Leon Trotsky was a prominent figure in the Russian Revolution and a key leader in the early Soviet Union. He was a Marxist revolutionary and a close associate of Vladimir Lenin. Trotsky played a crucial role in the Bolshevik seizure of power in 1917 and was instrumental in the organization of the Red Army during the Russian Civil War. He was also a leading figure in the formation of the Soviet state and served as the People's Commissar for Foreign Affairs and later as the founder and commander of the Red Army. However, Trotsky eventually fell out of favor with Joseph Stalin and was expelled from the Communist Party and exiled from the Soviet Union. He continued to be a vocal critic of Stalin's leadership and wrote extensively on Marxist theory and revolutionary politics. Trotsky was assassinated in Mexico in 1940 by a Soviet agent. His ideas and contributions to Marxist theory continue to be influential in leftist and revolutionary movements around the world.