It is very rare for a television to survive a major cast change, but M*A*S*H underwent two major cast changes during its 11 year run (three if you count the departure of Gary Burghoff’s Radar). Between seasons three and four, 20th Century Fox Television announced the replacement for the departed Col. Henry Blake as Harry Morgan’s Col. Sherman Potter. They also announced that Mike Farrell would be joining the cast. Then, between seasons five and six, another cast change was made when Larry Linville’s Major Frank Burns left the 4077th and was replaced by David Ogden Stiers’ Major Charles Emerson Winchester. After the death of Col. Blake at the end of season three, M*A*S*H did suffer in the ratings, but it bounced back and did well until the finale. Let’s look at how the cast changes were announced in two press releases.

Beginning in 1975, the first press release introduced fans to Morgan and Farrell. The release states that Morgan joined M*A*S*H to play “the new commanding officer, Col. Sherman Potter, a career army man and former cavalry officer who manages to make the adjustment to the madcap Mobile Army Surgical Hospital scene, despite his background in more orthodox surroundings.” In this single sentence, we see the premise for Col. Potter’s first episode (and the second episode of season four). When Hawkeye finds out that Col. Potter is “regular army,” he is concerned whether his surgical skills will be up to par. Of course, we find out that Col. Potter fits in well at the 4077th, but in July 1975, that would have been an unknown to audiences. He was the replacement for the popular Col. Blake, who died at the end of the previous season. Fans had a strong response to Blake’s death, but to their credit, Larry Gelbart and Gene Reynolds stood behind the decision to kill off the character.
While Morgan was a fairly well known actor in 1975, Farrell was newer, so in this release we get more of his acting background. The release states, “Farrell is cast as Capt. B.J. Hunnicutt, a clean-cut young surgeon recently drafted and recently married, who finds the off-duty hijinks in Korea a bit strange after his civilian residency.” We meet BJ in the first episode of season four, and he is very new to the concept of combat surgery. He quickly learns, however, and fits right in at the 4077th. What is most interesting about this release to me is what isn’t said. It is not stated that Farrell was the replacement for Wayne Rogers’ Capt. Trapper McIntyre. The release doesn’t mention Rogers at all, nor does it list him with the regular cast. It is possible that another release was sent about Rogers’ departure from M*A*S*H, but it is likely that Fox wanted to quietly announce the cast change.
The second release in this week’s post is from August 1977, just before the premiere of M*A*S*H‘s sixth season. This release gives us a preview of the first episode of the season in which a new character (Stiers as Maj. Winchester) will join the 4077th. Unlike the previous release which glossed over BJ being the replacement for Trapper, this press release owns it. “Winchester becomes a reluctant member of the M*A*S*H company when his predecessor, Maj. Frank Burns, still suffering from the trauma of his blighted romance with ‘Hot Lips,’ goes AWOL and receives a permanent transfer.” So the audience would likely have known before the episode aired that they were going to meet a new character and that Frank was gone. The rest of the release goes on to discuss the cast and details of the season premiere episode. I suspect that a release announcing Stiers joining M*A*S*H was released earlier in the summer of 1977.
Seeing how casually the cast changes in M*A*S*H were handled might be part of the reason why they worked. Of course, the series’ writing and attention paid to crafting the new characters is the main reason why they all worked out. Col. Potter was a better commanding officer than Col. Blake. BJ was a very different character from Trapper, but he was just as likable and close to Hawkeye. And, of course, Charles was a very skilled surgeon who played a great foil for Hawkeye and BJ. Unlike Frank who was often the butt of their jokes, Charles gave Hawkeye and BJ a run for their money! I think that there is a lot to be learned from how M*A*S*H handled cast changes, both on and off camera, because they were well thought out and well orchestrated.