While a teacher in San Francisco in the 1930s, he became active in the American Trotskyist movement and joined the newly founded Socialist Workers Party in 1938.
[1] The SWP proposed that Charles Cornell go to Coyoacán, Mexico, where Leon Trotsky was living in exile to work as one of his bodyguards.
At first the police suspected Trotsky and his secretaries of having organised the raid, but soon realized this to be wrong.
Cornell, who was present, could not prevent the fatal attack on Trotsky three months later on August 20, 1940, carried out by the Stalinist agent Ramón Mercader, who had infiltrated the household and stabbed him in the back of the head with an icepick.
Eventually he gave up political activities and went into the real-estate business, first in Connecticut, and later in Arizona.