“Operation Chastise – No 617 Squadron, The Dambusters” Dudley Hooley, Director, Tangmere Military Aviation Museum

The Background
In the 1930s Adolf Hitler came to power in a politically fragmented and bankrupt Germany. During the following years it became apparent that Hitler was rebuilding Germany following the First World War and had military ambitions which made the country a threat to those about them and their allies. Most of the central European countries were catalysed (to varying degrees) by these developments and Great Britain commenced a late, but timely, re-armament program.
It is fair to say that the operation to destroy the German dams in the Ruhr began on Tuesday July 26th 1938 at a meeting chaired by Air Vice Marshal W. Sholto Douglas, Assistant Chief of the Air Staff. This was a meeting of the RAF Bombing Committee and one of the main items on the agenda was to bring to the meetings attention a possible weak point in the German industrial economy. This potential weakness was a number of reservoirs that supplied power and water to manufacturing industries which in the time of conflict would be turned over to war manufacture. The object of the meeting was to enquire into the extent to which effective air action against the dams of the reservoirs would be possible. Bombing Committee paper number 16 was circulated and this document described the types of construction and siting of the dams, along with notes on the potential damage that could be caused by a number of the air dropped weapons then available.
Squadron Leader C G Burge, representing the Air Targets Sub-Committee of Aerial Intelligence, reported that the amount of water consumed in the whole of Germany was only three times that of the Ruhr and that the bulk of it was obtained from one large reservoir contained by a single large dam, known as the Möhne Dam. He added that there were also four or five other reservoirs in Germany which fed the inland waterways, the destruction of which was likely to leave the waterways high and dry, which would severely affect the German transportation system.
It also seemed reasonable to believe that the damage caused would be extremely difficult to put right.
At this stage all discussion was about bombing the dams with existing weapons. The largest of these was then the 500lb semi-armour piercing bomb designed to be used against ships. When dropped from a sufficient height, it had penetrated in tests 5ft into concrete and the thickness of a dam at a depth of 40ft was estimated to be approximately 12ft. It was felt that, if a bomb could be driven into the wall to a depth of 5ft, the remaining 7ft should be severely damaged or breached but no discussion was given to special weapons. It was recognised during the meeting that any bomb would be far more effective when placed on the wet side of the dam, rather than the dry side. The possible use of torpedoes was also discussed. The final outcome of the meeting was that at the present time it was considered that the attack should be directed primarily against the high water side of the dam. Attack against the lower side was considered less likely to be effective unless a bomb could be devised that which would develop sufficient striking velocity to achieve the necessary amount of damage at low altitude.
The seed had been sown and then matters rested for three years. In essence however the basis of Operation Chastise had been established, namely:
1. that the destruction of the Möhne dam would remove a large percentage of the water required by the Ruhr Valley industries to produce war materials along with a substantial amount of hydro-electricity;
2. that the destruction of the smaller Ruhr dams would cause some loss of electrical power and great disruption to the German inland waterway system upon which a great proportion of German industry and war making capability depended;
3. an additional fringe benefit would be the damage caused to industry and infrastructure by the release of large amounts of water from these reservoirs.
Dr Barnes Wallis
Barnes Wallis was born in 1887 and schooled at Christ’s Hospital and Haberdashers’ Aske’s schools in London. Unable to afford university, he started an indentured apprenticeship at the Thames Engineering Works at Blackheath. In 1908 he transferred to JS Whites shipyard at Cowes IoW, working on Naval destroyers.
He joined Vickers in 1921 and, when the Second World War broke out, Barnes Wallis was Assistant Chief Designer at Vickers Armstrong Aviation Section at Weybridge where, independently of any Air Ministry requirement, he spent some time investigating how the energy sources of the Axis powers (Germany and Italy) might be reduced or eliminated.
Specialist publications provided him with all the necessary background information on the German dams and he formed the opinion that knocking out the water reserves of the Ruhr would curtail steel production severely.
