Question: When did the country Daugavpils Municipality is located in become part of the Soviet Union?

full_context: Document 1: Latvian Soviet Socialist Republic: Following the Welles Declaration of July 23, 1940, the annexation of Latvia into the Soviet Union (USSR) on 5 August 1940 was not recognized as legitimate by the United States, the European Community, and recognition of it as the nominal fifteenth constituent republic of the USSR was withheld for five decades. Its territory was subsequently conquered by Nazi Germany in June -- July 1941, before being retaken by the Soviets in 1944 -- 1945. Nevertheless, Latvia continued to exist as a de jure independent country with a number of countries continued to recognize Latvian diplomats and consuls who still functioned in the name of their former governments.
Document 2: Estonia: In 1989, during the "Singing Revolution", in a landmark demonstration for more independence, more than two million people formed a human chain stretching through Lithuania, Latvia and Estonia, called the Baltic Way. All three nations had similar experiences of occupation and similar aspirations for regaining independence. The Estonian Sovereignty Declaration was issued on 16 November 1988. On 20 August 1991, Estonia declared formal independence during the Soviet military coup attempt in Moscow, reconstituting the pre-1940 state. The Soviet Union recognised the independence of Estonia on 6 September 1991. The first country to diplomatically recognise Estonia's reclaimed independence was Iceland. The last units of the Russian army left on 31 August 1994.
Document 3: Warsaw: The basic unit of territorial division in Poland is a commune (gmina). A city is also a commune – but with the city charter. Both cities and communes are governed by a mayor – but in the communes the mayor is vogt (wójt in Polish), however in the cities – burmistrz. Some bigger cities obtain the entitlements, i.e. tasks and privileges, which are possessed by the units of the second level of the territorial division – counties or powiats. An example of such entitlement is a car registration: a gmina cannot register cars, this is a powiat's task (i.e. a registration number depends on what powiat a car had been registered, not gmina). In this case we say about city county or powiat grodzki. Such cities are for example Lublin, Kraków, Gdańsk, Poznań. In Warsaw, its districts additionally have some of powiat's entitlements – like already mentioned car registration. For example, the district Wola has its own evidence and the district Ursynów – its own (and the cars from Wola have another type of registration number than these from Ursynów). But for instance the districts in Kraków do not have entitlements of powiat, so the registration numbers in Kraków are of the same type for all districts.
Document 4: Post-Soviet states: The post-Soviet states, also collectively known as the former Soviet Union (FSU) or former Soviet Republics, are the 15 independent states that emerged from the Union of Soviet Socialist Republics in its dissolution in December 1991, with Russia internationally recognised as the successor state to the Soviet Union. On March 11, 1990, Lithuania was the first to declare its independence, with Estonia and Latvia following suit in August 1991. All three Baltic states claimed continuity from the original states that existed prior to their annexation by the Soviet Union in 1944 and were admitted to the United Nations on 17 September 1991. The remaining 12 republics all subsequently seceded. 12 of the 15 states, excluding the Baltic states, initially formed the CIS and most joined CSTO, while the Baltic states focused on European Union and NATO membership.
Document 5: Dissolution of the Soviet Union: On June 14, 1987, about 5,000 people gathered again at Freedom Monument in Riga, and laid flowers to commemorate the anniversary of Stalin's mass deportation of Latvians in 1941. This was the first large demonstration in the Baltic republics to commemorate the anniversary of an event contrary to official Soviet history. The authorities did not crack down on demonstrators, which encouraged more and larger demonstrations throughout the Baltic States. The next major anniversary after the August 23 Molotov Pact demonstration was on November 18, the date of Latvia’s independence in 1918. On November 18, 1987, hundreds of police and civilian militiamen cordoned off the central square to prevent any demonstration at Freedom Monument, but thousands lined the streets of Riga in silent protest regardless.
Document 6: Molotov–Ribbentrop Pact: In mid-June 1940, when international attention was focused on the German invasion of France, Soviet NKVD troops raided border posts in Lithuania, Estonia and Latvia. State administrations were liquidated and replaced by Soviet cadres, in which 34,250 Latvians, 75,000 Lithuanians and almost 60,000 Estonians were deported or killed. Elections were held with single pro-Soviet candidates listed for many positions, with resulting peoples assemblies immediately requesting admission into the USSR, which was granted by the Soviet Union. The USSR annexed the whole of Lithuania, including the Scheschupe area, which was to be given to Germany.
