The literature on PTSD--most of the literature is American, although there's some great Canadian stuff coming out now--has noted there's quite a difference, say, between the effects of operational stress injuries, as we like to call them, depending on which war people served in. In World War II...most of the literature on PTSD specifically is from the Vietnam experience. Some of the severity there is attributed to the nature of the fighting. You didn't know where the enemy was. If any of you have read Paul Fussell's book about World War I, the lines were clear. Good guys were here and the bad guys were on the other side of the line. In Vietnam, they were everywhere.
So different wars have different battle conditions. They also have different reception conditions. When someone, say, becomes disabled and has to leave the service and return to civilian life, the climate is very different. The Americans, after Vietnam, entered a hostile climate, or at least they perceived it that way.