21 April 2021
Joshua Bilton explores Operation Chastise, the raid on the Möhne, Eder and Sorpe dams.
For the residence of Scampton, Lincolnshire, the night of 16 May 1943 was uneventful. Families, some without brothers and fathers who away serving overseas, settled down to rest; many had a long week ahead. Lights were slowly extinguished, as one by one the villagers made their way to bed. Two miles away the scene was somewhat different. The still night air was rent with the sound of Rolls-Royce Merlin engines being started. Crews scrambled to positions aboard one of 19 modified Avro Lancasters. Last minute checks were made, the chocks removed and the first of the heavy bombers taxied across the runway taking off into the dark, but cloudless night. Their target was the Ruhr Valley, and the dams of Möhne, Eder and Sorpe.
The British Air Ministry, even before World War II started, had identified numerous strategic targets in Germany. These included oil, which was considered very vulnerable, gas and water. Of the latter, it was German’s heavily industrialised Ruhr valley and especially its dams that were judged to be of great importance. In addition to providing hydroelectric power and pure water, for making steel, the dams also supplied drinking water to the region and water to the inland waterways; an integral part of the German transport system.
Left: The Eder dam, as it was before the war. The two buildings (right of the camera) are the transformer station and the engine house respectively
A number of dams were identified including the Möhne, Eder and Sorpe. The former contained one of the largest reservoirs in Germany, while the latter fed the inland water system. It was anticipated that if struck, the resultant fallout would not only devastate the surrounding countryside, but also destroy factories and villages.
By 1943 Germany had been defeated in North Africa, the tide had turned in the Soviet Union and the air war was in full swing with Bomber Command raining high explosives onto targets all over Europe. The time had come to start planning for a raid on the dams and a strike at the industrial heartland of the enemy.
However, if the mission was to be carried off the Air Ministry required a special kind of bomb. The dams were guarded by torpedo nets in the water and were made of steel re-enforced concrete. At that time the RAF was not in possession of a bomb capable of delivering an explosion powerful enough to fracture the dams. The War Office had considered the idea and even commissioned research, but was yet to conduct trials. The closest thing available was a prototype depth-charger designed by Barnes Wallis, assistant chief designer at Vickers. Wallis had first conceived of the idea in 1942, while skipping glass marbles across a tank filled with water. Like marbles, the bomb (essentially an oil-drum), was designed to skip across water before sinking to explode.
Right: Sir Barnes Wallis, inventor of the bouncing bomb (codenamed Upkeep)
It was not Wallis, however, but Professor Patrick Blackett, scientific advisor to the Admiralty, who saw the bomb as a weapon of the RAF. Indeed, Wallis had considered the depth-charger as, ‘essentially a weapon for the Fleet Air Arm.’ A meeting was subsequently arranged between Wallis and Henry Tizard, scientific advisor to the Ministry of Aircraft Production (MAP). Upon receiving Wallis the latter was suitably impressed, recommending further testing, post haste.
Bomb testing (Nant-y-Gro, Chesil Beach and Reculver)
The first trials were carried out on 24 July 1942. They were conducted at the redundant, Nant-y-Gro dam, Wales. A mine, containing 279lb of explosive, was detonated remotely blowing a huge central section of the dam away.
The operation was considered spectacularly successful. Secondary trials thus followed suit, the first of which was carried out at Chesil Beach in December 1942, while the second at Reculver in April 1943. On both occasions, each mine, now codenamed Upkeep (or the Vickers Type 464), were filled with inert material and dropped from a modified Avro Lancaster. This was the first time such an experiment had been undertaken.
Left: After the spectacularly successful demonstration at Nant-y-Gro, Wales, the first trials were conducted at Chesil Beach in December 1942. Wallis is photographed to the left of the group; hatless and with arms outstretched
Of the four principal heavy bombers in production by 1942, the Avro Lancaster was the most suited to the task of carrying Upkeep. Not only was it the largest of any RAF bomber, but also capable of carrying the greatest single payload. The Handley Page Hampden, though in possession of an internal load of 13,000lbs, was required to divide this between three separate compartments, thus limiting the size of any ordnance.
