The Principality of Bulgaria was a vassal state under the suzerainty of the Ottoman Empire. It was established by the Treaty of Berlin in 1878.
Stefan Stambolov
An IMARO banner
Administrative subdivisions of Eastern Rumelia in 1907
Bulgarian unification of 1885
Russo-Turkish War (1877–1878)
The Russo-Turkish War was a conflict between the Ottoman Empire and a coalition led by the Russian Empire which included Bulgaria, Romania, Serbia, and Montenegro. Fought in the Balkans and in the Caucasus, it originated in emerging 19th-century Balkan nationalism. Additional factors included the Russian goals of recovering territorial losses endured during the Crimean War of 1853–1856, re-establishing itself in the Black Sea and supporting the political movement attempting to free Balkan nations from the Ottoman Empire.
Clockwise, from top left: the Action off Măcin, the Battle of Shipka Pass, the Battle of Tashkessen, the Siege of Plevna
The Moni Arkadiou monastery
Ottoman Empire in 1862
Herzegovinian insurgents in 1875