M*A*S*H episode
“It Happened One Night”
MASH episode-4x4 Margaret's love note to Frank
Margaret slips another love note to Frank, who, as he would admit moments later, that he always immediately tears them all up in "It Happened One Night".
Season 4, Episode # 4
Number (#76) in series (256 episodes)
Guest star(s) Christopher Allport
Darren O'Connor
Network: CBS-TV
Production code: G-502
Writer(s) Larry Gelbart and Simon Muntner
Director Gene Reynolds
Original airdate September 19, 1975
IMDb logo IMDB It Happened One Night
Episode chronology
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"Change of Command" (G‑501) "The Late Captain Pierce" (G‑507)

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"Change of Command" (G‑501) "Of Moose and Men" (G‑503)

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Season 4 episodes
List of all M*A*S*H episodes

It Happened One Night was the 76th episode of the CBS-TV series M*A*S*H television series, and also the fourth episode of the fourth season of the series. Written by Larry Gelbart and Simon Munter, and directed by Gene Reynolds, it first aired on September 26, 1975.


It's a bitterly cold night, and Hawkeye and B.J. are stuck with the overnight shift and a roomful of unruly patients. In the meantime, Margaret tells Frank that she keeps all his love letters—so he ransacks her tent to get them back.

Full plot summaryEdit

It's two degrees below zero and enemy artillery has brought blackout conditions. Hawkeye and Margaret have midnight duty in post-op, relieving Frank. Edwards, B.J.'s patient, is not recovering well after abdominal surgery and has taken 10 units of blood already.

Margaret slips Frank a love note before he leaves. She watches him read and tear up the note, so she demands to know why, for she has saved everything he's written her. Frank becomes panicked, thinking someone could find these notes if Margaret were ever killed. Frank burns the rest of Margaret's note, and then steals into her tent to retrieve his letters.

The artillery turns out to be outgoing American fire and it's bothering the patients. Radar and Hawkeye take turns trying to get the fire redirected. They fail, so Colonel Potter is brought in, who places a series of phone calls, moving up the chain of command, but the artillery never ceases.

Klinger is accidentally shot by a new night sentry on his first evening of work. It's just a scratch, but Klinger hopes it's a ticket home. Hawkeye has to break the news that he's just fine. In revolt, Klinger strips to his shorts and goes outside to catch pneumonia, but is dragged back into post-op.

Meanwhile, Edwards's condition is not improving. B.J. is back in post-op, unable to sleep from worry, and is told by Hawkeye that Edwards has been given three more units of blood and may have internal bleeding. After the last unit of B+ is used, B.J. agrees he needs to operate on Edwards again. Klinger volunteers to donate his own B+ blood for the operation.

At daybreak, Margaret returns to her tent to find it torn apart with the culprit, Frank, asleep on the floor. His search for the letters was unsuccessful and he passes off his destructive efforts as a search for a pencil.

Guest starsEdit

  • Christopher Allport as Abbott
  • Darren O'Conner as Jenkins


  • The title refers to a 1934 screwball comedy of the same title.
  • Klinger volunteers to donate blood to B.J.'s patient, stating he's type B+. In a future episode, he says he has AB-, the same as Major Charles Emerson Winchester.