The aircraft had undergone extensive modification. This included removing the mid-upper gun turret and bomb bay doors, attaching two callipers to hold Upkeep in place, and a single belt driven by a Jassey hydraulic motor. The latter, was to set the bomb spinning. Indeed, it had been realised early on that for Upkeep to skim, like a stone, across the water, backspin was required.
Left: Specially modified Lancasters were designed to carry Upkeep. The bomb was held in place by a pair of calipers (or carrying arms), while backspin was imparted via a belt driven by a hydraulic motor
For a mission of this importance a highly trained and specialist unit was required. On 24 March 1943, Squadron X (part of No. 5 Group RAF) was formed, with Wing Commander Guy Gibson its commanding officer. The initial formation was comprised of 21 separate crews. The majority of whom were friends of Gibson, including Flight Lieutenant’s John Hopgood, Harold “Micky” Martin and David Maltby.
The crews trained almost religiously, mounting dummy attacks on three dams located within England: the Abberton, Derwent and Eyebrook reservoirs. Aircrew, flying in the modified Avro Lancaster Mk III, practiced approaching the target and releasing Upkeep. The mission was classified so at the time the men were certain they were preparing to attack the Tirpitz.
In an effort to maximise night flying, two aircraft were modified. The cockpits were covered in blue celluloid, while the pilots and bomb aimers were ordered to wear goggles with amber-tinted lenses.
Shortly after 6pm on Sunday, 16 May 1943, the members of 617 Squadron assembled in the large meeting room of the Flight Sergeant’s mess at RAF Scampton. Once the men were seated, Gibson, standing at the front, announced that the squadron was, “to attack the greatest dams of Germany: the Möhne, Eder and Sorpe.” Of the 19 aircraft, nine were to attack the first two targets, while a further 10, flying in two separate waves (formations No. 2 and 3), were to strike the latter.
Following Gibson came Wallis, who, after a brief introduction, expounded upon the use of Upkeep and its role in the forthcoming mission. In the case of the Möhne and Eder, it was to be employed as a conventional bouncing bomb, while for the Sorpe it was to be dropped from directly above; a consequence of the surrounding typography. At 7:30pm, the briefing was adjourned. Gibson reiterating, as the men departed for an early dinner, that no crew was to return carrying Upkeep.
Left: The plan, as conceived by Barnes Wallis. The drawing details how the depth-charger was to skim the water, bouncing across the torpedo nets and to eventually explode against the base of the dam
Formation No. 2 took off at 9.28pm. Their flight was much longer than that of No. 1, and required heading north and entering Europe over the island of Vlieland, crossing the Ijsselmeer (an inland bay in the central Netherlands), before flying south towards the Möhne Reservoir and onwards to the Sorpe dam.
Some 11 minutes later, formation No. 1 followed suited, the nine aircraft setting off in groups of three, with a 10-minute interval between each. Their route was slightly different; they were to strike Europe between Walcheren and Schouwen, fly across Holland and into Germany, curve around the Ruhr defences, before turning south towards the Möhne and Eder.
Right: A map of the three dams: the Möhne, Eder and Sorpe
The last of the crews took off at 12.09am on Sunday, 17 May 1943. Flown by the crews who did not reach the high standards of accuracy in practice, formation No. 3 was destined for the Sorpe, as it was felt that, ‘the attack method against this dam was simpler.’ They were several hours behind their counterparts in formations No. 1 and 2, and were following the longer route north.
The three formations flew low. At just under 100ft, they were below the level of radar. So determined were the men to avoid detection that one aircraft (O-Orange) flew the length of a forest’s firebreak, less than 40ft from the ground.
A number of casualties were sustained early on: two, as a result of flak over the island of Vlieland, three as consequence of low flying. Indeed, an eyewitness account (that of Roswitha Reiming), details how one Lancaster (B-Baker) struck an electrical pylon, burst into flames and subsequently landed near Marbeck. At this point, ammunition from the six .303 Browning machine guns on-board began to explode. Two minutes later, Upkeep erupted enveloping the aircraft and shattering the glass of every window in a local farmhouse.
