The Russian Civil War was a multi-party civil war in the former Russian Empire, lasting from 1917 to 1922, sparked by the overthrowing of the 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.