In the early hours of June 17, 1913, the Bulgarian army treacherously attacked its former allies - Serbia and Greece.
After the signing of the London Peace Treaty on May 17, 1913, relations in the victorious coalition became tense.
The treaty ended the war, but did not eliminate the military situation in the Balkans. The reason was the tension that arose between the main players in the victorious coalition.
If a year ago Bulgaria managed to create an effective and successful bloc against the Ottoman Empire through diplomacy, then in the months surrounding the preparation of the peace treaty in London Sofia fell into international isolation.
According to some historians, blinded by military successes, Tsar Ferdinand ordered on June 16, 1913 our army to attack the recent allies Greece and Serbia.
He is impatient to wait for the arbitration of the Russian Tsar. The consequences are deplorable for Bulgaria.
The war begins in the early dawn of June 17, 1913 without warning with unsuccessful offensive actions of the Bulgarian 4th and 2nd armies against the Serbian and Greek armed forces, respectively.
On June 19, the Greek army advances and reaches the valleys of the Struma and Strumeshnitsa rivers. In this way, the rear of the 4th Army is threatened and it is forced to withdraw. Unsuccessful combat operations also led the remaining Bulgarian units in their directions.
On June 29, the Turkish army went on the offensive and, overcoming weak resistance, reached the old state border. The offensive of the Romanian troops began in early July. Without encountering any resistance, the 5th Romanian Corps captured Dobrudzha, and the Danube Army reached the Petrohanski Prohod-Saranci-Zlatitsa-Lovech line. By mid-July, the Greek troops reached Gorna Dzhumaya.
In this situation, the Bulgarian command conducted a counteroffensive between July 14 and July 17. Thus, the main group of the Greek army in the Kresna Gorge was threatened with encirclement. Faced with the looming danger, Greece agreed to an immediate armistice, which was signed and came into force at 1:00 p.m. on July 18.
In the Second Balkan War, Bulgaria lost about 33,000 killed and 60,000 wounded.
On July 28, the Bucharest Peace Treaty of 1913 was signed, according to which Bulgaria was not only deprived to a significant extent of the lands liberated by it during the Balkan War of 1912-1913, but also suffered heavy financial and other losses.