December 1 is the celebration of the 1918 „Great Union” of the provinces of Transylvania, Banat, Crișana, Maramureș, Bessarabia, and Bucovina, where ethnic, Romanian-speaking Romanians represented the majority of the population, with the Kingdom of Romania, made up at the time from Wallachia and Moldavia.
The celebration references a series of proclamations and declarations that took place that year, building up to the provinces’ unification, and the December 1, 1918, Alba Iulia proclamation, by which Transylvania, Banat, Crișana, and Maramureș united with the Romanian Kingdom.
The first province to proclaim its union with the kingdom was Bessarabia on March 27, 1918. The province had declared its autonomy and, later, independence after the Russian Revolution of 1917, and, in the spring of 1918, the country’s council voted for unification with the Kingdom of Romania. Bessarabia’s union with Romania lasted for 22 years, until June 28, 1940, when Romania ceded the territory to the Soviet Union.
Bucovina followed on November 28. As the Austro-Hungarian Empire disintegrated after the end of the First World War, the province elected in a National Council at a large, national gathering organized at Cernăuți. By the end of November, a motion declaring the union of Bucovina with Romania was adopted and presented to the Romanian government in Iași.
A few days later, on December 1, the Great National Assembly of Alba Iulia was held, and a resolution concerning the union of Transylvania, Banat, Crișana, and Maramureș with Romania was adopted. King Ferdinand received the Alba Iulia union declaration on December 11, and, on the same day, validated the decree approving the union, including that with Bessarabia with Bucovina.
The international recognition of the union was completed through various international treaties, such as the Treaty of Saint-Germain-en-Laye (1919),