Simpson found fairly steady movie work as various guards, cops, bouncers, and thugs until his career was interrupted by World War II, in which he served in the United States Navy as a Shore Patrolman, keeping drunken sailors and townies from killing each other, while patrolling the many L.A. bars and strip clubs. When he returned to Hollywood, it was Ford who resurrected his career, giving Simpson a small but notable role as one of Walter Brennan's sons in My Darling Clementine. Simpson would appear in a total of nine Ford films. He appeared in episode 117 of the TV Series The Lone Ranger in 1953 and episode 141 in 1954. During the late 1950s he portrayed the role of Boley on the television series Captain David Grief.