On November 14 (November 2 - old style) 1885, the Serbian King Milan declared war on Bulgaria, and the reason was the Unification between Eastern Rumelia and the Principality of Bulgaria.
The unification radically changed the balance of power on the Balkan Peninsula and caused a reaction from all neighboring countries. Serbia was not happy because its territory remained smaller. Therefore, on September 27 of the same year, it sent its military units to Tran. They crossed the border, but were repelled by the Bulgarian army.
Romania also declared that it would seek expansion into Southern Dobrudja. Greece immediately mobilized and threatened to invade Turkish territory in order to annex parts of Macedonia as compensation.
The international community was also attracted by what was happening in the Balkans. Great Britain supported the Unification because it saw a chance to gain positions in the enlarged Principality and at the same time to shake up Russian positions in the Balkans. Russia, Austria-Hungary, Germany, France and Italy reacted negatively to what had happened in Bulgaria and demanded the restoration of the status quo from before September 6, 1885.
As a first sign of disapproval, Russia immediately recalled all its officers from the principality and ordered the Minister of War in Petko Karavelov's government, Mikhail Kantakuzin, who was also a Russian officer - to resign.
An incredible diplomatic game began, explains Stefan Shivachev, director of the Regional History Museum in Plovdiv. Meanwhile, the Bulgarian army was left without a command staff.
The government of Petko Karavelov from the very beginning of the events clearly recognized the looming danger and tried to stop the impending war by diplomatic means. Negotiations were held in Petersburg, Paris and London. In addition, Sultan Abdul Hamid II also informed the Great Powers about what was happening in the Balkans. They advised him to react calmly and not to take extreme actions.
When Serbia attacked Bulgaria, the Bulgarian prince Alexander II wrote a letter to the sultan. As the head of a vassal state, he was obliged to inform him about the attack from Serbia. And according to the Treaty of Berlin, the Ottoman Empire, as a suzerain, was obliged to defend Bulgaria even by sending its army to the war.
"And suddenly we see that if these small rules are followed, the Ottoman Empire must send troops to defeat the Serbian army. And the Serbian army at the same time was fighting in favor of the Ottoman Empire. There is no doubt that in this situation the Porte began to think, and it thought slowly," Assoc. Prof. Valeri Kolev from the Faculty of History of Sofia University "Kliment Ohridski" told Bulgaria ON AIR.
"On November 9, when the Bulgarian army had launched a counteroffensive, the Sultan suddenly remembered that he had to shake the finger at Serbia and sent a note to King Milan that he would not allow the Bulgarian border to be violated. This was at a time when the Serbs had almost left Bulgarian territory," explains Prof. Todor Petrov from the National Museum of Military History.
On November 16, Prince Alexander I was forced to cease hostilities and stop the impetuous victorious march on Serbian territory. The war ended with a victory for the Bulgarian army. The balance sheet is - 550 Bulgarian soldiers and officers were killed and 700 Serbian. Over 8,000 people were wounded on both sides. The old borders were restored, but the Union of the Principality and Eastern Rumelia received international recognition. The peace treaty between Bulgaria and Serbia was concluded on February 19, 1886 in Bucharest.