Marking the 70-year anniversary of the actual raid, Taylor Downing reviews the classic war movie The Dam Busters

At 7.30am on 17 May 1943, Flying Officer Jerry Fray took off in his photo-reconnaissance Spitfire for a damage assessment sortie over Germany. At 30,000 feet and about 100 miles from the Ruhr, he could see what looked like a bank of cloud to his east, but as he flew closer he realised it was the sun glinting on the mass of water that filled the valley below the Möhne dam.
He was stunned by the fact that the floodwater was about a mile wide in the valley and was still gushing through a massive breach in the dam wall. He was overcome by the immensity of the destruction below him and wondered ‘if the powers that be realised just how much damage had been done’.

He took a series of photos and then went on to the Eder valley, where the damage and flooding looked even more extensive. He took a second set of photos and then spotted two enemy aircraft approaching. So he turned and in his un-armed photo-recon Spitfire headed for home at full speed.

Front-page news

The pin-sharp aerial photos Fray took were on the front page of every British newspaper the following morning. A short communiqué issued by the Air Ministry outlined the targets as three Ruhr dams and added, ‘The attacks were pressed home from a very low level with great determination and coolness in the face of fierce resistance.’

Realising how important the dams were to the supply of water and hydro-electric power for the coke ovens and steel mills at the heart of the German war economy, the press went into overdrive. The Daily Telegraph proclaimed on its front page, ‘With one single blow the RAF has precipitated what may prove to be the greatest industrial disaster yet inflicted on Germany in this war.’ The legend of the Dam Busters was born.

The story of how a brilliant but whacky inventor, Barnes Wallis, comes up with the idea of a bouncing bomb and of how a new squadron of some of the best fliers in the RAF, 617 Squadron, is put together under Wing Commander Guy Gibson to carry out the daring, high-risk mission to bomb the dams is well known. The raid has probably become the most famous RAF bombing mission of the war. That is partly down to the success of one of the best British war films ever produced. The Dam Busters was premiered on the 12th anniversary of the raid in May 1955. It still feels real and is compelling viewing nearly 60 years later.

The producers of the Associated British Picture Company wanted to make their film as realistic as possible. It was shot in black and white deliberately to give it a grainy, authentic 1940s feel. The script was written by the celebrated playwright R C Sherriff (best known for Journey’s End in 1929, the drama set in a World War One dugout). But it was based on Paul Brickhill’s book The Dam Busters published in 1951, and much of the dialogue is taken from the book. This in itself derived much of its flying details from Guy Gibson’s own book Enemy Coast Ahead, written in 1944 but published posthumously in 1946.

Attention to detail

The production company consulted many of the survivors as well as the next-of-kin of those who had died on this or subsequent missions. They filmed many of the scenes at RAF Scampton, from where 617 Squadron had actually flown in 1943, and at the headquarters of 5 Bombing Group at Grantham, from where the mission had been directed.
The care and attention paid to detail in the film paid off. Most of the central actors playing the flight crews look authentic and feel right for the parts they play. Richard Todd playing the role that helped to make his movie career was actually 35-years-old playing Guy Gibson who was only 24. But he is perfect for the part and had his own heroic wartime experience to draw on for the role.

Todd had been in the 6th Airborne Division and had jumped at Pegasus Bridge on D-Day. The scenes in the officers’ mess and around RAF Scampton have an authenticity it would be difficult to recapture today, right down to the fact that crews were offered bacon and eggs if flying that night, otherwise it was bread and jam! And most majestically, the producers managed to get four flying Lancaster Mark 7s out of storage from the RAF for the filming.

Despite all this authenticity, the film still managed to get some parts of the story wrong. Barnes Wallis, memorably played by a grey-haired Michael Redgrave, is presented in classic terms as the eccentric inventor whose brilliant idea it was to bomb the dams but who constantly came up against the brick wall of officialdom. Wallis is portrayed as the bumbling boffin struggling against the grey, unimaginative ‘Men from the Ministry’ – the individual up against the system. This was a stereotype of British films of this time, whether the inventor was R J Mitchell (of Spitfire fame) or Barnes Wallis.

The record shows, however, this was not the case at all. The idea to disable the Ruhr industrial zone by bombing the dams had been discussed by an Air Ministry committee as early as 1938. The problem was how to generate enough explosive power to destroy dams that were well over 100-feet thick at the base and 25-feet thick at the top. A standard 500lb bomb would have had no effect whatsoever on such huge structures.

Barnes Wallis, a much-admired aeronautical engineer, was given a great deal of encouragement to try out his new ideas. He was given permission to use water tanks, to borrow aircraft to drop mock bombs, and, from early 1942, he had access to an actual disused dam, the Nant-y-Gro dam in mid Wales, to blow up. From this he concluded that a bomb of about 6,500lbs dropped against the dam wall and detonated at a depth of 30 feet would generate enough energy to destroy the walls of the dam.

Boffins and bombers

Certainly there were times when Wallis felt frustrated at the slow speed of progress, but never did official interest in his work dry up. Professor Patrick Blackett, the pioneer of operational research, was a keen supporter. He introduced Wallis to Sir Henry Tizard, Scientific Advisor to the Chief of the Air Staff and Britain’s leading aviation scientist of the war, who became another enthusiast for Wallis and his schemes. Neither scientist is portrayed in the film.