Barnes Wallis was already developing his theories regarding large bombs and these were principally along the lines that a large and heavy bomb dropped from a great height would develop a sufficient velocity to penetrate deep into the ground before exploding, whereupon the shockwave formed and the collapsing camouflet effect formed by the underground explosion would demolish any target either directly over the bomb strike but, more importantly, for some considerable radius around it.
This was important as it was the use of the shockwave from the explosion travelling through the solid media (earth) which caused the main damage.
Barnes Wallis was well familiar with current aircraft design, having designed the Vickers Wellesley and the Vickers Wellington bombers, both at that time in use by the RAF. He was aware that no aircraft existed that could lift a bomb of the weight needed to a sufficient height for his plan to be put into effect. However, he quietly proceeded with his experiments and turned his mind towards reducing the amount of explosive that would be needed to demolish the dams.
He arranged for scale models of a number of dams to be built, including this replica of the Möhne Dam which still survives in the grounds of the Building Research Establishment at Garston.
The model was built in 1941, 2 years before the raid. Experiments proved that, if a relatively small explosive charge could be placed low down on the wet side of a concrete dam face, the shock wave caused by its explosion travelling through the water would be very much greater than the same explosive on the dry side of the dam and this enabled him to start considering ways and means by which an explosive charge could be placed as required.At the same time as these tests were taking place, Barnes Wallis prepared a paper entitled “A Note on the Methods of Attacking the Axis Powers” which he finalised in March 1941.
100 copies were circulated in military and political circles, the outcome being the formation of a committee, entitled the Aerial Attacks on Dams Committee, to take his suggestions further.
He obtained permission to blow up the Nant y Gro dam in Wales, which had been used to provide power for workers while they were building a bigger dam. On July 24th 1942, 280lbs of explosives were detonated against the wall of the dam at a depth of 10 feet. The blast blew a hole 60 feet wide and 25 feet deep in the dam wall.
The concept of a bouncing bomb was not invented by Wallis himself. Naval gunners in the 16th and 17th centuries discovered they could increase the range of their cannons by ‘bouncing’ cannon balls off the water like a stone in a pond. There were also reports from pilots early in the war who said that, even if they dropped their bombs short of enemy shipping under attack, they would sometimes skip on over the water and still hit the target under the right conditions. Knowing that he had to get the bombs to detonate right next to the dam wall, Wallis began to experiment with the concept of a bouncing bomb as means of doing so.
Wallis began his experiments with bouncing bombs at his home in Surrey. He used his daughter Elizabeth’s marbles to bounce off the surface of a metal tub and land on table further on.
He soon extended his experiments to the National Physical Laboratory ship testing facility at Teddington. Using the 670 foot long water tank, Wallis bounced many different spheres of various design and of various materials including smooth, grooved and even dimpled balls (similar to golf balls). In his experimentation he discovered that the ball must hit the water at a certain angle otherwise it would dive straight into the water without bouncing. The critical angle for the ball to bounce was about 7 degrees. This angle of impact had great implications as to the height from which the bomb would have to be dropped. Wallis also discovered that applying backspin to the sphere gave better results. If the sphere was spun backwards, it bounced better because it was more inclined to rise off the surface of the water. The backspin also increased the distance the sphere would travel due to the improved bouncing effect.
Also, after a certain number of bounces, the sphere would decelerate enough so that it would sink at the wall of the dam and not overshoot. After encouraging results from the test tank in Teddington, Wallis took his ideas, along with the test results, calculations and designs to the Air Ministry, the Ministry of Aircraft Production, the Admiralty and Vickers who he worked for.
He was told to construct and test six half size prototype weapons– they had the code name Upkeep. On December 4th 1942, using a Wellington bomber piloted by Vickers’ chief test pilot Mutt Summers, Wallis dropped his first test bomb just off Chesil beach in Dorset. After hitting the water, the bomb was torn apart into tiny pieces. All following tests were just as disappointing. The problem was that the casing which gave the weapon its spherical shape continued to break apart despite attempts to strengthen it. Although the casing broke, the bomb did bounce just as Wallis had suggested. He believed that, given time, he could solve the problems with the casing and deliver a fully working prototype of Upkeep.
