Union of Transylvania with Romania

The Union of Transylvania with Romania was declared on December 1 [O.S. November 18] 1918 by the assembly of the delegates of ethnic Romanians held in Alba Iulia.

The national holiday of Romania, the Great Union Day (also called Unification Day) occurring on December 1, celebrates this event. The holiday was established after the Romanian Revolution, and marks the unification not only of Transylvania, but also of the provinces of Banat, Bessarabia and Bukovina with the Romanian Kingdom. These other provinces had all joined with the Kingdom of Romania earlier in 1918, and the Union of Transylvania with Romania thus resulted in the final unification of the entire country.

On December 1, 1918 (November 18 Old Style), the National Assembly of Romanians of Transylvania and Hungary, consisting of 1,228 elected representatives of the Romanians in Transylvania, Banat, Crişana and Maramureş, convened in Alba Iulia and decreed (by unanimous vote)

The Resolution voted by the National Assembly stipulated also the "fundamental principles for the foundation of the new Romanian State":

The union was conditional, and demanded the preservation of a democratic local autonomy, the equality of all nationalities and religions.

The Assembly also formed from 200 of its members, plus 50 co-opted members a High National Romanian Council of Transylvania, the new permanent parliament of Transylvania.

The next day, on December 2, 1918 the High National Romanian Council of Transylvania formed a government under the name of Directory Council of Transylvania (Consiliul Dirigent al Transilvaniei), headed by Iuliu Maniu.

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Wikipedia