Okay, okay, early on they quote Gen. Bruce Palmer, one of the few upper echelon officers who saw that war clearly and yet didn't suffer an end to his career because of it, as saying the war was "the first clear failure" in American military history. But that's a quote. Which reduces it to a matter of opinion. I suppose you could argue about the "first" business--Woodrow Wilson's sending US troops into Mexico in 1914 and into Russia in support of the Whites in 1918 come immediately to mind. (What? You didn't know the US intervened militarily in the Russian Revolution?) But the clear failure of the US in Vietnam is not open to debate, no matter how fervently some might wish it.
And yes, they quote several others, both military critics of Westmoreland's leadership and historians critical of US conduct, as well as some passages from Robert McNamara's 1995 mea culpa. But how could they do less? Continuing to portray a war fought forty years ago as a matter of unsettled debate and not (largely) settled history is disingenuous, and it's done as a sop to political forces which don't want to hear the truth. It does not require a "critic" of the war to note that Westmoreland's attrition strategy failed. It failed. It's not a matter of opinion that our "air mobility" was ineffective. It was. In the clearest possible terms. Returning to the language of controversy ignores the salient lesson of that war, that massive application of military force does not guarantee victory on the battlefield this side of visiting nuclear winter on the globe. It's a lesson we chose to write ourselves out of after the fact, and our failure to learn it is clear in Iraq. We have an entire generation which has grown up being told that it is impossible for the US military to suffer defeat, that our loss in Vietnam was the result of domestic politics and somehow not "real". And three decades later we send an insufficient force to the Middle East with no plans for anything other than a rousing success.
And someone please explain this to me:
The overthrow and killing of President Ngo Dinh Diem of South Vietnam in a coup by officers in November 1963...
The paper which published the Pentagon Papers now maintains that it was a coup by ARVN colonels that deposed Diem. The mind reels.
We dishonor 57,000 dead Americans when we turn their cause into fable. And what's more, we make it that much easier to throw away more lives in empty, dishonest, and ill-considered international adventures. RIP, General.