Wallis wrote a paper called ‘Attacks on Dams’ which contained his progress on Upkeep and suggested suitable targets. He submitted the report to senior figures in both the military and Government. The response was far from what Wallis was expecting! The Ministry of Aircraft Production felt it could not cope with the manufacture of Upkeep along with the production of aircraft which at the time was its number one priority. Furthermore, head of Bomber Command, Air Chief Marshal Sir Arthur Harris, described Wallis’ idea as “Tripe of the wildest description”. He commented that the revolving mine would tear itself from the bomb bay and destroy the aircraft carrying it. He also said “The war will be over before it works – and it never will”. Harris did not want to lose any of his precious Lancaster bombers on a “wild goose chase” that stood little chance of success. He knew from previous attacks just how vulnerable his bombers were.
Luckily for Wallis, Chief of the Air Staff, Air Chief Marshal Sir Charles Portal, who was a central figure in the Air Ministry’s earlier plans to attack the dams, had also seen Wallis’ results from Chesil beach on film and was very impressed. Portal told Harris to make three Lancasters available for Upkeep testing. He told Harris, “If you want to win the war; bust the dams”.
Release point calculations
Obviously the “bouncing” bomb would skip across the water in a particular way, but there were still a lot of variables. Wallis needed to ensure the bomb would hit the water and bounce rather than sink, yet still ricochet high enough to clear the German anti-torpedo netting.
He also had to make sure the bounce of the arc wouldn’t fall short of the dam, or alternatively clear it entirely and promptly blow up the low-flying plane that had dropped it! After quite a bit of maths, Barnes Wallis calculated that the bomb needed to be dropped exactly 425 yards away from the dam, exactly 60 feet from sea level, while the plane was travelling at 222 miles per hour. (Initially, he had thought that the bomb could be dropped from 150 feet, but later had to revise this to 60 feet). As tests with spherical bombs had proved unsuccessful, a cylindrical design was selected and developed for the task. It weighed 4.2 tonnes and carried 3 tonnes of Torpex explosive. An electric motor spun the bomb up to 500 rpm before it was released.
This would be a hell of a feat even with modern technology. The Lancaster had a wingspan of 31 metres, which was actually greater than the distance from the underside of the plane to the water at the required altitude. This meant there was hardly any room to turn, even with the Lancaster’s impressive manoeuvrability. Ensuring this altitude was not a simple task in a Second World War-era plane. The problem was that the standard altimeter was useless at levels below 150 feet. On March 28th 1943 Gibson had flown over the Derwent reservoir to see how difficult it was to fly over water at 150 feet with hills all around. During the daylight he had no real problems but when dusk came he could not distinguish the horizon from the water surface and nearly flew into the lake.
The solution to flying accurately at low level was found by the Royal Aircraft Establishment. A year earlier they had been experimenting with spotlights fitted under Hudson bombers in order to gauge their height while attacking U-boats at night. It had not worked very well due to choppy waves in the sea but over a smooth lake it might. After experimenting with it for a while, two lamps were fitted, one in the nose and one behind the bomb bay. They were angled so that the two beams would meet when the aircraft was at exactly 150 (or, as it was finally, 60) feet. It would be the job of the navigator to look down through the starboard (right) cockpit window and talk the pilot down until the lamps met at the required altitude. This seems like a pretty genius idea until you remember that you have just put two enormous spotlights onto your aircraft while flying in a raid on enemy territory, which you’re doing at night on the premise that maybe they won’t see you coming. The craziness of this is magnified when you remember you are flying so close to the water that if you turned too quickly to avoid gunfire that you are helpfully providing a well-lit target for, you’ve just given the Möhne river one of your plane’s wings as a midnight snack.
