Page "History of Russia (1892–1917)" Paragraph 23

After Austria – Hungary's annexation of Bosnia and Herzegovina, Russia became a major part of the increased tension and conflict in the Balkans.

In 1912 Bulgaria, Serbia, Greece, and Montenegro defeated the Ottoman Empire in the First Balkan War, but the putative allies continued to quarrel among themselves.

Then in 1913, the alliance split, and the Serbs, Greeks, and Romanians defeated Bulgaria in the Second Balkan War.

Austria – Hungary became the patron of Bulgaria, which now was Serbia's territorial rival in the region, and Germany remained the Ottoman Empire's protector.

Russia tied itself more closely to Serbia than it had previously.

The complex system of alliances and Great Power support was extremely unstable ; among the Balkan parties harboring resentments over past defeats, the Serbs maintained particular animosity toward the Austro-Hungarian annexation of Bosnia and Herzegovina.