He preferred being behind the camera
Robert Montgomery (May 21, 1904 – September 27, 1981).
Robert Montgomery (born Henry Montgomery Jr.) was an American film and television actor, director, and producer. He began his acting career on the stage but was soon hired by MGM. Initially assigned roles in comedies, he soon proved he was able to handle dramatic ones as well. His stay with MGM lasted 16 years and was only interrupted by WWII when he joined the navy.
He returned to MGM in 1945 and co-starred with Donna Reed and John Wayne in the John Ford-directed They Were Expendable (1945). He made his directorial debut with Lady in the Lake (1946) although he had directed a few scenes, uncredited, in They Were Expendable (1945) when John Ford took ill. He left MGM to become an independent director, preferring work behind the camera instead of in front.