The Möhne dam the day following the attacks.


Wing Commander Guy Gibson on parade during the King’s visit of May 27, 1943.

The Bouncing Bomb

Operation Chastise, the Dambuster raid against the Möhne, Eder, Sorpe and Ennepe Dams in Germany’s Ruhr industrial region, was only made possible by the ground-breaking work of the aviation designer, Dr Barnes Wallis.

Barnes Neville Wallis was born on 26 September 1887 in Ripley, Derbyshire, and was educated at the prestigious Christ’s Hospital boarding school in Horsham, West Sussex. He rose to prominence with his pioneering geodetic basket-weave method of airframe construction, which was adopted for the R100 airship in 1930 while he was working for Vickers-Armstrongs’ Airship Guarantee Company in Hull. Pierson recognised Wallis’ obvious talents and encouraged him to move into aircraft design. Wallis subsequently worked closely with Pierson on the development of the Vickers Wellesley and Vickers Wellington bombers, both of which used his geodetic design for the construction of their wings and fuselage.

It was while Wallis was working alongside Pierson that Vickers allowed him sufficient freedom to explore other ideas and he was able to work on the development of his bouncing bomb. In April 1942 Wallis wrote his now infamous paper Spherical Bomb – Surface Torpedo, in which he first put forward his idea for a bomb that could attack shipping by bouncing across the surface of water. Initially, his idea was that the bomb should be used to attack German capital ships, including the Tirpitz, which was hidden away deep inside a Norwegian fjord. His intention was that the bomb would bounce across the water of the fjord and so avoid the torpedo nets that protected her, nets that made a conventional attack almost impossible. Not surprisingly therefore, it was the Royal Navy that first championed the proposal and encouraged Wallis to pursue it further. It was the support from the Admiralty that led to a series of trials at Chesil Beach in Dorset in January 1943, tests which eventually proved the bomb’s viability. It is widely regarded that without the Admiralty’s support the bouncing bomb may not have got off the drawing board.

It was at this time that a flurry of political wrangling took place behind the scenes of the Air Staff which threatened to put an end to the bouncing bomb. Air Vice-Marshal Francis Linnell at the Ministry of Aircraft Production was known to be sceptical about the bomb and was concerned that the time Wallis was spending on developing it would distract him from vital work needed to get the Vickers Windsor heavy-bomber into production. On 12 February 1943 Wallis learnt that Linnell was planning to request that the bouncing bomb project be cancelled. Determined to see it through Wallis wrote to a friend at the Air Ministry, Group Captain Fred Winterbottom, to see what could be done to save the bomb. His seemingly desperate letter included the phrase “help, oh help” written across the bottom.

Winterbottom wrote to Air Vice-Marshal Francis Inglis, a senior officer on the Air Staff and suggested, falsely, that the Prime Minister was interested in the bomb, that the Royal Navy were likely to move the development of the bomb forward without the Royal Air Force and implied that the Chief of the Air Staff, Air Chief Marshal Portal had not been fully briefed on the situation.

Learning of Winterbottom’s letter, Air Vice-Marshal Linnell wrote to Arthur Harris, Air Officer Commanding-in-Chief of RAF Bomber Command and warned him that a number of his precious Lancaster bombers may be requisitioned for the bouncing bomb. Furious at the potential loss of the aircraft Harris wrote a stern letter to Air Chief Marshal Portal on 18 February 1943, which suggested that he thought the weapon only existed in the imagination of those who had proposed it and that “Highball is just about the maddest proposition as any that have yet come across – and that is saying something.”

Linnell then contacted Charles Craven, the chairman of Vickers and warned him that Wallis’ actions in pressing for the bouncing bomb were putting his company’s commercial interests at risk. Wallis was put under pressure by Craven to drop the project, but, as was typical of his stubborn nature, he chose instead to resign from Vickers.

Winterbottom’s letter to Inglis, however, had remarkably managed to turn the situation around. On 19 February 1943, the day after Harris had written his letter, Inglis had ensured that Portal had been fully briefed and that he was shown the footage of the trials at Chesil Beach. As a result of this briefing Portal wrote to Harris saying: “As you know I have the greatest respect for your opinion on all technical and operational matters and I agree with you that it is quite possible that the Highball and Upkeep projects may come to nothing. Nevertheless I do not feel inclined to refuse Air Staff interest in these weapons since I think the whole conception is far simpler than that of the Johnny Walker or the Toraplane, and we know that the full size mock-up of Highball does what is claimed for it (unless the cinema lies!)” Portal then ordered an astonished Linnell to approve the bouncing bomb project.

On 26 February 1943 Linnell briefed Wallis on the proposal to attack on the dams and stated that the raid would have to take place by the full-moon in May of that year. This gave Wallis just two months to complete his development, during which time Bomber Command was required to establish and train a special squadron to undertake the mission. The new 617 Squadron was established in record time and was based at RAF Scampton in Lincolnshire, with Wing Commander Guy Gibson appointed as its commander. It has been suggested that Gibson handpicked the squadron from the ranks of former colleagues, choosing the most experienced crews. In fact Gibson had only previously known four of the pilots who joined the squadron. As for them being the most experienced, rear gunner Canadian Grant MacDonald had flown just four missions before he joined the squadron.

The Raid

On the night of 16 May 1943 nineteen Lancaster Mk III bombers from 617 Squadron, armed with Upkeep bouncing bombs, took-off from RAF Scampton to attack the Möhne, Eder, Sorpe and Ennepe Dams in Germany’s Ruhr and Eder valleys. To compensate for the size and weight of the bomb, each aircraft was specially modified, which included removing most of the internal armour and the bomb-bay doors.

