This documentary covers the Vietnam War chronologically with an emphasis on military aspects. To anyone getting acquainted with the history of the war, it may be irrelevant to know exactly which American divisions took part in, say, Operation Hastings, but it doesn't hurt them either.
On the other hand, the film provides pretty good insight regarding the weapons used, strategic and political considerations etc. and what's more important, it does so in a dispassionate and non-partisan way, which I deem as a good thing. We don't see the footage of the officer shooting a Vietcong in the head, or the photo of the naked girl running away from a Napalm bombing. There are no interviews to veterans or politicians of the time. Very rarely we hear other voices apart from the narrator.
You need to see this if you want an introduction to the time line of the Vietnam war, which is exposed brilliantly.