The Bolsheviks were a faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split apart from the Menshevik faction at the Second Party Congress in 1903. The Bolsheviks were the majority faction in a crucial vote, hence their name. They ultimately became the Communist Party of the Soviet Union. The Bolsheviks came to power in Russia during the October Revolution phase of the Russian Revolution of 1917, and founded the Soviet Union.