Hayden may be the only major Hollywood figure whose real life was actually more exciting and adventurous than anything he ever did in film. He left home for the sea at age 17, first as a ship's boy, then as doryman on the Grand Banks, as a seaman and fireman on numerous vessels before getting his first command at age 19. He sailed around the world a number of times, becoming a well-known and highly respected ship's captain.
When the US entered World War II, Hayden changed his name to John Hamilton to obscure his Hollywood past, and joined the Office of Strategic Services--the predecessor of the CIA--headed by Col. "Wild Bill" Donovan, whose son Hayden had sailed with. Trained in guerrilla warfare, Hayden operated a fishing boat off of Yugoslavia to pick up downed Allied pilots and to supply Tito's Communist partisans. He won a Silver Star and a promotion to captain by the time he was discharged in 1945. He had also become enthusiastic about Communism, and briefly joined the Communist Party after he returned to Hollywood.
After the war, Hayden returned to film work, which he despised, in order to pay for a succession of sailing vessels. As the Red Scare deepened in U.S., he cooperated with the House Un-American Activities Committee, confessing his brief Communist ties, and naming other Hollywood people who were associated with communism in the 40s. He regretted this action from then on, holding himself in enormous contempt for what he considered "ratting"
His resume includes some of the greatest films-noir ever produced: Manhandled (1949), The Asphalt Jungle (1950), Crime Wave (1954), Johnny Guitar (1954), Naked Alibi (1954), Suddenly (1954), The Come On (1956), The Killing (1956) and Crime of Passion (1957).