Soviet leader who joined the Social Democratic Party (1901) and sided with the Bolshevik faction when the party split in 1903. He was exiled to Siberia for ordering Bolshevik deputies in the Duma to oppose World War I. In 1917 he presided over the Second All-Russian Congress of Soviets. On Lenin’s death in 1924 Kamenev, Zinoviev, and Stalin formed a triumvirate to exclude Kamenev’s brother-in-law, Trotsky, from power. In 1936 he was accused of complicity in the murder of Kirov in the first public show trial of Stalin’s great purge, and was shot.