Having dealt with the issue of altitude, the team now needed a way to quickly calculate distance. This had a surprisingly low-tech solution: using the dam’s twin towers as markers, a sight was constructed using two nails on a triangular frame at an angle that, when held to the eye, would obscure the dam’s towers when the plane reached the correct distance from the dam. While this was fine in theory, the aircraft vibrations made it difficult to use in practice. Some of the bomb aimers relied instead on Chinagraph marks drawn on the bomb aimer’s windscreen. Since the bomb had to be dropped 425 yards away from the dam, with the plane travelling at 222 miles per hour, that gave the pilot approximately twelve seconds to get an airplane that was longer than two and a half school buses clear of the dam they had just launched a 7,500lb bomb at.
Formation of 617 Squadron
Air Chief Marshal Portal gave the go-ahead to form the new elite squadron on 26th February 1943; 30 Lancasters were allocated to the new squadron, and a target date of May 1943 was set for Operation Chastise. A new squadron was formed at Scampton on 21st March 1943, initially known as “X” Squadron and latterly as 617 Squadron, and the 24 year old Wing Commander Guy Gibson was personally selected to lead it by none other than Air Chief Marshal Sir Arthur “Bomber” Harris, the Commander-in-Chief of Bomber Command. Gibson had flown 71 bomber sorties and an entire tour of 99 sorties on night fighters and was already the holder of four gallantry awards – the Distinguished Service Order and bar and the Distinguished Flying Cross and bar.
Gibson had 3 weeks to choose the crews for 617 and 8 weeks to train them. Unusually, Gibson had the authority to pick his own crews. They would have to be experienced veterans who had completed or nearly completed two tours. However, although many believe that 617 squadron was formed from the very best, highly decorated pilots and aircrew in the allied force, this was far from the truth. The majority of the squadron had no decorations at all and instead of having flown two tours, some were only one third of the way through their first tour. For some of the flight engineers, the dams raid was their first operational sortie. Gibson personally knew very few of the men including his own crew. Only Flight Lieutenant Bob Hutchinson, a radio operator had flown regularly with Gibson at 106 squadron. They had finished their tour together.
Although Gibson was not told the target officially, he was given a very good idea of what he was up against at a meeting with Wallis on March 24th 1943. This was the first time the two men had met. Wallis could not tell Gibson specific details of the mission as he was not on the list of people with clearance for a full briefing; he did however tell him as much as he could. After the meeting, Gibson left with the knowledge that his aircraft must attack the targets at a speed of 240mph at a height of 150 feet (according to calculations at that time); any variation on this and the plans simply would not work.
The flying was very intensive; night after night they practised, at first in borrowed Lancasters and later in the modified types as they came through from Avro. In order to make conditions as realistic as possible, they were told to fly over three main locations in England: the Eyebrook reservoir at Uppingham in Leicestershire, the Abberton reservoir near Colchester and the Derwent reservoir near Sheffield. It is important to remember that neither Gibson nor the crews were aware of their targets at this time, the information was absolute top secret and very few people knew. The crews were however beginning to guess what their target may be. At first the rumours were that the target was the German battleship Tirpitz.
While it may seem unlikely for experienced air crews, air sickness was the first problem many of them had when they started training. Flying at low level caused intense turbulent shaking of the aircraft – nothing like having the individual pieces of your plane vibrate so hard its bolts shear! Many of the crews who were used to operating at the rather smoother altitude of 10,000 feet suffered it. The airsickness was so bad that some of the men were prescribed sedatives, as though the mission weren’t already complicated enough without the addition of drugs to the mixture.
Each member of the crew had a vital role when it came to dropping the bomb. These were:
 Pilot – control of the aircraft
 Flight Engineer – speed of the aircraft
 Bomb aimer – aiming and release of bomb
 Navigator – passing height information to Pilot
 Wireless Operator – Controlling spin speed of bomb
 Air Gunners – defence suppression
The Lancasters were specially modified to take the bomb, and were known as Lancaster B Mark III Special (Type 464 Provisioning). Their configuration is shown below:
On May 11th 1943, just 5 days before the night of the attack, the squadron began training with actual Upkeep bombs at Reculver (although they were not actually filled with explosives). They were amazed to see the drums bouncing over the water right up to the beach. Still they did not know their targets! After seeing the weapon in operation, it reignited talk that the target was the Tirpitz or even U-boats.
