What an extraordinary film! It didn't do particularly well in 1977 with either the critics or the box office, but I thought it was remarkable. They'll never make another film like this again, that's for sure.

What's so startling is that this isn't the story of one soldier, or even a platoon of soldiers. No, it's the story of an entire military campaign, the little-known Operation Market Garden which the Allied forces hoped would wrap up World War Two before the end of 1944. It's on a par with D-Day, that's how big it is. This film is based on a non-fiction book by Cornelius Ryan and tells the entire story, from the intelligence and planning stages right through to the abandonment of the operation and the Allied troops' withdrawal. It involved four of the six divisions of the First Allied Airborne Army, each containing many thousands of men, and was the largest airborne operation of all time. You'd never try to tell that story today in a mere three hours. You'd need a TV mini-series at the very least and even then you'd never try to show all of it. You'd choose your heroes. You'd focus on their story, not that of the entire operation.

The whole idea's mad. If I hadn't just watched it, I'd have never believed this could be done. What's more, Richard Attenborough even makes it look easy.

My theory is that the film didn't do well partly because of its plot structure. This is a film that's far, far bigger than any single character. It dwarfs its cast. If you're looking for straightforward "hero beats villain" adventure, this is not the film to watch. However on top of that you've also got the fact that this is a story of Allied failure. Our brave boys... um, get their arses kicked by the Germans. It's hard to see that as a boon for the box office. I wasn't in any great hurry to watch it for precisely that reason.

It's time for a little history. Operation Market Garden was a failed Allied attempt to break through the German lines at Arnheim in the Netherlands in September 1944. They had the Germans on the run, but that doesn't mean the fighting was over yet. The plan was to drop entire Allied divisions deep inside enemy territory, whereupon they'd cut through whatever reserve forces they might find there and take control of three key bridges.

What's interesting about all this is that Operation Market Garden tends to be something of a footnote in the history books. It didn't work. Montgomery called it "90% successful", but he was talking out of his arse. It's genuinely interesting to see such a comprehensive look at this lesser-known piece of military history. It has the same sweep and appeal as a really good history book. Admittedly the filmmakers have taken a bit of licence here and there, with Dirk Bogarde's portrayal of General Browning being particularly controversial, but they had lots of help from people who'd actually been there, often advising the actors playing their on-screen counterparts about what had really happened. The list includes Brian Horrocks (James Fox), James M. Gavin (Ryan O'Neal), J.O.E. Vandeleur (Michael Caine), John Frost (Anthony Hopkins) and R.E. Urquhart (Sean Connery). For quite a lot of the time, this is practically a first-hand account of what happened.

Another thing you'll never see again is the sheer scale of Attenborough's production. He effectively mounted his own military operation for the sake of the cameras. You'd do it all with CGI these days. The air drop is the most startling sequence, in which they had a thousand men and supplies really jumping out of eleven Dakota aircraft. All those parachutes look like a sea of jellyfish. That's something to rock you back on your heels.

Then there's the cast list. Sweet heavens above, that cast list! Robert Redford doesn't appear until we're two hours in! You've got Michael Caine, Sean Connery, Edward Fox, Anthony Hopkins, Ryan O'Neal, Laurence freaking Olivier, Denholm Elliott and Gene Hackman doing something that you'd never guess was meant to be a Polish accent. The list goes on and on. You've got huge stars in ten-minute roles. At one point they were even going to have Roger Moore as well, which would by itself have turned this film into 007 nerd nirvana. I didn't recognise Hopkins behind that moustache at first, but apart from him it's a riot. It's a blast, it really is, but as it happens the presence of all these stars is essential for the film. There are so many characters that we'd have been lost without familiar faces. More than a hundred actors worked on this film and I don't think that includes extras and stunt men.

Those are all side issues, though. The film itself has an interesting take on its impossible story. It's fun! This is not at all a grim film, but instead one that's chock-full of great actors having a laugh. You've got eccentric touches like the umbrella and the chicken. When our boys are lying half-dead in the mud waiting for the Germans to come and get them, a soldier gets out a flute. Believe it or not, the name I kept thinking of was Spike Milligan. Attenborough's mining a vein of black farce that I'm sure would have appealed to him. A clusterfuck as big as this is going to be rich in cock-ups and idiocies, all of which Attenborough delights in. He had me laughing out loud at the Germans' surrender scene. I mean, obviously it's a turning point that could have saved thousands of lives and an entire town had it not been for military madness, but I'd never even dreamed that what I saw could have happened.

That's the lesson of this film. There's some classic stupidity from both sides, the kind of thing you'd hardly dare to dream up if it hadn't really happened. However even that defence wasn't always enough for the critics, it seems, with for example the critics mocking the casting of a 36-year-old (Ryan O'Neal) to play Brigadier General James M. Gaven (aged 37). Anyway, coming back to the film, the German generals get their hands on a complete set of plans for Operation Market Garden, only to ignore them as fake. Some of what happens here is incredible. Absolutely unbelievable. A five-year-old wouldn't make these mistakes... or that's what you'll be thinking, anyway. And of course the outcome of all these gaffes includes, for instance, Sean Connery leading 10,000 men into a town and only getting 2,000 out again afterwards.

It's World War played as farce. Everyone involved knows they're on a deadly serious mission that's likely to get them killed, but Attenborough's direction makes it feel jaunty. Even the music is cheerful. Obviously things turn nastier in the final hour, but even there it never gets hard going.

I like the fact that the Germans are shown as being just as human as the Allies. I like the fact that everyone speaks in the language they really spoke, if necessary with subtitles. I like the way it keeps messing with your head. I still haven't seen Attenborough's earlier Oh! What A Lovely War, but I'm starting to think I should. Attenborough incidentally hadn't been planning to direct this film, wanting instead to make Gandhi, but the studios weren't keen to finance a film like that and he ended up with a deal with producer Joseph E. Levine that involved making this film first.

I should say in fairness that I seem to have liked this film more than most people. It's been called "overlong, muddled, ponderous and overbaked", although "not without some impressive moments". I'm sure it also helped that I went in not really expecting to enjoy a three-hour war movie that ended in failure. Nevertheless not only did I think it was excellent, but I'm close to calling it essential viewing for anyone with an even cursory interest in the subject matter. Theoretically it's an unfilmable story. It's sprawling, it's epic and it's all those other adjectives that can so easily be boring. However in practice it's also energetic, powerful and funny. It entertained the hell out of me and changed the way I thought of war. I won't be forgetting it in a hurry, that's for sure.