Harry Morgan, played a crazy general in an earlier MASH episode before he became Colonel Potter.
Yes, I remember that one. In fairness, he had been exposed to a horcrux. Wait....
That was a hilarious episode. Morgan played insane Major General Bartford Hamilton Steele. The scene where he speaks to Radar while inspecting the troops took 17 takes because Gary Burghoff and McLean Stevenson had too much trouble keeping from laughing! Burghoff recounted that they had not expected Morgan to be so funny, as they were more used to watching him in dramatic roles. As Burghoff put it, "We had not, never, expected him to be that off the wall. And he just killed us."