The first drop of a fully armed Upkeep bomb was made by Sqn Ldr Maurice (Shorty) Longbottom on May 13th from 75ft, five miles off Broadstairs – the location had been changed from Reculver for security reasons. Spinning at 500rpm, it bounced seven times over ‘almost 800 yards’ without deviation. For this trial the theodolite camera was positioned ashore on the North Foreland almost broadside to the aircraft’s track, and Handasyde [another test pilot] flew the other Lancaster at 1,000ft and 1,000 yards away from Longbottom, with two cameramen aboard to operate the normal-speed camera. Handasyde had Gibson as observer, and Wynter-Morgan flew in Longbottom’s rear turret to watch the behaviour of the mine after release as it slowed to 55mph behind the aircraft. The film of this test showed that the water-spout when the mine exploded rose to about 500ft above Handasyde’s aircraft, and the estimated depth of detonation was about 33ft. For all concerned the day was eminently successful.
While on training with real Upkeeps at Reculver, both Shannon and Maudslay damaged their Lancasters by dropping their bombs too low and being caught in a huge column of water thrown up after it hit the water. By the time the attack came five days later, Maudslay’s aircraft could not be repaired and the attacking force was down to 19 aircraft from the 20 originally intended by Gibson. Gibson had picked 21 crews for the squadron, the 20 to fly and one reserve. Coincidently, both Divall and Wilson had sickness and their crews would not fly. This therefore left 19 aircraft and 19 crews. The attacking force had been determined out of Gibson’s hands
On May 15th the Squadron received Permission to Go – immediate attack of targets X, Y and Z (the Möhne, Eder and Sorpe dams) was approved for execution at the first suitable opportunity.
On the afternoon of May 16th Gibson’s black Labrador, Nigger, the squadron mascot, ran out into the road outside RAF Scampton and was hit by an oncoming car (which swerved into a ditch in an effort to avoid him) and was killed. At Gibson’s request, Ft Sgt Powell buried Nigger at midnight, while Gibson was leading the attack on the dams. His grave is still tended at RAF Scampton to this day.
The Order of Battle
The plan was for the aircraft to fly in 3 waves:
 Wave 1 – 9 aircraft to the Möhne and Eder dams
 Wave 2 – 5 aircraft to the Sorpe, Ennepe Lister and Diemel dams
 Wave 3 – 5 aircraft as backup for Waves 1 and 2
The first wave of nine aircraft (AJ-G, AJ-M, AJ-P, AJ-A, AJ-J, AJ-Z, AJ-L, AJ-B and AJ-N) would take off in three sections ten minutes apart. They would fly a southerly route, crossing the enemy cost at the Scheldt estuary in Holland. Their first target would be the Möhne dam. Wallis believed that only one Upkeep would be required to cause a breach in the dam. The planners allowed Gibson to use three, firstly in case one was not enough and secondly to expand the gap. Once the Möhne had been breached, the aircraft that had attacked and no longer had an Upkeep would turn back home, while the remaining aircraft with Upkeeps would go on to Target B – the Eder. After breaching the Eder, the process would be repeated and aircraft with remaining Upkeeps would proceed to Target C – the Sorpe.
The Sorpe would be the primary target of the second wave consisting of five aircraft (AJ-T, AJ-E, AJ-W, AJ-K and AJ-H). The second wave would actually leave Scampton first in order to fly a more northerly route to the Dutch island of Vlieland then down the Zuider Zee and join the flight path of the first wave just over the German border. The two routes were chosen to suggest to enemy radar that these were minor attacks. After attacking the Sorpe, the second wave would use any remaining bombs to attack the secondary targets – the Ennepe, Lister and Diemel. The third wave of five aircraft (AJ-C, AJ-S, AJ-F, AJ-O and AJ-Y) would leave Scampton more than two hours after the first two waves. They would follow the route of the first wave and act as mobile reserve to attack any of the primary targets that had not been breached or move onto the secondary targets. If all targets had been breached before they reached the Dutch coast, the reserve unit would be recalled. All crews were warned not to stray from the planned routes because they were designed to avoid flak batteries, night fighter bases and hot-spots all the way from the Dutch coast to the dams and back. They would maintain low level during the whole flight there and back. They were also warned that under no circumstances should anyone return with an Upkeep intact. It was far too dangerous to attempt to land with an armed weapon. They were advised to release the bomb, preferably over German land. After the briefing, the crews sat down to the traditional eggs and bacon before leaving to make their final preparations for the attack. Some wrote letters to their loved ones in case they did not make it back. Some made final meticulous inspections of their aircraft and weapon and one or two tried to make a last minute phone call, only to find that there was a security cover on all communications of any kind outside of the base.
