I guastatori delle dighe

In the spring of 1942, the English design engineer, Barnes Wallis, is working on a revolutionary new bomb, capable of breaching Germany's hydro-electric dams. This film, with its unforgettable "Dam Busters March" by Eric Coates, recounts the story of the development of the bomb and the devising of special tactics for attacking Germany's industrial heartland. It is also a tribute to the genius of Wallis and the courage and skill of the men who made the concept work.

The great dams of western Germany, harnessing the energy of the rivers Moehne, Eder and Sorbe, were an important power source for the Nazi war effort. If the dams could be breached, then the loss of electrical energy and the collateral flooding would, it was hoped, cripple German industry and shorten the war.

As the film opens, Wallis is pondering the one central problem associated with bombing a dam. Any explosion in the water (and direct hits on the dam wall are too much to expect) is cushioned by the fluidity, and no structural damage results.

We see Wallis eagerly experimenting in his back yard, surrounded and assisted by his adoring children. His brilliant idea is this - if a bomb can be delivered at the correct shallow trajectory and the right high speed, it will 'skip' along the lake's surface like a pebble on a pond, strike the dam and slide down the wall. A depth-sensitive trigger could then detonate the bomb where it would do maximum damage.

The idea is a daring and imaginative one, and predictably enough, the various government departments are slow to see its merit. Wallis spends many disheartening hours waiting to speak to unsympathetic civil servants. In a lovely piece of ironic humour, a Whitehall mandarin points out to Wallis the difficulties inherent in obtaining a Wellington bomber for tests, and Wallis quietly suggests that his own role as the creator of the Wellington might be of some assistance.

Wallis is constantly being told that resources are scarce, that the communal effort requires sacrifices, and so forth. There is, he is told, "a very thin dividing line between inspiration and obsession". However, the eccentric genius persists, and eventually Churchill gets to hear of the idea. From that moment on, the project gathers momentum. 'Bomber' Harris, the chief of Britain's Bomber Command, sets up trials. The 'bouncing bomb' is at last a reality.

Major disappointments accompany the trials. The casing of the bomb has to be drastically re-designed, and it transpires that the aircraft will need to approach the dam considerably lower and faster than had been envisaged. The RAF's standard altimeters are useless at heights of 50 feet, and the resulting danger to crews of flying blind at almost zero altitude are unacceptable.

At this point, Commander Guy Gibson, the pilot who will lead the raid, has his own flash of inspiration. The spotlights in a variety theatre give him the idea of two converging light beams, shining downwards from aircraft to water, which will fix the plane's altitude precisely. If this all sounds a little 'Heath Robinson', it is nothing compared to the viewing gadget which is cobbled together to enable crews to align on the twin towers of the dam.

The climax of the film, the actual attack on the German dams, is rather a disappointment. Anti-aircraft tracer coming up from the German defenders is superimposed on the photographic matrix in the most amateurish of ways. The sound of the ground batteries is unrealistic, staying at a constant pitch and volume however the aircraft manoeuvre. The explosions are the poorest efforts of all, being no more than scraps of film and drawings, patched unconvincingly onto shots of a model dam.

Michael Redgrave does a commendable job of 'creating' Barnes Wallis for the screen, quintessentially English and understated, with his runner beans and his cricket jokes. The man's boyish enthusiasm comes across. In this respect the bathtub in the yard, the setting for his primitive experiments, serves two cinematic purposes, showing us the simple, unprepossessing genius of the English people, and explaining in visual terms exactly how the bomb will work.

Good use is made of genuine Air Ministry film of the bouncing bomb tests. If the ultimate effect on Germany's war capacity is exaggerated, this can be forgiven.

Richard Todd is terrific as Gibson, the tough little leader of the mission, the emotional man who is able through intense self-discipline to keep his feelings in check and do his duty. The powerful ending is almost too much to take, with the empty seats in the officers' mess, and Todd striding off in stiff-upper-lip fashion to 'write a few letters'. No English heart can fail to be stirred by that marvellous theme tune.

By God, this is as definitive as a war film gets. It's on every year, and is as much a part of Christmas as getting drunk and Monopoly. Everyone in this Sceptred isle knows the theme to Dam Busters, and it causes more people to stand up and salute than God Save The Queen. It has moustachioed R.A.F boys, politely bespectacled scientists, laughable special effects, and an entirely predictable ending. It's a British institution, and I don't know where we'd be without it. You can keep your devolution and your New Labour, I've got Dam Busters and I'm not bloody budging.

It appears that the attack sequences in The Dam Busters were the direct inspiration for the attack on the Death Star in the first Star Wars film. Some of the dialogue is word-for-word, and it is very interesting to watch these two films back to back.

Also, in the original edit of the film, the dog's name (a black labrador) was a historically accurate but socially unacceptable "Nigger". One edit changed the spoken word to "Trigger," while another release cut all scenes with the offending word. This was unfortunate, because parts of the plot became unintelligible -- the dog's name was one of the code-words used during the attack.

A very well made film, with a good script, actors and supporting cast. The film recreates the technical problems of the bombs development and squadron training. However, being made so soon after the raid the film ignores the relative lack of impact of the raid on German war production. However, the bravery of the air crews is very well portrayed. Guy Gibson, who was killed later in the war, won a Victoria Cross for his part in the raid and his leadership.

Many comments have been made about the brilliantly understated performances of Richard Todd (Guy Gibson, the RAF bombing expert who leads the raid) and Michael Redgrave (Barnes Wallis, the inventor whose vision propels the project and makes Gibson his disciple in it).

But one major theme is that of fighting a bureaucracy to fulfil a vision of how to do its work better than the ways it demands everybody use. This goes beyond a single wartime incident to give an inspiring portrait of individual talent and vision.

British wartime films are associated with "everyone pulling together in our darkest hour", but here we see those in authority as the villains (note that the Germans don't appear).

Consider the "last supper" scene before the raid. The airmen are sitting eating bacon and eggs, the last meal before bomber crews went out on a raid, many of them to die. The squadron paymaster strides up to the counter:

-bacon and eggs, please.

Woman behind counter, with strained respectfulness: are you flying tonight, sir?

• don't be stupid, woman. You know I'm the man who pays you every Thursday.

• your toast is on the table, sir.

The dinner lady understands the unwritten rule that the only men who get the traditional full English breakfast are those who might be dead a few hours later, and she rightly puts petty administrators in a completely different category, even if she has to call them 'sir'.

On the way to his plane, a pilot checks his mailbox. "Mess bill", he comments. "I can leave that till tomorrow". I think he's one of the ones who doesn't come back. A well placed line.

After the raid, Wallis meets Gibson coming off his plane, and asks him how it went. As he reels off the list of crews lost, he sees the astonishment creeping over Wallis, who suddenly realises that his obsession's fulfilment has cost the lives of so many of the young men he has been working with. Gibson's job is to deal death and receive it, and he must sooth the academic who suddenly realises what war involves:

• Wallis, you've been worrying more than any of us. Why don't you go to the doc and get some of his sleeping tablets?

• but .. what about you, Gibbo? Hadn't you better get some sleep as well?

[silence]

• Not now .. I've got some letters to write.

And as the credits roll, we see them walking away separately, Gibson to write letters to the families of 56 of his fellow airmen now presumed dead.

I don't want to neglect mentioning those who died horribly under the bombs, whose deaths are covered by triumphal scenes of the flooding after the raid. But the film itself deals with the effects war brings on a tightly-observed and well-played group of individuals, and shows these more cleverly than its modest reputation deserves.

*NB I can't vouchsafe the dialogue I've quoted, but it's pretty much what they say.