Question: When did the country where Dünamünde Action was located become part of the Soviet Union?

full_context: Document 1: 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 2: 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 3: Hanover: In September 1941, through the "Action Lauterbacher" plan, a ghettoisation of the remaining Hanoverian Jewish families began. Even before the Wannsee Conference, on 15 December 1941, the first Jews from Hanover were deported to Riga. A total of 2,400 people were deported, and very few survived. During the war seven concentration camps were constructed in Hanover, in which many Jews were confined. Of the approximately 4,800 Jews who had lived in Hannover in 1938, fewer than 100 were still in the city when troops of the United States Army arrived on 10 April 1945 to occupy Hanover at the end of the war.[citation needed] Today, a memorial at the Opera Square is a reminder of the persecution of the Jews in Hanover. After the war a large group of Orthodox Jewish survivors of the nearby Bergen-Belsen concentration camp settled in Hanover.
Document 4: Jews: The persecution reached a peak in Nazi Germany's Final Solution, which led to the Holocaust and the slaughter of approximately 6 million Jews. Of the world's 15 million Jews in 1939, more than a third were killed in the Holocaust. The Holocaust—the state-led systematic persecution and genocide of European Jews (and certain communities of North African Jews in European controlled North Africa) and other minority groups of Europe during World War II by Germany and its collaborators remains the most notable modern-day persecution of Jews. The persecution and genocide were accomplished in stages. Legislation to remove the Jews from civil society was enacted years before the outbreak of World War II. Concentration camps were established in which inmates were used as slave labour until they died of exhaustion or disease. Where the Third Reich conquered new territory in Eastern Europe, specialized units called Einsatzgruppen murdered Jews and political opponents in mass shootings. Jews and Roma were crammed into ghettos before being transported hundreds of miles by freight train to extermination camps where, if they survived the journey, the majority of them were killed in gas chambers. Virtually every arm of Germany's bureaucracy was involved in the logistics of the mass murder, turning the country into what one Holocaust scholar has called "a genocidal nation."
Document 5: 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 6: Trandum leir: The woods near Trandum were an infamous site of execution of political prisoners during the Occupation of Norway by Nazi Germany. In 1945 a total of 194 bodies were found in mass graves in the woods of Trandum, including 173 Norwegians, six British and fifteen Soviet citizens. Those who could be identified were exhumed and placed in individual graves (see Bjarne Dalland).
Document 7: 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 8: 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.
Document 9: 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 10: Slavs: During World War II, Hitler's Generalplan Ost (general plan for the East) entailed killing, deporting, or enslaving the Slavic and Jewish population of occupied Eastern Europe to create Lebensraum (living space) for German settlers. The Nazi Hunger Plan and Generalplan Ost would have led to the starvation of 80 million people in the Soviet Union. These partially fulfilled plans resulted in the deaths of an estimated 19.3 million civilians and prisoners of war.
Document 11: Molotov–Ribbentrop Pact: Elimination of Polish elites and intelligentia was part of Generalplan Ost. The Intelligenzaktion, a plan to eliminate the Polish intelligentsia, Poland's 'leadership class', took place soon after the German invasion of Poland, lasting from fall of 1939 till spring of 1940. As the result of this operation in 10 regional actions about 60,000 Polish nobles, teachers, social workers, priests, judges and political activists were killed. It was continued in May 1940 when Germany launched AB-Aktion, More than 16,000 members of the intelligentsia were murdered in Operation Tannenberg alone.
Document 12: Alsace: Alsace-Lorraine was occupied by Germany in 1940 during the Second World War. Although Germany never formally annexed Alsace-Lorraine, it was incorporated into the Greater German Reich, which had been restructured into Reichsgaue. Alsace was merged with Baden, and Lorraine with the Saarland, to become part of a planned Westmark. During the war, 130,000 young men from Alsace and Lorraine were inducted into the German army against their will (malgré-nous) and in some cases, the Waffen SS. Some of the latter were involved in war crimes such as the Oradour-sur-Glane massacre. Most of them perished on the eastern front. The few that could escape fled to Switzerland or joined the resistance. In July 1944, 1500 malgré-nous were released from Soviet captivity and sent to Algiers, where they joined the Free French Forces.
Document 13: Dünamünde Action: The Dünamünde Action (Aktion Dünamünde) was an operation launched by the Nazi German occupying force and local collaborationists in Biķernieki forest, near Riga, Latvia. Its objective was to execute Jews who had recently been deported to Latvia from Germany, Austria, Bohemia and Moravia. These murders are sometimes separated into the First Dünamünde Action, occurring on March 15, 1942, and the Second Dünamünde Action on March 26, 1942. About 1,900 people were killed in the first action and 1,840 in the second. The victims were lured to their deaths by a false promise that they would receive easier work at a (non-existent) resettlement facility near a former neighbourhood in Latvia called Daugavgrīva (Dünamünde). Rather than being transported to a new facility, they were trucked to woods north of Riga, shot, and buried in previously dug mass graves. The elderly, the sick and children predominated among the victims.
Document 14: Modern history: The Holocaust (which roughly means "burnt whole") was the deliberate and systematic murder of millions of Jews and other "unwanted" during World War II by the Nazi regime in Germany. Several differing views exist regarding whether it was intended to occur from the war's beginning, or if the plans for it came about later. Regardless, persecution of Jews extended well before the war even started, such as in the Kristallnacht (Night of Broken Glass). The Nazis used propaganda to great effect to stir up anti-Semitic feelings within ordinary Germans.
Document 15: 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.
ground_truth: 5 August 1940
sub_queries: Dünamünde Action >> country Answer: Latvia
when did Latvia become part of the soviet union Answer: 5 August 1940