The map above shows the approximate routes taken by the Dambusters from RAF Scampton to the dams in the Ruhr valley. The black line shows the route flown by the first and third waves. The purple line shows the route taken by the second wave. The red line shows the attack route on the primary targets (Mohne, Eder and Sorpe) taken by all waves.
Note: This map shows locations as in 2003 NOT 1943. It has been used to show the locations of the dams and the route flown to attack the dams.
At 21:28 hours the first aircraft of the second wave (AJ-E) started its take off run. Operation Chastise had begun.
The First Wave
At 21:39 Gibson’s Lancaster (AJ-G) took off. As the first wave passed through the Balkan area they encountered heavy flak and intense searchlight activity. This caused Gibson to break radio silence and issue a flak warning which Five Group rebroadcast to all the aircraft shortly afterwards with a detailed position report. There was also heavy flak to the north of Hamme on the approach to the railway marshalling yards.
The second flight of three aircraft of the first wave also encountered flak near Dülmen. The last flight of the first wave encountered stronger headwinds and consequently they were slightly late as they crossed the Dutch boarder into Germany. AJ-B piloted by Flight Lieutenant W. Astell were flying as low as they could to avoid the flak and search lights, but hit high tension wires and pylons 4km from Marbech. The aircraft reared up in the air, burst into flames, but then crashed to the ground. Two minutes later the mine exploded and all seven crew were killed.
Gibson arrived over the Möhne reservoir at 00:15 hours. The aircraft assembled in an anti-clockwise holding pattern 10 km south of Völlinghaussen whilst Gibson called AJ-B on the radio. Astell and his crew were already dead, but he did not know this. Gibson took a few moments to assess the target and its defences. It appeared to be as he had been briefed with three light flak batteries on the dam wall and three more in the valley. Gibson confirmed the attack would be carried out as planned by radio. Using the VHF radio Gibson assigned five of the remaining eight Lancasters to the attack. Gibson prepared for his run in, the weapon already having been spun up to speed by his W/Op. He first made a dummy run towards the dam to get the lie of the land. He flew through the flak fire before reporting on the VHF that “he liked the look of it”.
The attack run had been planned to allow the aircraft time to organise their direction, height and speed before crossing a spit of land that jutted out into the lake and becoming visible to the opposing flak guns. His Lancaster turned out of the holding pattern and directly towards the dam face over the landmark spit of land that guided the run in. They had to fly over the spit at 900ft before diving down to 60ft to release the bomb – the timing was incredibly tight. His bomb was dropped at 00.28hrs and was watched by the rear gunner to bounce three times before exploding against the dam face and throwing a vast column of water into the air. The bomb had struck approximately 150ft off the centre of the face of the dam and the dam had not collapsed.
Hopgood in AJ-M attacked next. The spotlights came on and he commenced his run into the now awaiting flak from the shore and the towers. The Lancaster was hit and started to burn on the port outer engine. Gibson noted damage to the port inner as well. Additionally, the starboard wing had received hits as well and it is little wonder that with these distractions the upkeep was dropped just a few seconds late, it hit, bounced and flew right over the top of the dam wall before exploding with a great violence down by the power generating house in front of the dam wall.
A red very light was fired by Hopgood’s W/Op and by now the Lancaster was brightly aflame from a petrol fire. The aircraft climbed to about 500ft and then the strain became too much and the starboard wing collapsed, sending the plane into a dive to crash and explode near the village of Ostonnen, 6km North West of the dam.
