Leon Trotsky was a Russian Marxist revolutionary and theorist who was an influential leader in the early Soviet Union. He was born Lev Davidovich Bronstein in 1879 in Ukraine, and was a key figure in the October Revolution of 1917. Trotsky was a leader of the Red Army during the Russian Civil War and served as People's Commissar for Foreign Affairs from 1918 to 1924. He was eventually expelled from the Soviet Union in 1929 and assassinated in Mexico in 1940.