Leon Trotsky was the revolutionary name of Lev Davidovich Bronstein (1879–1940), one of the leading theorists and strategists of the Russian Bolsheviks. In the years before the Bolsheviks (or the Communists) seized power in 1917, Trotsky developed the idea of “the permanent revolution” as a way of justifying a socialist regime in a nonindustrial country like Russia. After the Communists gained control and formed the Soviet Union, Trotsky fell out with Joseph Stalin, whose policy of “socialism in one country” was directly opposed to Trotsky’s “permanent revolution.” Trotsky went into exile in 1929—the year in which he wrote The Permanent Revolution—and was living in Mexico when he was murdered in 1940 by one of Stalin’s secret agents.