Operation Chastise began a little before half past nine on the evening of Sunday 16 May 1943, when the first of 19 Lancaster bombers took to the air from the grass aerodrome of Scampton in Lincolnshire.


The aircraft belonged to No 617 squadron RAF – a unit that had been brought into being just eight weeks before, for the task on which it now embarked. The squadron was led by Wing Commander Guy Gibson, a veteran of two bomber tours and another tour on night fighters. Gibson was just 24 years old. His crews were armed with Upkeep, the name given to a new and operationally untried water-skipping mine that had been designed by the aeronautical engineer Barnes Wallis. All but two of their targets lay in the Sauerland, a hilly region above the industrial districts of Rhineland-Westphalia, Germany. Since the final years of the 19th century, a number of the Sauerland’s streams had been dammed to create reservoirs. On the night of Sunday 16 May 1943, the RAF was aiming to use Wallis’s mine to release the waters of at least three of them.

Thirty-six hours later, Wallis’s wife wrote to a friend:

“Poor B. didn’t get home till 5 to 12 last night, only 3 hours sleep Saturday, didn’t take his clothes off Sunday, and was awake till 2.30 this morning telling me all about it. And then, poor dear darling Barnes, he woke at 6 feeling absolutely awful: he’d killed so many people.”

The breaching of the Möhne Dam and the Eder Dam across the watershed in Hesse had indeed taken many human lives. But at that point, it was not the deaths in Germany which troubled Wallis; what had kept him awake was the number of aircrew casualties. At the final briefing late on the Sunday afternoon, Wallis had addressed 19 crews. The next day, only 11 of them came back. Fifty-six of the faces into which he had looked justa few hours before were gone, and all but three of them were dead. Among them were the raid’s deputy leader and both the Squadron’s flight commanders.

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Aeronautical engineer Barnes Wallis, photographed in his study
Aeronautical engineer Barnes Wallis, inventor of the Upkeep mine, photographed c1945. Photographs of the Möhne dam before and after the raid hang on his wall. Wallis was deeply troubled by the number of aircrew casualties that the raid caused, writes Richard Morris. (Photo by Central Press/Getty Images)

Operation Chastise posed exceptional hazards. To reach the dams, the crews had to fly in and out of Germany at low level along routes threaded between known flak positions. Such flying required exceptional skill, pinpoint navigation, sustained teamwork and ceaselessconcentration. The perils that awaited even slight lapses or departures from track or height are illustrated by the fact that of the eight aircraft that failed to return, seven were lost on their way to or from the targets. At least three were shot down, having strayed from their routes. Two flew into power lines. Another aircraft returned early after sustaining damage when it touched the sea.

To reach the dams, the crews had to fly in and out of Germany at low level along routes threaded between known flak positions

No 617 Squadron had lost 42 per cent of its fliers in one night. Operation Chastise was thus something graver than the kind of raid that Bomber Command called a “shaky do”. At breakfast, waitresses wept at the sight of dozens of empty places. Later that Monday, a WAAF intelligence officer met listless aircrew wandering outside the Squadron’s hangar. In a nearby crew room she found men sitting in silence, as if in a trance. Several were slumped forward, their heads resting on tables. During the weeks of training, 617’s aircrew had been mocked by Scampton’s other resident squadron for leading easy non-combatant lives. There was no joking now.

For many who survived, then, their first reaction was that they had escaped from a tragedy and were lucky to be alive. A few hours later, with a kind of emotional whiplash, the same men were presented as instruments of a great victory and proclaimed as Allied heroes.

First news of the attack was given by the BBC that Monday evening. It was a vivid, unexpected, gripping story, and the next morning, as 617’s aircrew boarded buses and trains for a week’s leave, it filled the front pages of every national newspaper. “RAF BLOWS UP THREE KEY DAMS IN GERMANY,” ran the headline in The Daily Telegraph, which not for the last time overstated what had actually happened. “FLOODS POURING THROUGH THE RUHR,” said the Daily Mail, which described “railway bridges, power stations, factories, whole villages, and built up areas . . . being swept away”. “HUNS GET A FLOOD BLITZ,” sang the Mirror. Three days later the Mail told of a “HUNDRED MILE WAVE”, while a News Chronicle headline said: “MOHNE FLOODS HAVE SWEPT 60 MILES BEYOND DAM”.On 21 May, The Manchester Guardian reported on growing electricity shortages in parts of Germany.