Gibson noted that he thought some of the crew may have survived and in fact three survived the crash and two survived to become POW’s. Burcher, the rear gunner jumped with his parachute open and in his arms and survived and F/Sgt Fraser, the bomb aimer, also made it out using the same method due to the low height of the aircraft. Minchin, the W/Op, was pushed out by Burcher but the altitude was too low and his parachute did not open in time to save him.
Martin in AJ-P commenced his run with Gibson flying alongside in an attempt to draw away the heavy volumes of light flak coming from the dam. His bomb threw up a similar large plume of water, but again the dam held.
Squadron Leader Dingy Young took the fourth attack in AJ-A. Martin flew parallel with him and instructed his gunners to take on the flak towers to try and reduce the amount of light flak. The guns had been loaded with all daytime tracer ammunition which made the fire appear much heavier than it actually was.
Gibson at the same time turned all of his lights on and flew over the dam from the south in a further attempt to draw the flak away. Again a tremendous plume of water but no break in the dam.
AJ-J piloted by Flight Lieutenant Maltby started his run for the fifth attack. Gibson and Martin flew alongside to take on the flak and Maltby’s bomb was perfectly placed. This time a plume of water shot to over 1,000ft into the air before collapsing back into the lake. The dam appeared intact and Gibson ordered Shannon to commence the sixth attack.
Whilst this was happening the main wall of the dam collapsed, revealing an enormous breach through which poured millions of gallons of water. All the anti-aircraft fire, save that from one gun ceased and the code word for a successful breach of this dam (Nigger) was transmitted to bomber command. The aircraft circled for a few minutes watching in awe as the torrent of water travelled down the valley, in some cases with the headlights of cars visibly being overwhelmed by the water and slowly turning green, then brown, before disappearing.
The operation, however, had to continue.
Maltby and Martin then set course for home whilst the three aircraft still with their Upkeeps (AJ-L, AJ-Z and AJ-N) flew to the south east accompanied by Gibson towards the Eder reservoir.
This was about 12 minutes flying time away. This journey was made without opposition, although in the moonlight identification of the dam itself proved initially quite difficult.
The approach to this target was even more difficult, dropping down past Waldeck Castle into a valley, flying towards the Hammerberg spit of land in the lake and then turning 90° left for a short run onto the dam face. The Lancasters started by circling into an anti-clockwise direction over Waldeck Castle and Shannon (AJ-Z) was given the task of the first attack.
AJ-L made three unsuccessful attempts to get the right position. Shannon was having problems achieving the required height and approach angle, so Gibson put him into a holding pattern and called Maudslay in AJ-L. He also had tremendous problems getting into position and Gibson ordered him to hold off. He put Shannon back onto the task and he made two further attempts before on the third he was able to drop the Upkeep. It bounced twice and exploded south of the dam without producing any visible result whatsoever.
Maudslay then came in again and he released his Upkeep during his second approach. He dropped his weapon slightly too late and it hit the crest of the dam and exploded with a brilliant flash lighting up the countryside for miles around. The explosion occurred right behind Maudslay’s Lancaster, which had just crossed the crest of the dam, and Gibson tried to raise him on the VHF. Other crew members reported hearing a weak unnatural, almost dismembered voice in reply and at the time it was believed that Maudslay had crashed, his aircraft having been damaged by the blast. In practice, however he had struggled away with a damaged aircraft and started on the return journey, but he was shot down by light flak at 02:36 at Emmerich-Klein-Netterdn. Maudslay and all of his crew died.
AJ-N, piloted by Les Knight, was then ordered to make its approach with Gibson flying alongside to suppress the flak. The bomb bounced three times and struck the dam to the south of the centre and exploded. The blast visibly shook the whole dam and then the central wall collapsed, allowing thousands of cubic yards of water to roar through the breach.
The Second Wave
Four of the aircraft took off normally. However, Flight Lieutenant Joe McCarthy in AJ-Q was not able to take off. His pre-flight checks revealed a coolant leak in the number 4 engine and consequently the whole crew changed to one of the reserve aircraft AJ-T and suffered a 20 minute delay in doing so.
