It is probably impossible to assess the content of this film in other than the context in which it was developed and presented. My own first viewing was in 1968 a matter of mere weeks before having to report for duty in the US Armed Forces. At that time I did not know whether or not I would have to go to Viet Nam as many of my friends already had. Some had already been killed or wounded in action. In this context, the film is one I will never forget.
John Wayne made this as a political film in an attempt to counter the rising tide of what he and others like him saw as treasonous protests against the government and the military over the conflict in Viet Nam. This horrid almost-war was tearing many families apart in controversy. Wayne wanted to make a patriotic statement of support for the Armed Forces who had been so good to him. He was denied several attempts at enlistment in WWII and was classified 4F. He made films to support the allied war effort then and hoped to show support again even though this was never a real war. Instead he was widely ridiculed by a rabid leftist press.
Yes, the film was definitely not accurate in the way we have come to demand of today's films. Such accuracy may have been impossible in the political climate of the day. There was deep seated anger in the upper military echelon for not being allowed to wage an actual war. Every engagement between forces was won by the Americans, but they were forbidden from the beginning to the end from pressing an attack. The result was perhaps history's worst military "Catch 22"; fight and then wait for the enemy to regroup, rearm and reattack. I still know military people who hate the entire media for the brow-beating they gave the military and Congress, who - in turn - forbade the military from pressing more aggressive action.
Wayne was also attempting to counter people in the entertainment industry whom he and others considered traitors (then and still) such as Jane Fonda, who visited and spoke in support of North Viet Nam.
It was this climate Wayne stepped into. His effort was genuine but it resulted in a cameo of the war rather than something palpable. Something that good has yet to be made. Much of what went on, real high drama and touching personal stories, has been almost entirely ignored by Hollywood. Thus, this also remains one of the few films of the hugely controversial era.