Interesting reading is Halberstams Best and the Brightest which gives a biographical look at the players. As a Harvard grad, Class of 55 he posits that JFK would never have supported the build up that Johnson did. Of course this flies in the face of his other theory that the Dems were saddled with the fear of another China loss.
TET68 was a watershed because of the way the media portrayed it. They portrayed it as a complete surprise to our intelligence community and a military defeat. They reinforced that view by continually broadcasting footage of wounded marines riding out on top of a tank at Hue and providing nightly broadcasts of the struggle to recapture the city. It was the only story for them. Walter Conkrite saying night after night how terrible it all was. The offensive, which was country-wide, had been defeated everywhere else. It was a major defeat for Giap and his staff; Charlie was never able to take the field again. From that point on the NVA regulars were the sole opposition. Giap and Uncle Ho were scared to death that the US and ARVN would come North, but the gutless wonders in Washington had no vision of that in their proportional response.
The NVA were finally successful because the DemoRat congress would not live up to their pledge to provide air support if the NVA invaded the South. The nightly news had long made us weary and we had no stomach to continue.
Another one I am saving some kidney space for.