James Arness was shot by a sniper at Anzio, the sniper shot several members of his platoon and hit him in the left foot. He lost the front half of his left foot due to the wound. If you watch Gunsmoke episodes close you see his limp and difficulty he had mounting a horse at times. Buck, his buckskin, was the only horse he wanted to use in films and he hated to ride horses because of his foot. The idiot producer had him walk up hill to boot hill in the opening of the original episodes.
