He moved to St Petersburg and became a professional revolutionary. Like many of his contemporaries, he was arrested and exiled to Siberia, where he married Nadezhda Krupskaya. After his Siberian exile, Lenin - the pseudonym he adopted in 1901 - spent most of the subsequent decade and a half in western Europe, where he emerged as a prominent figure in the international revolutionary movement and became the leader of the 'Bolshevik' faction of the Russian Social Democratic Worker's Party.In 1917, exhausted by World War One, Russia was ripe for change. Assisted by the Germans, who hoped that he would undermine the Russian war effort, Lenin returned home and started working against the provisional government that had overthrown the tsarist regime. He eventually led what was soon to be known as the October Revolution, but was effectively a coup d'etat. Almost three years of civil war followed. The Bolsheviks were victorious and assumed total control of the country. During this period of revolution, war and famine, Lenin demonstrated a chilling disregard for the sufferings of his fellow countrymen and mercilessly crushed any opposition.