Prince-Bishopric of Montenegro was аn ecclesiastical principality that existed from 1696 until 1852. It emerged from the Serbian Orthodox bishops of Cetinje, later metropolitans, who renounced Ottoman overlordship and transformed the parish of Cetinje to a Russian de facto protectorate, ruling as Metropolitans (vladika, also rendered "Prince-Bishop"). The history starts with Danilo Šćepčević, a bishop of Cetinje who united several clans of Montenegro into fighting the Ottoman Empire that had occupied most of southeastern Europe. Danilo was the first of the House of Petrović-Njegoš to occupy the office as Metropolitan of Cetinje until 1851, when Montenegro became a secular state (principality) under Danilo I Petrović-Njegoš. Also, it became a brief monarchy when it was temporary abolished 1767–1773, when impostor Little Stephen, posed as Russian Emperor and crowned himself Lord of Montenegro.
The Principality of Montenegro (Serbian: Књажевина Црнa Горa/Knjaževina Crna Gora) was a former realm in Southeastern Europe that existed from 13 March 1852 to 28 August 1910. It was then proclaimed a kingdom by Nicholas I, who then became king.
On 28 November 1918 Montenegro was unified with the Kingdom of Serbia, then three days later, on 1 December 1918, it was incorporated into the Kingdom of Serbs, Croats and Slovenes.