Replacement of Cast Members
Until M*A*S*H, industry wisdom had had it that you could not successfully replace more than one principal on a sitcom. Yet M*A*S*H replaced three principal cast members. In each case the replacements portrayed more rounded characters. Two transitions occurred at the end of the third season with the departures of Wayne Rogers and McLean Stevenson.
The trade-in of Wayne Rogers's Trapper John for Mike Farrell's B. J. Hunnicut was a shift from a more caustic character to a sweeter guy—one could say from Wayne Rogers to Mister Rogers (B. J.'s overriding attribute is his longing for his family). For the most part, Trapper is a boyish prankster, a drinker, and a womanizer, in short, the character most resembling the doctors in Altman's film. However, as early as the second season, Trapper John is allowed to serve as the center of an episode ("Kim"), when he becomes fond of an abandoned Korean boy who has been found by the MASH outfit. Shortly after he gets his wife's permission to adopt the boy, the child is discovered standing in the middle of an American minefield. The show suddenly shifts from tenderness to tension as Trapper risks his life (metaphorically, love is a minefield!) to rescue the boy. It is useful to compare this episode with "B. J. Papa San" (season seven), in which B. J. becomes a surrogate father to a local Korean family. Whereas the earlier story is played mostly for suspense, the latter story emphasizes the psychology behind B. J.'s behavior.
Oddly enough, the Trapper character got to evolve offscreen. In 1979 a new Trapper, played by Pernell Roberts, reappeared as an older and wiser figure starring in his own spin-off (Trapper John, M.D. ) This avuncular incarnation of Trapper was chief of staff at a San Francisco hospital, where his wisdom was counterpointed by an idealistic but impatient younger surgeon.
The end of M*A*S*H 's third season also saw the departure of McLean Stevenson, who portrayed Henry Blake, a commander whose heart is in the right place but whose mind and body are always several steps behind. He remains a shallow figure whose goofiness in all respects except medicine is visualized by an ever-present cap bestrewn with fishing lures. Henry Blake is not really treated as a serious character until his offscreen death. "Abyssinia, Henry" ends with the announcement that on his way home his plane has been shot down.
Stevenson was replaced by Harry Morgan, who plays Colonel Potter, a career army (former cavalry) colonel whose quaintness is defined by the number of ways in which he can refer to horse dung. Potter's arrival marks a pronounced shift in tone, as he is the first regular army character who is also a regular guy.
Finally, at the beginning of the sixth season there was a change in the
chief antagonist. Frank Burns (Larry Linville) had been a cartoon figure with no redeeming qualities. Stories involving Burns come the closest to traditional witless sitcom. The typical M*A*S*H episode interwove three plots, with the Frank Burns plot nearly always providing broad comic relief and visual slapstick even if the other two plots were more serious. As an inhuman and inhumane character Burns was an easy target. He was replaced by a character inspired by William F. Buckley (Kalter, 117), the pompous Charles Emerson Winchester III, played by David Ogden Stiers. Winchester has the usual obsessiveness of a comic figure (his snobbishness) but is allowed to be a good doctor and a worthy opponent to the prank-loving Hawkeye. Winchester is also allowed to have occasional moments of generosity and compassion. While there is no doubt that the shift from Frank to Charles resulted in fewer laughs, I happen to greatly prefer the latter. It is a shift from slapstick to wit as a means of battle.
Thus virtually all the replacements of characters in M*A*S*H also precipitated a change in type of comedy. The switch from Burns to Winchester was from slapstick to wit; from Colonel Blake to Colonel Potter was from laughing at the former's incompetence to sharing the latter's sardonic sense of humor. And the replacement of Trapper by Hunnicut brought a transition from malicious to gentle humor.