The union of Bessarabia with Romania was proclaimed on April 9 [O.S. March 27] 1918 by Sfatul rii, the legislative body of the Moldavian Democratic Republic. This state had the same borders of the region of Bessarabia, which was annexed by the Russian Empire following the Treaty of Bucharest of 1812 and organized first as an Oblast (autonomous until 1828) and later as a Governorate. Under Russian rule, many of the native Tatars were expelled from parts of Bessarabia and replaced with Moldavians, Wallachians, Bulgarians, Ukrainians, Greeks, Russians, Lipovans, Cossacks, Gagauzes and other peoples, although colonization was not limited to formerly Tatar-inhabited lands. Russia also tried to integrate the region by imposing the Russian language in administration and restricting education in other languages.

The beginning of World War I caused an increase in national awareness among the Bessarabians, and, following the beginning of the Russian Revolution in 1917, Bessarabia proclaimed its own parliament, the Sfatul rii, which declared the Moldavian Democratic Republic. Following a Romanian military intervention, with the Romanian Army firmly in control of the region, the Sfatul rii voted for independence and proclaimed on April 9 [O.S. March 27] 1918 unification with the Kingdom of Romania. Although the unification was made under various conditions, all of these except the promise of an agrarian reform, which was carried out, were later abandoned by a minority of the Sfatul. Later, the Romanian administration swiftly dissolved the assembly and rejected the protests of the former deputies. In the peace talks after World War I, the European powers awarded Bessarabia to Romania, although the newly formed Russian SSR, supported by the United States, never recognized this.

However, the situation in Bessarabia would change after the signing of the MolotovRibbentrop Pact between the Soviet Union (USSR) and Nazi Germany, in which the latter expressed its disinterest in the region. This allowed the USSR to send an ultimatum to Romania, which was now diplomatically isolated with the outbreak of World War II, on 26 June 1940 in which it demanded Bessarabia and also Northern Bukovina. After Romania accepted it, the USSR occupied these territories, ending Romanian rule in the zone. Bessarabia was organized and split between the Ukrainian SSR and the new Moldavian SSR, which gained independence in 1991 as Moldova. Ever since, there has been a minority but growing movement to reunite the region with Romania, with supporters in Romania and Moldova commemorating the day of the union, 27 March, on the Day of the Union of Bessarabia with Romania.



Bessarabia (; Gagauz: Besarabiya; Romanian: Basarabia; Russian: Бессарабия, Bessarabiya; Turkish: Besarabya; Ukrainian: Бессара́бія, Bessarabiya; Bulgarian: Бесарабия, Besarabiya) is a historical region in Eastern Europe, bounded by the Dniester river on the east and the Prut river on the west. About two thirds of Bessarabia lies within modern-day Moldova, with the Ukrainian Budjak region covering the southern coastal region and part of the Ukrainian Chernivtsi Oblast covering a small area in the north.

In the aftermath of the Russo-Turkish War (1806–1812), and the ensuing Peace of Bucharest, the eastern parts of the Principality of Moldavia, an Ottoman vassal, along with some areas formerly under direct Ottoman rule, were ceded to Imperial Russia. The acquisition was among the Empire's last territorial acquisitions in Europe. The newly acquired territories were organised as the Bessarabia Governorate of the Russian Empire, adopting a name previously used for the southern plains between the Dniester and the Danube rivers. Following the Crimean War, in 1856, the southern areas of Bessarabia were returned to Moldavian rule; Russian rule was restored over the whole of the region in 1878, when Romania, the result of Moldavia's union with Wallachia, was pressured into exchanging those territories for the Dobruja.

In 1917, in the wake of the Russian Revolution, the area constituted itself as the Moldavian Democratic Republic, an autonomous republic part of a proposed federative Russian state. Bolshevik agitation in late 1917 and early 1918 resulted in the intervention of the Romanian Army, ostensibly to pacify the region. Soon after, the parliamentary assembly declared independence, and then union with the Kingdom of Romania. However, the legality of these acts was disputed, most prominently by the Soviet Union, which regarded the area as a territory occupied by Romania.

In 1940, after securing the assent of Nazi Germany through the Molotov–Ribbentrop Pact, the Soviet Union pressured Romania, under threat of war, into withdrawing from Bessarabia, allowing the Red Army to enter and the Soviet Union to annex the region. The area was formally integrated into the Soviet Union: the core joined parts of the Moldavian ASSR to form the Moldavian SSR, while territories inhabited by Slavic majorities in the north and the south of Bessarabia were transferred to the Ukrainian SSR. Axis-aligned Romania recaptured the region in 1941 with the success of Operation München during the Nazi invasion of the Soviet Union, but lost it in 1944 as the tide of war turned. In 1947, the Soviet-Romanian border along the Prut was internationally recognised by the Paris Treaty that ended World War II.

During the process of the dissolution of the Soviet Union, the Moldavian and Ukrainian SSRs proclaimed their independence in 1991, becoming the modern states of Moldova and Ukraine while preserving the existing partition of Bessarabia. Following a short war in the early 1990s, the Pridnestrovian Moldavian Republic was proclaimed in the Transnistria, extending its authority also over the municipality of Bender on the right bank of Dniester river. Part of the Gagauz-inhabited areas in southern Bessarabia was organised in 1994 as an autonomous region within Moldova.