Document 7: History of Latvia: The First Latvian National Awakening began in the 1850s and continued to bear fruit after World War I when, after two years of struggle in the Latvian War of Independence, Latvia finally won sovereign independence, as recognised by Soviet Russia in 1920 and by the international community in 1921. The Constitution of Latvia was adopted in 1922. Political instability and effects of the Great Depression led to the May 15, 1934 coup d'état by Prime Minister Kārlis Ulmanis. Latvia's independence was interrupted in June -- July 1940, when the country was occupied and incorporated into the Soviet Union. In 1941 it was invaded and occupied by Nazi Germany, then reconquered by the Soviets in 1944 -- 45.
Document 8: Saulkrasti Municipality: Saulkrasti Municipality () is a municipality in Vidzeme, Latvia. The municipality was formed in 2009 by reorganization of Saulkrasti town with its countryside territory, with the administrative centre being Saulkrasti. In 2010 Saulkrasti parish was created from the countryside territory of Saulkrasti town.
Document 9: Suraż: Suraż, which has a long and rich history, and was a royal town in the Kingdom of Poland, currently is one of the smallest municipalities of the country, with a population of only 1012 (as of June 30, 2012).
Document 10: Svente Parish: Svente Parish () is an administrative unit of Daugavpils Municipality, Latvia. It belongs to the Selonian part of the municipality. It is a centre of the Polish minority in Latvia.
Document 11: East Prussia: Representatives of the Polish government officially took over the civilian administration of the southern part of East Prussia on 23 May 1945. Subsequently Polish expatriates from Polish lands annexed by the Soviet Union as well as Ukrainians and Lemkos from southern Poland, expelled in Operation Vistula in 1947, were settled in the southern part of East Prussia, now the Polish Warmian-Masurian Voivodeship. In 1950 the Olsztyn Voivodeship counted 689,000 inhabitants, 22.6% of them coming from areas annexed by the Soviet Union, 10% Ukrainians, and 18.5% of them pre-war inhabitants. The remaining pre-war population was treated as Germanized Poles and a policy of re-Polonization was pursued throughout the country Most of these "Autochthones" chose to emigrate to West Germany from the 1950s through 1970s (between 1970 and 1988 55,227 persons from Warmia and Masuria moved to Western Germany). Local toponyms were Polonised by the Polish Commission for the Determination of Place Names.
Document 12: Slavs: The Gorals of southern Poland and northern Slovakia are partially descended from Romance-speaking Vlachs who migrated into the region from the 14th to 17th centuries and were absorbed into the local population. The population of Moravian Wallachia also descend of this population.
Document 13: Estonia: Another major group, inhabitants who follow Eastern Orthodox Christianity, practised chiefly by the Russian minority, and the Russian Orthodox Church is the second largest denomination with 150,000 members. The Estonian Apostolic Orthodox Church, under the Greek-Orthodox Ecumenical Patriarchate, claims another 20,000 members. Thus, the number of adherents of Lutheranism and Orthodoxy, without regard to citizenship or ethnicity, is roughly equal. Refer to the Table below. The Catholics have their Latin Apostolic Administration of Estonia.
Document 14: Gmina Suwałki: Gmina Suwałki is a rural gmina (administrative district) in Suwałki County, Podlaskie Voivodeship, in north-eastern Poland. Its seat is the town of Suwałki, although the town is not part of the territory of the gmina.
Document 15: Estonia: On 6 August 1940, Estonia was annexed by the Soviet Union as the Estonian SSR. The provisions in the Estonian constitution requiring a popular referendum to decide on joining a supra-national body were ignored. Instead the vote to join the Soviet Union was taken by those elected in the elections held the previous month. Additionally those who had failed to do their "political duty" of voting Estonia into the USSR, specifically those who had failed to have their passports stamped for voting, were condemned to death by Soviet tribunals. The repressions followed with the mass deportations carried out by the Soviets in Estonia on 14 June 1941. Many of the country's political and intellectual leaders were killed or deported to remote areas of the USSR by the Soviet authorities in 1940–1941. Repressive actions were also taken against thousands of ordinary people.
ground_truth: 5 August 1940
sub_queries: Daugavpils Municipality >> country Answer: Latvia
when did Latvia become part of the soviet union Answer: 5 August 1940