Bulgaria Launches Attacks Triggering Second Balkan War

Context

After the Balkan League—comprising Bulgaria, Serbia, Greece, and Montenegro—defeated the Ottoman Empire in the First Balkan War of 1912–1913, the victors faced the difficult task of partitioning the conquered European territories. The Treaty of London in May 1913 had formally ended the war with the Ottomans but left the division of spoils, especially in the contested region of Macedonia, unresolved among the allies themselves. Bulgaria, which had contributed the largest forces and suffered the heaviest casualties, believed it had been shortchanged in the preliminary arrangements, particularly as Serbia and Greece consolidated control over areas Bulgaria viewed as rightfully its own.

What Happened

On the night of June 29–30, 1913, Bulgarian troops under orders from Tsar Ferdinand I opened fire on Serbian positions near the town of Štip in Macedonia without a formal declaration of war. The Bulgarian 4th Army struck Serbian 1st and 3rd Armies, while additional forces engaged Greek units farther south. The surprise attacks initially gained ground, but Serbian and Greek defenders quickly stabilized their lines and began coordinated counteroffensives. Ferdinand had acted largely on his own initiative, bypassing much of his government, in hopes of forcing a favorable renegotiation of the territorial map.

Aftermath

The Bulgarian offensive collapsed within days as Serbian and Greek forces pushed back and advanced into Bulgarian-held territory. Romania mobilized and invaded from the north, while the Ottoman Empire seized the opportunity to reoccupy parts of Thrace it had lost the previous year. By early August, Bulgarian armies were in retreat on multiple fronts, prompting an armistice request. The conflict ended with the Treaty of Bucharest on August 10, 1913, which stripped Bulgaria of most of its recent gains.

Legacy

The Second Balkan War intensified ethnic rivalries and border disputes across the region that would persist for decades. It demonstrated the instability of ad hoc alliances formed solely for territorial gain and left Bulgaria weakened and resentful, factors that influenced its alignments during the First World War. Historians often cite the rapid reversal of Balkan League partnerships as a stark illustration of how local ambitions contributed to the broader European crisis of 1914.