In 1859, Alexander Ioan Cuza was elected prince of two vassal states of the Ottoman Empire – Moldavia and Wallachia. The two formally united in 1862, becoming The Romanian United Principalities. Alexander ruled as Domnitor (Prince) Alexandru Ioan I until he was forced to abdicate in 1866.

The Romanian parliament, under the advice of Napoleon and the Prussians, offered to the throne to Prince Karl of Hohenzollern-Sigmaringen. Under a new constitution established just after Karl’s arrival, he ruled the newly named Romania as Prince Carol I, Domnitor of Romania. Some years later, Romania declared total independence from the Ottoman Empire which was recognized by the Treaty of Berlin in 1878, and in 1881 became a Kingdom, with Carol becoming the first King of Romania.

The House of Hohenzollern-Sigmaringen would rule Romania for another 66 years until King Michael was forced to abdicate in 1947.

Principality of Romania
1862-1866    Prince Alexander Ioan I, Domnitor of Romania
1866-1881    Prince Carol I, Domnitor of Romania

Kingdom of Romania
1881-1914    King Carol I
1914-1927    King Ferdinand I
1927-1930    King Michael I
1930-1940    King Carol II
1940-1947    King Michael I (monarchy abolished)