Left: Perhaps the most feared of all anti-aircraft guns: the dreaded 8.8 cm Flak 36. More commonly referred to as the 88mm
The Möhne dam
At around 12.15am on the morning of 17 May 1943, the first of nine aircraft reached the Möhne damn. G-George was followed by M-Mother and P-Peter (Popsie). "Stand-by, chaps," radioed Gibson (speaking as the pilot of G-George), “I’m going to look the place over.”
Despite the hail of gunfire, Gibson flew low crossing the dam at its centre. Satisfied he banked, turning back towards the orbiting aircraft. On his return, he was greeted with the arrival of Squadron Leader Henry Young, Flight Lieutenant David Maltby and David Shannon. His initial three had increased to six; just three more and they were a set.
"Well, boys,” said Gibson speaking to his crew. “I suppose we had better get the ball rolling.” Over the VHF (Very High Frequency) radio he announced, “I am going to attack. Stand by to come into attack in your order when I tell you.”
Doing exactly as he had practiced during training Gibson approached the target. Upkeep was released at 500 rpm and a speed of 230 mph. It bounced three times, and came to rest just short of the dam, exploding in a ‘huge spout of water.’
Next, came 21-year old, Flight Lieutenant John Vere ‘Hoppy’ Hopgood (a late arrival). Hoppy’s plane had been hit by flak an hour before reaching the dam, damaging the plane and wounding most of the crew but he pressed on regardless. The plane was streaming oil smoke behind from the port outer Merlin engine. The front gunner, Gregory, was either dead or incapacitated; Minchin, the wireless operator, had been hit by cannon fire in the leg, almost severing it; and Burcher, the rear gunner, was hit in the stomach and groin. Flight Engineer Brennan was trying to stem the flow from Hoppy’s own head wound, and commented, “Christ, look at the blood.”
Typical of these resolute young men, Hopgood simply replied, “I’m okay. Just carry on and don’t worry.”
Hopgood got his Lancaster into position, despite being hammered with tracer fire. The bomb was released just as 20mm cannon hit the starboard wing engines and fuel cells, catching fire. The plane lurched towards the water but Hopgood fought to get it over the dam, just as his Upkeep bomb skipped over the protective nets and then, agonisingly, over the dam parapet wall itself. It sailed over the drop and hit an electric power station, completely destroying it. Hopgood ordered the crew to bail out and open up the throttle, straining to get the last bit of altitude for the stricken bomber. Burcher clipped the badly wounded Minchin into his parachute and shoved him out, but his parachute failed to deploy and he fell to his death. Hoppy shouted back to the rear gunner, “Get out you damn fool.”
Burcher and Fraser opened their parachutes inside the aircraft, Fraser jumping clear but there was a sudden explosion, throwing Burcher out and onto the tailplane, breaking his back. Miraculously both of them made it to the ground alive, spending the rest of the war as PoWs. As they fell the burning wing of the Lancaster disintegrated and the bomber fell, uncontrollable into the ground, killing John Hopgood and the remaining crew.
Back above the dam, Gibson performed a half-circle rotation. G-George levelled out flying parallel, and just abreast of P-Peter, drawing AA fire away as the next Lancaster started its bombing run. Flight Lieutenant Harold Martin released his bomb but, for the second time that night, it exploded prematurely, just short of the target. Would the men 617 Squadron complete their mission?
Left: In a still from the film The Dam Busters (1955), starring Michael Redgrave and Richard Todd, the bomb-aimer lines up his bombsight and prepares to discharge Upkeep
Finally, in came A-Apple and J-Johnny. The first of the two bombs struck the water, bounced and came to rest at the base of the Möhne before exploding, exactly as planned. The second Upkeep followed roughly the same path, also reaching the dam wall, sinking and exploding with devastating force. As the surviving Lancasters flew on, tracer fire reaching after them, the dam wall crumbled and, at 12.56am a torrent of million of tons of water poured through gap and into the valley below.
Back at Scampton, the news that the Möhne had been breached was received with much enthusiasm and applause. Air Marshal Arthur Harris, once sceptic of the plan, smiled broadly. Grasping the scientist’s hand he remarked, “Wallis, I didn’t believe a word you said, when you came to see me. But now you could sell me a pink elephant.”
