Trotsky was a Marxist intellectual whose ideas form the basis of Trotskyism, a Communist ideology based on the theory of worldwide revolution. He was a crucial figure in the 1917 Bolshevik Revolution in Russia and organized the Red Army in the civil war that followed. After a power struggle with Joseph Stalin in the 1920s, Trotsky was exiled from the USSR. In 1940, he was assassinated in Mexico by an alleged Soviet agent with ties to Stalin.