This is the first biography in any language of 'Comrade Prince' D. S. Mirsky (1890-1939), who uniquely participated in three distinctive episodes of modern European culture. In late imperial St Petersburg he was a poet, a student of Oriental languages and ancient history, and also a Guards officer. After fighting in World War I and the Russian Civil War, Mirsky emigrated, taught at London University, and became a literary critic and historian, writing prolifically in English, and also in Russian for the Paris-centred emigration, especially as a leading member of the Eurasian movement. His closest literary relationships were with Marina Tsvetaeva and Aleksei Remizov, and later with Maksim Gorky. In 1926-7 he published A History of Russian Literature, written in English, which remains the standard introduction to the subject. While in London he lived in Bloomsbury and knew the Woolfs; he also knew T. S. Eliot, and was the first Russian critic to write about him. Mirsky became a Communist in 1931 and returned to Stalin's Moscow the following year, becoming a prominent Soviet critic, and in particular championing Boris Pasternak. In 1937 he was arrested, and died in the Gulag. This biography draws on much unpublished material, including Mirsky's NKVD files.