The monarchs of Bulgaria ruled the country during three periods of Bulgaria's history as an independent country: from the establishment of the First Bulgarian Empire in 681 to the Byzantine conquest of Bulgaria in 1018; from the Uprising of Asen and Peter that established the Second Bulgarian Empire in 1185 to the annexation of the rump Bulgarian state into the Ottoman Empire in 1396; and from the re-establishment of an independent Bulgaria in 1878 to the abolition of monarchy in a referendum held on 15 September 1946.