The real Hawkeye Pierce, H. Richard Hornberger, had some major issues with 'M*A*S*H'
It seems TV's Hawkeye Pierce couldn't charm himself out of this one.
H. Richard Hornberger wrote the book that spawned the massively popular TV show M*A*S*H under the pen name Richard Hooker. He based the character of Hawkeye Pierce after himself. Hornberger was a tremendous U.S. Army Surgeon, who performed pioneering surgeries during the Korean War. He was just as good-humored and wise-cracking as the character later portrayed by Alan Alda. According to the writer, that's where the similarlties ended, once TV started interfering with how he wrote the character.
According to History.com, Alda's anti-war sentiments began to carry over into his portrayal of the character, and that in turn led many to ascribe the same sentiments to Hornberger. The more disgruntled that Hawkeye Pierce on TV became about the war, the more it frustrated Hornberger, who told Newsweek in 1983 that the TV show "tramples on my memories."
In short, Alda was just too pacifist for M*A*S*H's original writer, whose personal politics began to get confused with the political beliefs of the actor who played the popular version of Hornberger on TV. It probably also didn't help that Hornberger was paid just $500 for each episode, as History.com notes.