Adopted name of Lev Davidovitch Bronstein (1879-1940) joined the Bolshevik party and took a leading part ip the seizure of power and raising the Red Army which fought the Civil War 1918-1920.
In the struggle for power that followed Lenin's death in 1924, Stalin defeated him, and this and other differences with the Communist Party led to his exile in 1929. Trotsky settled in Mexico, where he was assassinated with an ice pick, possibly at Stalin's instigation. Trotsky believed in world revolution and in permanent revolution, and was an uncompromising, if liberal, idealist.
Although as a young man Trotsky admired Lenin when he worked with him organizing the revolution of 1917 he objected to Lenin's dictatorial ways. Trotsky's later works are critical of the Soviet regime, for example The Revolution Betrayed in 1937. His greatest work is his magisterial History of the Russian Revolution 1932-1933.