A native of Providence, Rhode Island, Bowen majored in English at Brown University, then attended graduate school at the University of Chicago. While writing theater reviews for "The Chicago Maroon", he was asked to pen material for an improvisational troupe that included Alan Arkin and Mike Nichols. The troupe, Compass Players, evolved into The Second City. Bowen spent most of the 1960s playing "preppie" types on a number of TV & radio commercials. His first film role was 1968's "Petulia", but his big movie break came in 1970 when he landed the role of Lieutenant Colonel Henry Blake in Robert Altman's cult film "MASH". Bowen had in fact served in the U.S. Army in Korea, albeit after the Korean War had ended. (After serving in Japan as a Special Agent in the Counter Intelligence Corps (441st CIC Detachment – Bepu Field Office) from 1957–58, Bowen was sent to the 308th CIC Detachment in Seoul, South Korea in 1958.)