Supreme Soviet of the Soviet Union in the context of "1977 Constitution of the Soviet Union"

The invasion of Poland, also known as the September Campaign, Polish Campaign, and Polish Defensive War of 1939 (1 September – 6 October 1939), was a joint attack on the Republic of Poland by Nazi Germany, the Slovak Republic, and the Soviet Union, which marked the beginning of World War II. The German invasion began on 1 September 1939, one week after the signing of the Molotov–Ribbentrop Pact between Germany and the Soviet Union, and one day after the Supreme Soviet of the Soviet Union had approved the pact. The Soviets invaded Poland on 17 September. The campaign ended on 6 October with Germany and the Soviet Union dividing and annexing the whole of Poland under the terms of the German–Soviet Frontier Treaty.

The aim of the invasion was to disestablish Poland as a sovereign country, with its citizens destined for extermination. German and Slovak forces invaded Poland from the north, south, and west the morning after the Gleiwitz incident. As the Wehrmacht advanced, Polish forces withdrew from their forward bases of operation close to the Germany–Poland border to more established defense lines to the east. After the mid-September Polish defeat in the Battle of the Bzura, the Germans gained an undisputed advantage. Polish forces then withdrew to the southeast where they prepared for a long defence of the Romanian Bridgehead and awaited expected support and relief from France and the United Kingdom. On 3 September, based on their alliance agreements with Poland, the United Kingdom and France declared war on Germany; in the end their aid to Poland was very limited. France invaded a small part of Germany in the Saar Offensive, and the Polish army was effectively defeated even before the British Expeditionary Force could be transported to continental Europe.

The Soviet Union was formally dissolved as a sovereign state and subject of international law on 26 December 1991 by Declaration No. 142-N of the Soviet of the Republics of the Supreme Soviet of the Soviet Union. It also brought an end to the Soviet Union's federal government and CPSU general secretary Mikhail Gorbachev's effort to reform the Soviet political and economic system in an attempt to stop a period of political stalemate and economic backslide.

The Soviet Union had experienced internal stagnation and ethnic separatism. Although highly centralized until its final years, the country was made up of 15 top-level republics that served as the homelands for different ethnicities. By late 1991, amid a catastrophic political crisis, with several republics already departing the Union and Gorbachev continuing the waning of centralized power, the leaders of three of its founding members, the Russian, Belarusian, and Ukrainian SSRs, declared that the Soviet Union no longer existed. Eight more republics joined their declaration shortly thereafter. Gorbachev resigned on 25 December 1991 and what was left of the Soviet parliament voted to dissolve the union the following day.

The Presidium of the Supreme Soviet (Russian: Президиум Верховного Совета, romanized: Prezidium Verkhovnogo Soveta) was the standing organ of the highest body of state authority in the Union of Soviet Socialist Republics (USSR). The presidium was elected by joint session of both houses of the Supreme Soviet to act on its behalf while the Supreme Soviet was not in session. By the 1936 and 1977 Soviet Constitution, the Presidium of the Supreme Soviet served as the collective head of state of the USSR. In all its activities, the Presidium was accountable to the Supreme Soviet of the USSR.

Beside the all-Union body they were also in all union republics (e.g.: Presidium of the Supreme Soviet of the Russian SFSR, Presidium of the Ukrainian SSR, etc.) and other regions including autonomous republics. Structure and functions of the presidiums in these republics were virtually identical.

The Government of the Union of Soviet Socialist Republics (USSR) was the executive and administrative organ of the highest body of state authority, the All-Union Supreme Soviet. It was formed on 30 December 1922 and abolished on 26 December 1991. The government was headed by a chairman, most commonly referred to as the premier of the Soviet Union, and several deputy chairmen throughout its existence. The Communist Party of the Soviet Union (CPSU), as "The leading and guiding force of Soviet society and the nucleus of its political system" per Article 6 of the state constitution, controlled the government by holding a two-thirds majority in the All-Union Supreme Soviet. The government underwent several name changes throughout its history, and was known as the Council of People's Commissars from 1922 to 1946, the Council of Ministers from 1946 to 1991, the Cabinet of Ministers from January to August 1991 and the Committee on the Operational Management of the National Economy from August to December 1991.

The government chairman was nominated by the Central Committee of the Communist Party of the Soviet Union (CPSU) and elected by delegates at the first plenary session of a newly elected Supreme Soviet of the Soviet Union. Certain governments, such as Ryzhkov's second government, had more than 100 government ministers, serving as first deputy premiers, deputy premiers, government ministers or heads of state committees/commissions; they were chosen by the premier and confirmed by the Supreme Soviet. The Government of the Soviet Union exercised its executive powers in conformity with the constitution of the Soviet Union and legislation enacted by the Supreme Soviet. The first government was led by Vladimir Lenin, and the last government was led by Valentin Pavlov.

Yuri Alekseyevich Gagarin (9 March 1934 – 27 March 1968) was a Soviet pilot and cosmonaut who, aboard the first successful crewed spaceflight, became the first person to journey into outer space. Travelling on Vostok 1, Gagarin completed one orbit of Earth on 12 April 1961, with his flight taking 108 minutes. By achieving this major milestone for the Soviet Union amidst the Space Race, he became an international celebrity and was awarded many medals and titles, including his country's highest distinction: Hero of the Soviet Union.

Hailing from the village of Klushino in the Russian SFSR, Gagarin was a foundryman at a steel plant in Lyubertsy in his youth. He later joined the Soviet Air Forces as a pilot and was stationed at the Luostari Air Base, near the Norway–Soviet Union border, before his selection for the Soviet space programme alongside five other cosmonauts. Following his spaceflight, Gagarin became the deputy training director of the Cosmonaut Training Centre, which was later named after him. He was also elected as a deputy of the Soviet of the Union in 1962 and then to the Soviet of Nationalities, the lower and upper chambers of the Supreme Soviet respectively.

Brest Fortress (Belarusian: Брэсцкая крэпасць, romanized: Bresckaja krepasć; Russian: Брестская крепость, romanized: Brestskaya krepost; Polish: Twierdza brzeska; Lithuanian: Bresto tvirtovė), formerly known as Brest-Litovsk Fortress, is a 19th-century fortress in Brest, Belarus. In 1965, the title Hero Fortress was given to the fortress to commemorate the defence of the frontier stronghold during the first week of Operation Barbarossa, when Axis forces invaded the Soviet Union on 22 June 1941. The title "Hero Fortress" corresponds to the title "Hero City" that the Presidium of the Supreme Soviet of the Soviet Union awarded to twelve Soviet cities.