Maybe you weren’t around during the Tet Offensive, but I remember it well. What caught America’s attention was that after years of serious fighting and hundreds of thousands of troops and repeated assurances that we were on our way to victory, Tet showed us that there was no secure area anywhere in Vietnam. Our own embassy was almost overrun. Sure we beat them back, just like we won every major engagement. We had too much firepower, etc..But it showed us that we were a long way from “winning” the war and made many people wonder what we were doing there.
I was in Danang, Vietnam during the Tet offensive. I remember it very well.