Context: I just finished watching Apocalypse Now, aside from being a cinematic masterpiece it seems to paint the US military as being very ill-disciplined in Vietnam. Indeed as the story progresses the main character encounters a bigger lack of discipline the further up river he goes until eventually encountering his target, a rogue Colonel whom he is tasked with killing.
This is emphasized heavily in the last US military camp they reach whilst going up river, where the chain of command has broken down almost entirely and soldiers seem to just mill about and do nothing despite being constantly under attack by the enemy. There is also a cut section (available in the re-release) where a base has fallen to ruin and there is no commanding officer at all, the soldiers just lay about all day and get drunk.
I also noted the increasing use of drugs by members of the boat crew and how, in general, the more they abused these substances the more unhinged and error-prone they became. Culminating in one of the crew dancing around with a purple flare ('purple haze, man!') on the deck of the boat, attracting the attention of hiding Viet Cong who proceed to attack and kill one of them.
Question: So how big a problem was ill-discipline in the US military at the time? Were the conscripts really so error-prone and lacking discipline, or was this just for cinematic purposes? Some figures on drug use in the military at the time would also be very interesting. Do we know how many were disciplined for using acid or smoking marijuana whilst on duty?
Apologies if this has been asked, I searched the Vietnam section of the FAQ and couldn't find anything specific on this.
The honest truth is that Apocalypse Now does not really try to attempt to portray the Vietnam War in an accurate way. The multiple why's is perhaps better reserved for /r/TrueFilm, but a neat summary is simply to say that Apocalypse Now itself is, in some interpretations, an allegory for the Vietnam War itself. The chaos, the lack of discipline, the almost dreamlike venture into the unknown has all been analyzed and contextualized as being representative of a contemporary view of the conflict itself.
Francis Ford Coppola took very large liberties with the portrayal of the actual depiction of American servicemen in Vietnam in the movie, but it is still one of my own personal favorite movies of all time.
Ill-discipline wasn't a common trend amongst frontline troops, even though this obviously depends on person to person. While conscript could be error-prone, this was usually restricted to the first few months in Vietnam before they had gained enough experience. I've written a more larger post on the reality of combat soldiers in Vietnam right here when someone asked a similar question a while ago. Most of the actual discipline problems that existed (alongside the majority of drug use etc.) were back in the line.
Being so recent these issues are probably still contentious to many, some will want to venerate the veterans memory and play down any flaws whereas others will want to use the worst excesses for their own interpretation. The scene you're referring to is, like all of AN, exaggerated for effect. Perhaps, during some of the more intense battles at places like Khe Sanh, some degree of confusion over command chains may have existed, but its highly unlikely to have done so for so long or to have been so incoherent. Both sides of these battles were quite efficient in their own way and you wouldnt last long if everything broke down in such an uncontrolled manner.
No Vietnam veteran I've heard of takes AN as a literal interpretation of how the war was fought. Although most of the ones I've talked to directly are Australian and their experiences differed somewhat from the US ones. Individual actions (like dancing around with flares) are harder to be specific about, possibly so, but I suspect a greater degree of discipline, especially when so far from base, was far more the norm.