en the anti-communist White movement and the new Soviet regime with its Red Army. Russia lost its Ukrainian, Polish, Baltic, and Finnish territories by signing the Treaty of Brest-Litovsk that concluded hostilities with the Central Powers in World War I. The Allied powers launched an unsuccessful military intervention in support of anti-Communist forces, while both the Bolsheviks and White movement carried out campaigns of deportations and executions against each other, known respectively as the Red Terror and White Terror. By the end of the civil war, the Russian economy and infrastructure were heavily damaged. Millions became White émigrés, and the Povolzhye famine of 1921 claimed up to 5 million victims.
The Russian Soviet Federative Socialist Republic (called Russian Socialist Federative Soviet Republic at the time) together with the Ukrainian, Byelorussian, and Transcaucasion Soviet Socialist Republics, formed the Union of Soviet Socialist Republics (USSR), or Soviet Union, on 30 December 1922. Out of the 15 total republics that would make up the USSR, the Russian SFSR was the largest in terms of size, and making up over half of the total USSR population, dominated the union for its entire 69-year history.
Following Lenin's death in 1924, a troika had been designated to govern the Soviet Union. However, Joseph Stalin, an elected General Secretary of the Communist Party, managed to put down all opposition groups within the party and consolidate much power in his hands. Leon Trotsky, the main proponent of the world revolution, was exiled from the Soviet Union in 1929, and Stalin's idea of Socialism in One Country became the primary line. The continued internal struggle in the Bolshevik party culminated in the Great Purge, a period of mass repressions in 1937–38, in which hundreds of thousands of people were executed, including original party members and military leaders convicted in coup d'état plots.
Under Stalin's leadership, the
