Bob Ross was an air-force member from the 60s to 80s, ending at first sergeant. As far as I know he spent his career in non-combat rolls in Alaska, but he really was what some would call a "Vietnam era veteran".

And, in fact, his whole art shtick of speaking softly and calmly is because as a sergeant he had to yell all the time. He hated it and wanted to do something where he didn't have to be hyper-aggressive and yell.