitants were allowed to practice Christianity and were never assimilated. As the power of the Ottoman Empire declined in the 19th and early 20th centuries, Greece, Serbia, Romania, Montenegro, and Bulgaria each won independence, but the Turks continued to hold a strip of territory extending westward from Constantinople through Thrace, Macedonia, and Albania.
In 1912, a Turkish defeat by Italy encouraged Bulgaria to conclude treaties with Serbia and Greece against Turkey, forming the Balkan League. Montenegro, although not formally a member of the league, joined the alliance and was the first to declare war on Turkey (October 8, 1912). Bulgaria, Greece, and Serbia followed.
The Turks were ill-prepared to defend their European territory. Bulgarian and Serbian victories and the Greek capture of Salonika led to an armistice on December 3, 1912. A peace conference opened in London but negotiations soon broke down, and warfare was resumed in February, 1913.
A second armistice was negotiated in April, 1913, after the Turkish strongholds of Adrianople (Edirne) and Janina (Ioannina) fell. At the reopened London peace conference, Turkey ceded Crete and all its European territory except the Constantinople area. The major European powers insisted on the independence of Albania despite Serbian claims in that area, leaving the division of the rest of the former Ottoman territory to further negotiations.
Serbia, blocked by the major powers from gaining Albania, demanded a greater share of the territory to the south. By June 1, 1913, Serbia and Greece had concluded a treaty with secret provisions for a division of Macedonian territory held by Bulgaria. Meanwhile, Romania had become alarmed over Bulgarian conquests, and Turkey wanted to regain Adrianople. Czar Nicholas II, hoping to gain influence in the Balkans, urged Bulgaria to accept Russian arbitration of the conflicting claims to Macedonia.
However, Bulgarian military leaders, frustrated with the negotiations, were anxious to assert their nation's power. On June 29, 1913, Bulgaria attacked Greek and Serbian military positions in Macedonia. Greece, Serbia, and Romania promptly declared war on Bulgaria, and they were soon followed by Turkey and Montenegro. From the north, the Romanian army moved rapidly on Bulgaria's capital, Sofia, while Bulgaria's armies fought Serbian, Greek, and Turkish forces in the south and west.
Bulgaria sued for peace, and an armistice was arranged on July 30, 1913. By the Treaty of Bucharest, August 10, Bulgaria ceded part of the Dobruja area to Romania, and agreed to split Macedonia with Serbia and Greece. By a later agreement, Adrianople was returned to Turkey. These settlements ended the immediate conflict, but rivalries among the Balkan states over territory remained.