The Union of Soviet Socialist Republics (more commonly called the Soviet Union or the USSR, Russian: CCCP) was a self-proclaimed Communist state that existed from 1922 to 1991, covering much of the area of the former Russian Empire. For virtually all of its history it was governed exclusively by the Communist Party of the Soviet Union (CPSU). Although at first formed of four Soviet Socialist Republics, this number had grown, through a combination of conquest and re-allocation, to 16 by the end of 1940; it was reduced to 15 in 1956 and this remained the total until the final days (see "Catalogs" above for a table).
Although the exact borders of the Soviet Union varied, by the end of the Second World War in 1945 it covered the vast majority of territory that once belonged to the Russian Empire with the exception of Poland and Finland, but with the addition of kaliningrad.
The Soviet Union was often referred to as Russia, and although this was incorrect, Russia (under the guise of the Russian Soviet Federal Socialist Republic or RSFSR) was certainly by far the largest and most powerful and developed state within the Union.
The Soviet Union was run by a single-party system under the Communist Party of the Soviet Union. Its primary organs were, from 1936, the Party's Politburo and Central Committee, and Sovmin, the Council of Ministers. The bicameral Supreme Soviet, sometimes assimilated to the Communist Party, was formally an organ not of the Party but of the Soviet state. (The word "soviet" is Russian for "council" or "assembly.")
The history of the Soviet Union is grounded in the history of Russia as a whole, and its establishment in the two revolutions of 1917.
The Soviet legacy includes serious economic, military, political, and social issues.
The Tsarist Government was toppled in February 1917 following the February Revolution. The short-lived state that followed underwent two Prime Ministers, Prince Georgy L'vov and Alexander Kerensky. Although the Bolsheviks were imprisoned after the failed July Days attempt at establishing a Bolshevik government, they were released after the Kornilov Affair, in which General Kornilov attempted to overthrow the Republican government and establish a military dictatorship, as a precautionary measure.
Preceding the Second Congress of Soviets in Petrograd, the Central Committee of the Bolshevik Party voted with an almost unanimous vote (only two voted against: Gregory Zinoviev and Lev Kamenev) to initiate a revolution in the context of the Congress. This came to pass as in November (new dating system) the Bolsheviks overthrew the government and established their own Workers' and Peasants' Coalition Government.
With the Tsar and his family imprisoned in Tobolsk, and red forces spreading across Russia, discontent with the Bolsheviks also grew. Forces referred to as the White Army (white being a color of Monarchism) led by Admiral Kolchak, who now declared himself the Supreme Ruler of Russia with his forces in Omsk, took up arms in rebellion. While the White Army is associated with the Monarchist movement, it is best understood as a coalition of Anti-Bolshevik forces including Socialists, Mensheviks, and regionalists. This political division would haunt the Whites thru-out the war.
While Kolchak rallied forces in Siberia, the Lieutenant General Anton Denikin rallied forces in the Caucasus with the help of sympathetic [[Don Cossack] forces. However, after the capture of the Cossack's home territories, many would refuse to join him in the attempted advance on Moscow. Both Kolchak and Denikin would be assisted by the Allied Powers who recently had finished their war against Germany. Britain alone would send 100 million Pounds to the Whites in support of their efforts. Some in Europe, such as Winston Churchill, even called for an invasion of Russia to stop the Reds. Ultimately, much of the Allied aid was squandered by the elites in the White Army.
After a bloody 6 years of war, ultimately the Bolsheviks would achieve victory and declare the Union of Soviet Socialist Republics. While estimates vary, around 8 million people of all backgrounds died as a direct result of the Civil War.