Joining the Bolsheviks in 1917, he helped to organize the October Revolution with Lenin, and built up the Red Army that eventually defeated the White Russian forces in the Russian Civil War. After Lenin’s death he alienated Stalin and others with his view that socialism within the Soviet Union could not come about until revolution had occurred in western Europe and worldwide. Trotsky was eventually defeated by Stalin in the struggle for power, being expelled from the party in 1927 and exiled in 1929. After settling in Mexico in 1937, he was murdered three years later by a Stalinist assassin.