I've read Sun Tzu and A Book of Five Rings as well as Clauswitz et all. The US most certainly did lose in Vietnam and we should have never been there. The politicians sent us there and then refused to let us fight the war properly. That is the fault of the politicians, not the military or the US. When we were allowed to fight it properly the fighting was finished in 11 days, it's called Operation Linebacker II and we destroyed the North Vietnamese ability to defend itself. It was launched because Nixon wanted us out and the Vietnamese wouldn't release the POWs. So we said Ok this is what happens when we don't have to fight with a blindfold on and one hand tied behind our backs. I am quite happy to discuss military history for any time from the present day all the way back to Harun al-Rashid or back to Marius if you prefer. I know it quite well.