Unification of Moldavia and Wallachia

The unification of Moldavia and Wallachia (Romanian: Unirea Moldovei și Țării Românești), also known as the unification of the Romanian Principalities (Romanian: Unirea Principatelor Române) or as the Little Union (Romanian: Mica Unire), happened in 1859 following the election of Alexandru Ioan Cuza as prince of both the Principality of Moldavia and the Principality of Wallachia. A potential unification between the two principalities, which shared a common Romanian ethnicity, language, and culture, had not been favored by the great powers for a long time, although it was accepted by them once it happened.

Source: Wikipedia — Unification of Moldavia and Wallachia (CC BY-SA 4.0)