At the point at which the proposal to use a bouncing bomb to destroy the dams was taken to the chief of Bomber Command, Arthur Harris, fiction again diverges from fact. The film correctly presents Harris (played brilliantly by Basil Sydney) as a bluff, no-nonsense commander who was sceptical of inventors with new ideas that would risk the lives of his crews. But the film shows Harris coming around to support the idea of the raid and to admire the brilliant inventor behind it.

In reality, Harris remained hostile to the plan throughout, and he called the bouncing bomb ‘the maddest proposition as a weapon that we have yet come across’. He did not like the idea of risking his precious Lancasters and their crews on a precision raid for which the aircraft was not designed, and he saw the whole operation as a major distraction from his policy of destroying the German war economy through area bombing.

Harris jealously guarded Bomber Command’s right to select its own targets. He resisted pressure from the Ministry of Economic Warfare, which wanted to bomb the Ruhr dams, regarding them as a key economic target. Eventually it was only the intervention of the Chief of the Air Staff, Sir Charles Portal, that made the difference. With Churchill’s approval, in February 1943, Portal ordered Harris to carry out the raid, to be codenamed ‘Operation Chastise’. Accordingly Harris told the new commander of 5 Group, Air Vice-Marshal Ralph Cochrane, to form a new squadron to carry out the mission. As in the film, however, it was Harris who chose Wing Commander Guy Gibson to lead the squadron.

Training and technique

From here on, the story increased in pace and drama. There were barely eight weeks for Gibson to train his crews in low-level flying. Meanwhile the designer of the Lancaster, Roy Chadwick and the engineers at A V Roe frantically worked on modifications to the bomb bay so that the Lancasters would be able to carry the bouncing bomb, known by its codename as ‘Upkeep’.

Parts of Upkeep were still shrouded in secrecy when the film was made. In the film the giant bomb is seen as spherical, slung under the Lancaster. In fact it was cylindrical, more like a huge depth charge or mine, 60 inches in length and 50 inches in diameter, containing 6,600lbs of Torpex explosives. In addition, each aircraft contained a giant rotation system that back-spun the bomb at 500rpm, such that when it hit the water it skimmed along it.

The film imagines a scene in which Gibson takes a rare night off and visits a London theatre, where he gets the idea of using two spotlights to focus on the ground to establish the exact height at which the bomb needs to be dropped. This idea in reality came from Ben Lockspeiser, the director of Scientific Research at the Ministry of Aircraft Production, where experiments had already taken place for using spotlights to establish the optimum height to depth charge U-boats.

But the final scenes of the film are as accurate and dramatic as they were for real. Only a few weeks before Operation Chastise, Wallis said the bombs had to be dropped not from 150 feet but from 60 feet. And changes to the design of the bouncing bomb went on until the last minute.

The operation was scheduled for when the spring waters behind the dams would be at their greatest and on a clear moonlight night. That put immense pressure on everyone, engineers, bomb builders, and flight crews, who all had to be ready in a desperately short period. It is a stunning wartime achievement that everything came together in time.

The attack goes in

On the day of the raid the crews were finally told the nature of their targets and were shown terrain models made from aerial photographs by the model-making department of the photo-intelligence centre at RAF Medmenham. For the film, these actual models were used, and Todd tells his crews to ‘get every detail of them in your heads until you know them with your eyes shut’ – just as Gibson would have instructed the real crews.

When the night comes, 16 May 1943, the film faithfully records the story of the mission. At Elstree studios, aircraft interiors had been built that moved on a platform as the actors moved the joystick, creating a primitive sort of flight simulator. Aerial film of the route across Holland and Germany and of flying around the dams was then back-projected on walls outside the aircraft.

The Derwent reservoir and dam in Derbyshire was used for the dam shots. Michael Anderson, the director, was painstaking in creating the effect he wanted, and filming these sequences took several weeks to make them look right. The film showed that it was only after the fifth bomb had been dropped that the Möhne dam finally broke up. And it took three bombs to burst the Eder dam. Though the Scorpe dam was damaged, it did not break.

The end of the film is far from triumphalist. Eight out of nineteen aircraft did not return. The camera lingers in the rooms of the aircrew who never made it back. Gibson does not celebrate but walks quietly off to write letters to the families of the missing. Harris, however, is elated and in congratulating Wallis tells him ‘now you can sell me a pink elephant’.
The reality was quite different. The 40% loss rate on the mission proved to Harris that Lancasters should not be used for precision operations again. Although other aircraft, particularly the Mosquito, were used for precision raids, the real lesson that Harris took from the raid was the need to maintain his policy of area bombing.

The Dam Busters is superbly performed, beautifully shot, edited with tremendous pace, and even most of the special effects still look impressive in a world accustomed to highly sophisticated computer graphics. It stands up well as a fine tribute to the men of 617 Squadron. It is also a great tribute to inventiveness, improvisation, and courage – but with the heroism of the crews played down. It is, in other words, a very British telling of a very British story.