The Russian Civil War was a multi-party civil war in the former Russian Empire sparked by the overthrowing of the social-democratic Russian Provisional Government in the October Revolution, as many factions vied to determine Russia's political future. It resulted in the formation of the Russian Socialist Federative Soviet Republic and later the Soviet Union in most of its territory. Its finale marked the end of the Russian Revolution, which was one of the key events of the 20th century.

The October Revolution, also known as the Great October Socialist Revolution, October coup, or Bolshevik coup was a revolution in Russia led by the Bolshevik Party of Vladimir Lenin that was a key moment in the larger Russian Revolution of 1917–1923. It was the second revolutionary change of government in Russia in 1917. It took place through an armed insurrection in Petrograd on 7 November 1917 [O.S. 25 October]. It was the precipitating event of the Russian Civil War.