It is many years since I have seen it, but it is quite clearly a powerful anti-war film.
The Japanese were empire builders, as the British were, and normally show how their soldiers swept through and captured the Philippines and Singapore with the imperialist zeal that they believed was unconquerable. This film shows quite literally the reverse: the soldiers, in retreat, have to hide in the jungle to avoid capture and death by the Americans.
You only ever glimpse the Americans soldiers through the jungle. They appear like spacemen - like creatures form another planet - and so belong to another world, far removed from the one the Japanese soldiers are forced to live in when hiding and trying to survive in the jungle.
The conditions the Japanese soldiers were reduced to are shown in one extraordinary scene, when one soldier - whom we have seen previously as being the embodiment of fanatical zeal - is sitting under a tree, wounded in the stomach and clearly dying.
When he is found by another Japanese soldier, he explains that he is dying and asks the second soldier stay with him. The dying man says: "If you do, you can eat me." The second man walks on, and you are just left with the image of this poor man under a tree.
Every image in the film burns into your mind. What is so incredibly impressive now, as then, is the portrait the film paints of a defeated people; it looks at the nature of defeat among people who believed they could never lose.
So it's a film about defeat and the cost of defeat - to humanity and to soldiers particularly - in any war. It is a very powerful anti-war message. The link with Apocalypse Now is that this second film is also about an army that loses a war, although whether America lost the Vietnam war is still very much a subject of hot dispute in the US. Culturally, it is hard to come to terms with.
I remember sitting in Charles Airport, in South Carolina - a very small airport used mainly by the military en route to Nicaragua - with a Vietnam veteran.
As we sat, a young soldier came through and was greeted by his parents and the man next to me said: "What you are watching there is what happened through hundreds of little airports all through America when soldiers came back from Vietnam, and the look in their eyes was always the same: there was a powerful sense that what they had experienced in Vietnam they would not be able to explain easily to the folks at home."
At the same time, said my companion, all the things that happened were born at home.
He expressed something I profoundly believe: that if you want to track violence in any society, it is always at the centre, not in the peripheries.
That, essentially, is what Coppola was exploring in Apocalypse Now, in the journey down the river to what he called the heart of darkness. If you journey deep enough into any heart, you will find its dark side.
When Martin Sheen finds Marlon Brando deep in the jungle it is, for me, the most electrifying aspect of the film, as he has just taken a journey to a place where it is impossible to return. Sheen has crossed the river to Hell and it is peopled by American soldiers.
People find this scene incomprehensible because it was not explained. But I did not think you needed an explanation. It is like the man under tree - an image showing more than words could.
And that, to me, is the essence of cinema.