The Bolsheviks, led by Vladimir Lenin, were a radical faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split with the Mensheviks at the Second Party Congress in 1903. The Bolshevik party, formally established in 1912, seized power in Russia in the October Revolution of 1917 and was later renamed the Russian Communist Party, All-Union Communist Party, and ultimately the Communist Party of the Soviet Union. Its ideology, based on Leninist and later Marxist–Leninist principles, became known as Bolshevism.