(b. Constantinople, 24 Nov. 1873; d. Berlin, 24 Apr. 1923)
Jewish; revolutionary, a leader of the Mensheviks 1905–7 and official leader 1917–20 Born in Constantinople into a middle-class liberal Jewish family (his father was a foreign correspondent) which moved back to Odessa in 1877 and in 1882 to St Petersburg, Tsederbaum became a populist when he started studying at St Petersburg University in 1891, for which he was expelled. He joined the Russian Social Democratic Labour Party in 1892 and spent two years in Vilnius developing his ideas on mass agitation. Initially he co-operated with Lenin in founding the St Petersburg Union of Struggle for the Liberation of the Working Class in 1895, and later, after three years in exile, on the Iskra newspaper. But at the 2nd Congress of the RSDLP in 1903 they parted company, Martov (as he was now known) favouring a more tolerant and open type of party than that proposed by Lenin in What is to be done?; he won the vote on this question, but Lenin's group won the later elections to the main party bodies, which enabled him to dub his opponents the Mensheviki (Minoritarians) and his group the Bolsheviki (Majoritarians). Martov became, with Dan, one of the Menshevik leaders in 1905–7 and differences, especially over revolutionary strategy, with the Bolsheviks steadily increased; the schism became permanent in 1912. Returning to Petrograd after the February Revolution of 1917 he led a group of left-wing Mensheviks who rejected the ‘national defence’ line of their leaders participating in the provisional government, while not accepting Lenin's ‘revolutionary defeatism’. After the Bolshevik revolution, when he became the official leader of the Mensheviks, he boycotted the 2nd Congress of Soviets in protest against Lenin's refusal to form a coalition; pressure on the Mensheviks increased after the closure of the Constituent Assembly in January 1918 and in June they were expelled from the Congress altogether. With the end of the Civil War in 1920 it became difficult for him to remain in Russia and his health was declining, so he left for Berlin, where he remained, editing the Socialist Courier newspaper, till his death from tuberculosis in 1923. Martov was a Marxist idealist who rejected Lenin's ‘barracks socialism’ and ‘Pugachev-style’ violent revolutionism as ‘Asiatic’, but lacked the political skill and will-power to develop a serious alternative.