See Vietnam War
Seymour Skinner is a veteran of this war. In addition, Kent Brockman acted as a correspondent to the Vietnam War in his past, which he noted when covering the riot at Kamp Krusty with the implication that the latter event was even worse.
Seymour Skinner: POW
Unnamed Bartender: WIA (claims he got a metal [butt] in Vietnam)
Skinner's entire company: KIA
Skinner has several Posttraumatic Stress Disorder-induced flashbacks of the Vietnam war.