The story went around the world. The Air Ministry distributed reconnaissance photographs of the broken dams and floods to the neutral and Allied press.Leaflets bearing before-and-after photographs of the dams were dropped over occupied countries.

First news of the attack was given by the BBC that Monday evening. It was a vivid, unexpected, gripping story

The raid stayed in the news for months and as time passed, wishful thinking about its effects increased. At the end of May, Reuters’ correspondent in Stockholm cabled that estimated casualties from the Möhne and Eder combined were 70,000. The Scotsman quoted neutral sources to the effect that more than 50 towns had been flooded; 4,000 people killed and 120,000 rendered homeless. Several newspapers carried stories about civil disorder resulting from a supposed breakdown of services and authority. Early in August, The Daily Telegraph reported that a quarter of a million industrial workers had been traumatised by a form of psychological shock.

The breached Möhne dam, following the Dambusters raid in 1943
The breached Möhne dam, following the raid by 617 Squadron in May 1943. The breach of this dam and the Eder dam across the watershed in Hesse resulted in many lost lives. (Photo by Keystone-France/Gamma-Rapho via Getty Images)

Some of the stories sprang from rumours planted by the Allies in the hope that they would demoralise Germany’s home front. One of these claimed that drinking water had been contaminated, leading to the spread of typhoid and intestinal diseases. In fact, no help was needed in generating rumours in Germany. Stories multiplied within hours and, for a time, the Propaganda Ministry in Berlin was uncertain how best to react to them. This was partly because of the very large numbers of people who witnessed the damage first-hand. What they saw could not be reconciled with official claims that the attacking force had been “weak”and that the dams had merely been “damaged”and, when anxious relatives rang them, a narrative of widespread damage soon circulated throughout Germany.

With it went a paradox: if, as German radio said, the force that had caused this havoc was feeble and had dropped only a “small number of bombs”, did this not emphasise the potency of Bomber Command? Attempts to blame Jewry for the bombing backfired for similar reasons. Party officials pointed out to the Ministry that, since the raid had been a clear tactical success, Germany’s inability to destroy similar targets in Britain could hardly be explained by a failure to call upon “Jewish resourcefulness”. Although the names of the broken dams were withheld, unauthorised photography banned and foreign journalists excluded from the flooded areas, it was widely believed inside Germany that 30,000 had been killed.

The authorities tried to counter the rumours by publishing official figures of their own. On 19 May, the German News Agency reported 711 victims of the Möhnekatastrophe. Of these, 370 were German and 341 wereprisoners of war. A subsequent district-by-district survey gave the combined total death toll as 1,348, while several weeks later the administrative division of Gau Westfalen-Süd told the press that 1,579 had perished, of whom 1,020 had been forced labourers and prisoners of war. Another 70 lives had been taken by the waters of the Eder, it claimed.

How much damage was caused by the Dambusters raid?

Even today there is no agreed final figure for the fatalities. Some victims were never found, and poor record-keeping at a forced labour camp below the Möhne left the authorities unsure how many had been there in the first place. The flood anonymised some victims by battering them so badly that they could not be identified. Infants sucked from their cradles were borne for such distances that no one knew where they came from. More than 160 of the nameless dead were photographed, each with a number chalked on a board placed next to the bruised face.

