Personal union of the Principality of Wallachia and Principality of Moldavia under Alexandru Ioan Cuza from 1859, formally merged into a single state (Romania) by 1862; continued under Carol I (Domnitor) after Cuza's 1866 overthrow until Romania's international independence was recognized (1878 Congress of Berlin) and Carol was crowned king in 1881.
Transformed into the Kingdom of Romania on 14 March / 10 May 1881 when Carol I was crowned king.
Cambridge's standard one-volume history covering the union of the principalities, the kingdom, and the socialist republic.