Second Balkan War

The Second Balkan War was a conflict which broke out when Bulgaria, dissatisfied with its share of the spoils of the First Balkan War, attacked its former allies, Serbia and Greece, on 16 ( O.S.) / 29 (N.S.) June 1913. Serbian and Greek armies repulsed the Bulgarian offensive and counter-attacked, entering Bulgaria. With Bulgaria also having previously engaged in territorial disputes with Romania and the bulk of Bulgarian forces engaged in the south, the prospect of an easy victory incited Romanian intervention against Bulgaria. The Ottoman Empire also took advantage of the situation to regain some lost territories from the previous war. When Romanian troops approached the capital Sofia, Bulgaria asked for an armistice, resulting in the Treaty of Bucharest, in which Bulgaria had to cede portions of its First Balkan War gains to Serbia, Greece and Romania. In the Treaty of Constantinople, it lost Adrianople to the Ottomans.

The political developments and military preparations for the Second Balkan War attracted an estimated 200 to 300 war correspondents from around the world.

Background

During the First Balkan War, the Balkan League (Bulgaria, Serbia, Montenegro and Greece) succeeded in driving out the Ottoman Empire from its European provinces (Albania, Macedonia, Sandžak and Thrace), leaving the Ottomans with only East Thrace. The Treaty of London, signed on 30 May 1913, which ended the war, acknowledged the Balkan states' gains west of the Enos–Midia line, drawn from Midia (Kıyıköy) on the Black Sea coast to Enos (Enez) on the Aegean Sea coast, on an ''uti possidetis'' basis, and created an independent Albania.

However, the relations between the victorious Balkan allies quickly soured over the division of the spoils, especially in Macedonia. During the pre-war negotiations that had resulted in the establishment of the Balkan League, Serbia and Bulgaria signed a secret agreement on 13 March 1912 which determined their future boundaries, in effect sharing northern Macedonia between them. In case of a postwar disagreement, the area to the north of the Kriva Palanka–Ohrid line (with both cities going to the Bulgarians), had been designated as a "disputed zone" under Russian arbitration and the area to the south of this line had been assigned to Bulgaria. During the war, the Serbs succeeded in capturing an area far south of the agreed border, down to the Bitola–Gevgelija line (both in Serbian hands). At the same time, the Greeks advanced north, occupying Thessaloniki shortly before the Bulgarians arrived, and establishing a common Greek border with Serbia.

When Bulgarian delegates in London bluntly warned the Serbs that they must not expect Bulgarian support on their Adriatic claims, the Serbs angrily replied that that was a clear withdrawal from the prewar agreement of mutual understanding according to the Kriva Palanka-Adriatic line of expansion, but the Bulgarians insisted that in their view, the Vardar Macedonian part of the agreement remained active and the Serbs were still obliged to surrender the area as agreed. The Serbs answered by accusing the Bulgarians of maximalism, pointing out that if they lost both northern Albania and Vardar Macedonia, their participation in the common war would have been virtually for nothing.

When Bulgaria called upon Serbia to honor the pre-war agreement over northern Macedonia, the Serbs, displeased at the Great Powers' requiring them to give up their gains in northern Albania, adamantly refused to evacuate any more territory. The developments essentially ended the Serbo-Bulgarian alliance and made a future war between the two countries inevitable. Soon thereafter, minor clashes broke out along the borders of the occupation zones with the Bulgarians against the Serbs and the Greeks. Responding to the perceived Bulgarian threat, Serbia started negotiations with Greece, which also had reasons to be concerned about Bulgarian intentions.

On 19 May/1 June 1913, two days after the signing of the Treaty of London and just 28 days before the Bulgarian attack, Greece and Serbia signed a secret defensive alliance