Expelled from university for his radical policies, Lenin completed his law degree as an external student in 1891. 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.