The Serbo-Bulgarian War took place in 1885 between the Kingdom of Serbia and the Principality of Bulgaria. The conflict arose after Bulgaria declared unification with Eastern Rumelia, a region previously under Ottoman control. Serbia opposed this unification, fearing it would increase Bulgaria's power in the Balkans. The war lasted from November 1885 to March 1886 and ended with a Bulgarian victory. The Treaty of Bucharest was signed in 1886, which recognized Bulgaria's unification but did not significantly alter territorial boundaries. The war had lasting effects on Balkan politics and set the stage for future conflicts in the region.