Dinesh D'Souza doesn't know what he's talking about.
The military was NOT losing... anything. The US military was clobbering the VC and NVA at every major encounter and probably 99% of the minor skirmishes. We had the will and the technology to turn everything north of the DMZ into plowed earth from South Vietnamese farmers... no land mines, no cities, no towns, no people... just plowed, fertile earth.
However, back home there were dumb and incompetent politicians and diplomats being influenced by what was called the "vocal minority." Most of these were long-haired, drugged-out hippies from UC Berzerkeley.
Here's an example of their intellect. Whenever the enemy was about to be wiped out, the enemy would wave a white flag and ask for "peace negotiations" predicated upon a ceasefire. Our troops were ordered to fall back and stand down. The politicians and diplomats would do a little victory dance and pat each other on their backs and complement themselves on their brilliance. They'd troop to the negotiation table with visions of godhood.
Out in the field, the enemy was making use of the ceasefire by moving in fresh troops to replace those who were killed or injured, resupplying them, and repairing his defenses and digging them in deeper, or preparing for another abortive offensive. When they were ready, they'd start shooting. When we shot back the North Vietnamese diplomats would stomp out of the "peace negotiations" complaining we'd broken the ceasefire. And the dimwit diplomats and politicians, and the media, and the folks back home... at least the vocal minority... believed them.
We weren't just fighting North Vietnam. We were fighting the USSR and China... and we were still winning. We were also fighting the South Vietnamese Army. They were cowards who refused to fight. They also took the weapons we issued them and would sell them on the black market... to the enemy.
We were also fighting ourselves... at least at the start. Our intelligence was terrible. It was inaccurate. And often the enemy got wind of our missions and was able to move or reinforce before we got there. And the media figured out that bad news sold better than good news, so, no matter how well we were doing, they only published bad stuff. There was a plane that was shot down. The media took a few shots of it to show the public how our aircraft were shot down at the whim of the enemy. When the public lost interest in that story, they took some more shots of the same plane... from a different angle... and reported it again... and the public believed it. And they did it again... and again... until the plant life covered the darned thing.
Were it not for the hill people, we'd have been fighting the war by ourselves.
Some posted that it wasn't a war because it wasn't declared. Whatever you call it, US troops died. Some of us were wounded.
Dinesh D'Souza was born in 1961. All he has to go on is what he's been able to gather from the reports from that time... and most of those reports... from the press... were erroneous. While he was splashing around in his pabulum and messing his diapers, I was up to my butt in brown water and rice paddies. I was there. He wasn't.