My mother hated the Japanese and Germans, but especially the Japanese (because that's who my father was fighting!). Both Japan and Germany were quickly rehabilitated when they became cold war allies. But Viet Nam was never rehabilitated. They didn't just fight us, they beat us, and that was unforgivable. Even when the Vietnamese went to war with Cambodia, we (and Viet Nam's other enemy, China) supported Pol Pot over Viet Nam.

Most of the time, after governments sign the peace treaties, the belligerent populations quickly bury the hatchet and resume normal trade and travel relations, especially when faced with a common threat, as did Western Europe after WWII.

If you watch movie and TV fiction about Viet Nam, it is often hard to discern who actually won from the story line. And of course, revision and history re-writing is rampant. To this day, writing on the subject often emphasizes what we "gained" from that unfortunate adventure instead of the pointless waste which was its true legacy; or obsesses about how we were "betrayed" and "stabbed in the back" by traitors.

To this day, the South is still fighting the Civil War over and over, playing "what if", "if only" and the "blame game", and whitewashing what happened, and why. Much the same happened in Germany after WWI, when the Germans were forced to accept a bitter and unfair peace even though their arms were never decisively defeated.

American domestic politics changed after Vietnam, too. It became more divisive, more ideological. It became more about ends than it did means. In some ways, we are still fighting that war, except we're fighting it right here at home.