Born May 10, 1876, in London; died 1938, in Paris. Figure in the French and international labor movements. Son of Charles Longuet and Karl Marx’ daughter Jenny. Lawyer by profession.
At the turn of the century, Longuet actively collaborated with the socialist press (including Humanite, published by J. Jaures). He helped found (1916) the newspaper Le Populaire, which subsequently became the central organ of the French Socialist Party. During World War I (1914-18) he headed the centrist-pacifist minority in the Socialist Party. V. I. Lenin characterized Longuet and his supporters as French Kautskyites (Poln. sobr. soch., 5th ed., vol. 31, p. 467), who conducted a policy of conciliation in relation to the social chauvinists. Longuet condemned the military intervention against Soviet Russia. After the formation of the Comintern (1919), Longuet opposed the Socialist Party’s joining the new organization. With the split of the Socialist Party and the formation of the Communist Party (1920), he became one of the leaders of the centrist wing of the socialists. He joined the leadership of the Second International. In the 1930’s Longuet participated in international organizations for the struggle against fascism and war. He advocated a rapprochement between French socialists and Communists.