IMHO - I was there towards the very end of the war (Dec 71 - Nov 72) as the draw down was starting to take place. I think by that time McNamara's Domino Theory was proven that the loss of Vietnam would not trigger a collapse throughout SE Asia.
Just like today, the country was tired of fighting a war where the average civilian was not directly affected. No VC or NVA had bombed our territory and the draft, although about to end, made military service very unpopular. I can remember going through the Atlanta airport just before Christmas in my Class A's, boots and beret and having a hole open in the crowds around me as I walked through...like nobody wanted to get close to me or touch me. Talk about feeling like a leper!
I got back in time for Thanksgiving with my family. What should have been a joyous time was marred by my reception in California. You know - when the big one hits out there, I wish I could say I felt bad about it but to me that's no big loss. Just my sour grapes showing through.
You mentioned delusion, frustration, and tragedy. If you can read the temperament of the people today, it's a lot like the early 70's. No real progress in the war, lots of casualties, and the feeling that there was nothing that could be done to win, so they quit trying.
I wish I could be more articulate like Col Jack, TR, or some of the other QP's out there; to give you a better sense of the times. I pick up on the frustration that my son shows with what's going on - not in country - but back at home. People say they support the troops, but not the war. If you don't support the war, then don't send the troops.
I think part of the problem is the very late baby boomers and the x-generation. Life has been pretty easy for them, unlike what the depression-era folks went through. They've lost the toughness to survive and make life better.
Sorry if I ramble on - it's my frustration in getting out what I want to say.