Right: A photograph taken from atop the Möhne dam, demonstrates just how significant the breach was on Sunday, 17 May 1943
The other dams
Despite a lack of VHF and subsequent compass problems, Flight Lieutenant Joe McCarthy had found the Sorpe reservoir. Of the three, the earthen dam was the hardest to attack. The surrounding typography required that Upkeep be dropped from directly above. Flying the axis of the dam, McCarthy bombed once, and was followed by Squadron Leader Kenneth Brown.
Yet, both were unsuccessful; the Sorpe remained intact despite minor damage to its crest. With nothing left to give the men turned for home. Their mission had not gone according to plan.
Upon breaching the Möhne, Gibson and the remaining crews turned south towards their secondary target. Their arrival, at the Eder dam, coincided with an early morning mist, and it took several (tantalising) minutes to locate the target. Squadron Leader Henry Maudsley was the first to attack. Skimming the water he approached the reservoir releasing Upkeep. The bomb struck the parapet of the dam, exploding prematurely, the blast catching the Avro Lancaster as it sallied overhead.
Flight Lieutenant David Shannon followed suited, his attack causing a crack in the dam, which was ultimately exploited by Flight Lieutenant Les Knight. At 1.54am on Sunday, 17 May 1943 the code word, (D-I-N-G-H-Y) was radioed to base. Eder breached and ‘mission complete.’
Left: Though water continues to pour through the breach, it is beginning to slow. It will be months, however, before the Eder dam is operational
When the Möhne dam was destroyed it resulted in 330 million tons of water pouring into the western Ruhr area. A few mines were flooded, 11 small factories and 92 were destroyed with a further 114 factories and 971 houses being damaged. Some 25 roads, railways and bridges were swept away as the flood water spread out to cover 50 miles from the dam itself. The biggest impact was on farmland, with many square miles being rendered unusable until into the 1950s.
On top of this, it is estimated that 1,200-1,600 people were killed, as a result of the floods, several hundred of who were foreign labourers (from France and Belgium), as well as a number of Russian PoWs (Prisoners of War).
Right: Residents, stare in amazement, at the rising waters: the destruction of the dams at Möhne and Edersee devastated not only arable land and local industry, but also family homes
Furthermore, German sources estimated that coal production dropped by 400,000 tons in May 1943 and two hydro electric power stations that supplied armament factories were destroyed and others damaged. It resulted in no power in the area for two weeks. In the words of Albert Speer (Hitler’s chief architect), ‘it was a disaster for us for a number of months.’
Left: The force of the water was so powerful that railway lines were ripped from their foundations
However, the disruption could have been much greater but Bomber Command failed to follow up with subsequent sorties. The addition of flak batteries, nets and wooden deflectors to the area were a formidable defence, but the RAF had faced all these things before and precise bombing was not required to hinder the repair work. Still, it took until 27 June 1943 before full water was restored, along with the electrical grid. It was also four months before the Möhne was repaired, in September 1943, and became operational again.
What is rarely considered is the strategic effect. The considerable amount of labour and resources needed to repair the dams, factories, mines and railways could not be used in other ways, such as supporting the war in the east or in bolstering the Atlantic Wall defences against the Allied invasion that was to come the following year.
Above: The town of Hattingen, Ruhr Valley: the water, even by the afternoon of 18 May, is yet to subside
Of the 133 members of Bomber Command who flew in the raid, 53 were killed and three were taken prisoner. The surviving crews were hailed as heroes and Guy Gibson received the Victoria Cross. 617 Squadron became established as a specialised, precision bombing outfit – see the feature on page 82 to discover more. It was a huge propaganda victory as well, showing the Britain could strike at the heart of the German war machine. As Dr John Sweetman remarked, “Exploitation of success in the form of publicity is, and always has been, a legitimate tool in war.”
Above: Wing Commander Guy Gibson (front) and the crew of AJ-G. The purple medal ribbon, below the aircrew brevet (officially known as an aircrew badge) on Gibson’s tunic, is that of the Victoria Cross (VC)
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