MASH premiered in 1972 and quickly became one of the most popular sitcoms in television history, a dark comedy set in a mobile Army surgical hospital during the Korean War. The show made stars of its ensemble cast, but none of them had a stranger arc than McLean Stevenson, the actor who played the unit’s commanding officer, Lieutenant Colonel Henry Blake. Stevenson found his greatest success on the show, yet he chose to leave it at the height of its popularity. That decision would define the rest of his career, and he would later call it the biggest mistake of his life.

Stevenson was born Edgar McLean Stevenson Jr. on November 14, 1927, in Normal, Illinois. His father was a cardiologist, his sister became an actress, and his family connections reached into American politics: he was a cousin of Adlai Stevenson II, the two-time Democratic presidential nominee. After high school, Stevenson joined the United States Navy, serving from 1946 to 1947 as a hospital corpsman.

He then attended Northwestern University, where he earned a bachelor’s degree in theater arts before winning a scholarship to the American Musical and Dramatic Academy. His show business career began modestly in 1962 with a summer stock production of The Music Man. He often played likable, absent-minded characters, a type that suited his easygoing screen presence. Stevenson also worked behind the camera as a comedy writer, contributing to That Was the Week That Was, a satirical news program in which Alan Alda appeared, and to The Smothers Brothers Comedy Hour, occasionally performing on both shows.

He became a regular on The Tim Conway Comedy Hour before landing a recurring role on the sitcom That Girl, where he played the boss Michael Nicholson from 1969 to 1971. When MASH was being cast, Stevenson originally auditioned for the role of Captain Benjamin “Hawkeye” Pierce, the wisecracking surgeon who would become the show’s central figure. Instead, he was persuaded to take the part of Lieutenant Colonel Henry Blake, the bumbling but well-meaning commanding officer of the 4077th. It was a role that would make him famous.

As Blake, Stevenson led the camp with a mix of incompetence and warmth, and audiences took to him immediately. He also contributed creatively, writing the episode “The Trial of Henry Blake” and providing the story for another episode, “The Army-Navy Game,” which earned him an Emmy nomination. Despite the show’s enormous success, Stevenson grew frustrated. He was the nominal leader of the unit, but the series increasingly revolved around Hawkeye, played by Alan Alda, whose sharp wit and antics dominated the screen.

Stevenson began to resent playing second fiddle to Alda’s character. During the show’s third season, he asked to be released from his contract. The producers agreed, and they decided to write his character out in a way television audiences would never forget. In the final episode of the 1974–1975 season, Colonel Henry Blake learned that his tour of duty was over.

As the episode’s emotional farewell played out, Blake boarded a plane to return home to his wife and children. The camp said goodbye, the doors closed, and the episode appeared to end on a bittersweet, hopeful note. Then the show delivered its devastating twist: word came that Blake’s plane had been shot down over the Sea of Japan. There were no survivors.

It was one of the most shocking moments in television history, and it remains one of the most famous character deaths ever broadcast. Stevenson, meanwhile, had moved on to pursue a career as a leading man. He filled in occasionally as a guest host on The Tonight Show and became a regular panelist on the game show Match Game. He then launched a string of television projects, each hoping to capture the same lightning that had struck with MASH.

The first was a variety special titled The McLean Stevenson Show in 1975, which performed poorly in the ratings, finishing 41st in its week, and a planned series never materialized. He tried again with a sitcom called The McLean Stevenson Show, which ran from 1976 to 1977. That was followed by the series In the Beginning in 1978, then Hello Larry in 1979 to 1980, which lasted two seasons, and finally Condo in 1983. All four sitcoms were cancelled, and all four failed while MASH was still on the air.

The contrast was stark. MASH continued for years after his departure, ending its historic eleven-season run in 1983 as one of the most watched series finales in television history. Stevenson never found a vehicle that matched his talents. He guest-starred on shows like The Golden Girls, The Love Boat, and Diff’rent Strokes, and he appeared alongside Harry Morgan, who had taken over MASH as Colonel Sherman Potter after Blake’s death, in the 1978 Disney film The Cat from Outer Space.

But the steady work never translated into the kind of success he had known on MASH. His career decline made him the butt of jokes in Hollywood, and Stevenson was aware of it. In 1990, he commented that some of the criticism was justified, conceding that leaving MASH was the biggest mistake of his career. The exact circumstances of his departure have been discussed for decades, with accounts suggesting he had been told the show would not last long, or that he simply wanted to be the star rather than part of an ensemble.

The sources disagree on the details, but the outcome was clear: his decision to walk away defined the rest of his professional life. Stevenson was married three times and had three children. On February 15, 1996, he was recovering from bladder cancer surgery at the Encino-Tarzana Regional Medical Center in Los Angeles when he suddenly died of a heart attack. He was 68 years old.

He was interred at Forest Lawn Hollywood Hills Cemetery. In a strange coincidence, Roger Bowen, the actor who had played Henry Blake in the 1970 film MASH that inspired the television series, died of a heart attack the day after Stevenson’s death. Stevenson’s talent was never seriously questioned, but the right writers, the right format, and the right show never came together for him after he left MASH. His story became a cautionary tale about timing, ego, and the unpredictable nature of television fame.

He remained best known for a character who was written off the show in the most dramatic way possible, and his legacy was permanently tied to the decision he made to walk away from it.