The Bolsheviks were a faction of the Russian Social Democratic Labour Party, centered around Vladimir Lenin. Following the outbreak of the war, Lenin was stunned when the large Social Democratic parties of Europe (at that time predominantly Marxist in orientation) supported their various respective countries' war efforts. Lenin (against the war in his belief that the peasants and workers of the proletariat were fighting for their class enemies) adopted the stance that what he described as an "imperialist war" ought to be turned into a civil war between the classes. He left Austria for neutral Switzerland in 1914 following the outbreak of the war and remained active in Switzerland until 1917. Following the 1917 February Revolution in Russia and the abdication of Tsar Nicholas II, he left Switzerland on a sealed train to Petrograd, where he would shortly lead the 1917 October Revolution in Russia.