Then there were the livestock casualties: animals in fields, byres and stables had no means of escape and thus perished in thousands. Downstream of the Eder dam, more than 400 cattle drowned, along with 700 pigs and 56 horses. Deaths of cattle, horses and pigs below the Möhne exceeded 5,000. Survivors of the flood recollect their calls of panic as they were swept away. With them perished thousands of smaller animals like goats and sheep. In the Möhne valley alone nearly 12 square miles of farmland were spoiled. Other kinds of environmental damage – like deposits of pollutant fuels, heavy metals and sewage sludge smeared across land – went unrecorded at the time and only now are coming to be recognised.

Operation Chastise still looms large in public memory. In Germany it is commemorated quietly and reverently as the disaster it was. In Britain the raid has acquired a legendary status, witnessed in the torrent of new books, articles and gala screening of the 1955 film The Dam Busters in the Royal Albert Hall to mark the raid’s 75th anniversary in 2018. It is fair to ask why an event with such heart-breaking consequences for almost all concerned should still stir fulsome national feelings.

The 1955 film 'The Dam Busters' depicted a version of events which endures in public memory, says Richard Morris. (Photo by: Universal History Archive/UIG via Getty images)
The 1955 film 'The Dam Busters' depicted a version of events which endures in public memory, says Richard Morris. (Photo by: Universal History Archive/UIG via Getty images)

So was the Dambusters raid a success? It is not as if Chastise succeeded on its own terms. For all the raid’s audacity and courage; the technical brilliance behind it; and despite the widespread destruction and adverse repercussions for the German war economy that it certainly caused, it did not bring about the long-term crisis for which planners in the Air Ministry and Ministry of Economic Warfare had hoped. There were two main reasons for this: the attack had focused on the wrong combination of dams; and it was planned as a stand-alone operation by a small force rather than as part of a sustained campaign by a larger one.

To bring about a systemic economic failure the RAF needed simultaneously to destroy a number of dams – and in particular the Sorpe as well as the destroyed Möhne – and the pumping systems that linked them, and then re-attack them at intervals to prevent repair.

Was the Dambusters raid a success? It is not as if Chastise succeeded on its own terms

The speed and resourcefulness with which the broken dams and pumping stations were repaired, plusthe diversion of large military assets to defend them for the rest of the war, reflects the depth of anxiety in several Reich Ministries about this risk. It was also reflected in the nervousness of Oberkommando der Wermacht (OKW, High Command of the Wermacht) on the raid’s first anniversary, when Sauerland reservoirs again were full and extra defences broughtin to defend them against a repeat attack. OKW did not know that only 23 Upkeep-carrying Lancasters had been built the year before and that, by May 1944 (following losses on operations and flying accidents), only 11 were now available. Hence, even if RAF planners had wished to mount a sustained drive against Germany’s water industry, the specialised force needed to do it was insufficient.

Barnes Wallis (left) with British actor Michael Redgrave
Barnes Wallis (left) with British actor Michael Redgrave who plays Wallis in the 1955 film 'The Dam Busters'. (Photo by Evening Standard/Getty Images)

Full details of how Upkeep worked were not released until 1962, but the fact that it bounced across water became known in 1955 when cinemagoers were given first glimpses of Wallis’s weapons in Michael Anderson’s film The Dam Busters. Audiences took to Michael Redgrave’s portrayal of Wallis as a softly-spoken, slightly abstracted genius. Redgrave spoke words written by RC Sherriff, whose screenplay depicted Wallis as meek yet determined, neither downcast by snags and disappointments nor resentful of others’ scepticism. The souvenir programme for the premiere said that although experts had “scoffed” at his ideas, Wallis’s faith had “never wavered” as he tramped from one government department to another seeking support for his “impossible” brainchild. In fact, while Wallis’s projects often met opposition –and the bouncing bomb was no exception –it has long been realised that the weapon could not have emerged without substantial official backing. It is also clear that far from being unwavering during preparations for the attack, Wallis was wracked with worry. The film’s version of events nonetheless endures and, with it, a narrative of daring imagination versus dull officialdom leading to an outstanding feat of arms that has gripped the nation ever since.


Richard Morris is Emeritus Professor at the University of Huddersfield, specialising in battlefield archaeology and aviation history. He is completing a new biography of Barnes Wallis