The aircraft were divided into three formations. The first consisted of nine aircraft and was assigned to the Möhne Dam, with orders to then attack the Eder Dam if they had any bombs remaining. The second formation consisted of a further five aircraft and was set the task of attacking the Sorpe Dam. The third formation was made up of another five aircraft and was intended as a reserve force that took-off two hours after the first two formations had departed. The second formation was the first to take-off and left RAF Scampton at 9.28pm on 16 May. They took a longer northern route to the dams, whilst the first formation, which took off from 9.39pm in groups of three at ten minute intervals, was assigned the shorter southern route. The third formation began to take-off early the following morning at 0.09am.

Gibson led the first formation and was the first to attack the Möhne Dam. Flight Lieutenant John Hopgood made the second run, but was hit by flak as he approached the dam and was then caught by the blast of his own bomb. Gibson flew across his flight-path in an attempt to draw away the enemy’s fire, but Hopgood crashed shortly after. Two of Hopgood’s crew managed to survive. Flight Lieutenant Harold Martin then made the next run and successfully attacked the dam, followed by Squadron Leader Henry Young and Flight Lieutenant David Maltby. The dam was eventually breached and Gibson led the remainder of the first formation on to the Eder Dam, with Lancasters piloted by Squadron Leader Henry Young, Flight Lieutenant Dave Shannon, Squadron Leader Henry Maudslay and Flying Officer Les Knight.

Once over the Eder Valley the Lancasters encountered thick fog, which made lining up the next attack more difficult. Shannon made six runs at the target before he stepped aside and let Maudslay make an attempt. Maudslay dropped his bomb in the attack, but it clipped the top of the dam and the explosion damaged his aircraft. Shannon then made his next attempt, which successfully exploded behind the dam. Knight then made his next run and successfully exploded his bomb against the dam, which finally was sufficient to cause a breach.

Flight Lieutenant Joe McCarthy from the second formation, with Flight Sergeant Ken Brown and Flight Sergeant Cyril Anderson from the third formation, reached the Sorpe Dam. Unlike the other dams, which were made of concrete, the Sorpe was of earthen construction and was expected to be much harder to breach. For these attacks the Lancasters were to approach along the length of the dam, rather than at right angles, and the Upkeep bomb was not spun in the aircraft before it was dropped. McCarthy made ten attempts at his run before he dropped his bomb. He managed a direct hit but caused very little damage. Brown made his attack, but also failed to damage the dam. Anderson abandoned his run due to the dense fog. The remaining Lancasters were then ordered on to other targets before turning for home. Pilot Officer Warner Ottley was shot down before he could reach the Lister Dam and although Flight Sergeant Bill Townsend managed to launch an attack on the Ennepe Dam his bomb did not cause any damage.

The surviving aircraft started arrive back at RAF Scampton from 3.11am. Gibson returned at 4.15am and Townsend was the last to return home, reaching the air base at 6.15am.

Of the nineteen Lancasters that left that night, eight did not make it back. The aircraft were required to fly at a perilous height of one-hundred feet for most of the journey in order to avoid enemy radar detection. As a result two of the Lancasters collided with power cables and were lost before reaching their targets, two aircraft were shot down over the Netherlands before they could reach their target and a third was shot down over Germany before it reached the dams. After the attack two Lancasters were shot down over Germany and one was shot down over the Netherlands. Fifty-three of the one-hundred and thirty-three aircrew who had left the previous evening were killed on the raid, of which thirteen were Canadian and two were Australian. There were three survivors taken prisoner-of-war, two were from Hopgood’s aircraft and the third was from Ottley’s.

A total of thirty-four air crew were recognised for their contribution to the raid and received decorations at a ceremony held at Buckingham Palace on 22 June 1943. Gibson was awarded the Victoria Cross. In addition, five airmen received Distinguished Service Orders, ten Distinguished Flying Crosses and four bars, two Conspicuous Gallantry Medals and eleven Distinguished Flying Medals and one bar.

Wallis was shocked by the loss of life amongst the aircrew of 617 Squadron, who he had got to know during the weeks prior to the raid. When the Royal Commission awarded him £10,000 for his work during the war he donated it to his old school, Christ’s Hospital, to establish the RAF Foundationers’ Trust that could pay for children of airmen killed or injured in action to study at the school.

Wallis and his wife Molly had four children and their daughter Mary married Harry Stopes-Roe, the son of the women’s rights campaigner Marie Stopes and Humphrey Verdon-Roe, co-founder of AV Roe and Company Limited, the aircraft manufacturer that designed and built the Lancaster bomber.

A special memorial to those who took part in Operation Chastise was erected at Woodhall Spa, near to RAF Scampton. In 2008 a statue of Barnes Wallis was erected near Reculver in Herne Bay, Kent, where the Upkeep bomb was tested.

A memorial was erected in Neheim, four miles from the Möhne Dam, in memory of the German dead. Figures have since suggested that in Germany the raid cost the lives of 1,294 people, of which 749 were believed to have been French, Belgian, Dutch and Ukrainian prisoners of war and labourers.

Examples of various bouncing bomb prototypes can be found at museums around the UK, including the Aeronautical Museum at Brenzett, Romney Marsh, the Brooklands Museum in Weybridge, Dover Castle in Kent, the Imperial War Museum at Duxford in Cambridgeshire and the Spitfire and Hurricane Memorial Museum at RAF Manston in Kent.


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