Byers (AJ-K) was slightly off course and flew over a heavily defended island. He was shot down by flak off the Dutch coast at 23:00). There were no survivors.
Barlow (AJ-E) crashed near Haldern, Germany at approx 23:58. Reports said that he hit power cables. The rear gun bay broke away and the gunner survived, albeit with a broken back.
Munro (AJ-W) was hit over the Dutch coast at 23:00 and aborted the mission as the intercom had been knocked out and there was also a hydraulic problem.
Rice (AJ-H) lost his Upkeep at 23:00 over the Dutch coast after clipping the sea while trying to avoid the flak. The rear gunner felt the effect of the near crash most keenly – after the bomb had been ripped out, a sheet of water shot down the fuselage towards him, picking up the contents of the Elsan before nearly drowning him! Rice aborted the mission and returned home.
McCarthy took off approximately 34 minutes later than the rest of the second wave. He attacked the Sorpe dam at 00:46. It was immediately apparent that the approach to the dam was extremely challenging, and so it proved.
McCarthy flew the approach nine times but found it difficult to clear the high hill and then bring the Lancaster down low enough, with the church steeple on the approach proving particularly troublesome, and either McCarthy himself or his bomb-aimer were not satisfied that all was right and called for the aircraft to go around again. The other members of the crew became restless as the bomber had now been circuiting the dam for half an hour and they were also puzzled that no other aircraft from the second wave had appeared. Eventually, on the tenth approach both McCarthy and his bomb-aimer were satisfied that the approach was perfect and dropped the bomb alongside the dam.
Two and a half hours later Brown, who had received a radio message directing his aircraft to attack the Sorpe while in the air, arrived at the dam and found that the ground mist was now even thicker. Brown found the approach no easier than McCarthy, and the thickening mist made flying the circuit correctly difficult even though the dam itself was clear, and after flying into a mist-bound nearby valley and nearly crashing he ordered that incendiaries be dropped round the circuit to help him.
In all Brown flew five separate approaches before dropping the mine on his sixth attempt. Although both mines exploded close to the dam and caused considerable damage, no breach occurred. The loss of so many from the second wave had seriously weakened the assault on the Sorpe and it survived the attack.
Third Wave
Ottley (AJ-C) was shot down over Hamm, Germany at approx 02:35. There was one survivor, Tees, who became a prisoner of war.
Burpee (AJ-S) was shot down over Gilze-Rijen airfield in Holland at approx 02:00 . There were no survivors.
Brown (AJ-F) attacked the Sorpe dam at 03:14 as described above.
Townsend (AJ-O) attacked the Ennepe dam at 03:41 but failed to breach it. AJ-O was the only aircraft to attack any of the secondary targets and was the last aircraft to return.
Anderson (AJ-Y) did not attack a target and returned with Upkeep intact.
The 617 Squadron dams raid tally
19 aircraft took off to attack the dams:
 3 turned back;
 5 were lost before the attacks;
 11 aircraft attacked the dams;
 1 aircraft was lost during the attack;
 2 aircraft were lost after the attack;
 8 aircraft returned.
Decorations were awarded to 34 members of the air crew: Victoria Cross – 1; Distinguished Service Order – 5; Distinguished Flying Cross – 10; Bar to Distinguished Flying Cross – 4; Conspicuous Gallantry Medal – 2; Distinguished Flying Medal 11; Bar to Distinguished Flying Medal – 1.
53 air crew were killed in action.
Barnes Wallis took the loss of life very badly. His daughter said that he never got over it and when, after the war, Wallis was given £10,000 as an ‘Inventors Award’, he would not accept it. He said: ‘I will not touch the money, it is blood money.’ He quoted some words of David from the Bible: ‘Is not this the blood of the men who went in jeopardy of their lives’. However, he used the award to fund a bursary at his old school, Christ’s Hospital, for the children of RAF personnel killed in service. Barnes Wallis continued to work at his desk into his 80s and died on 30th October 1979, at the age of 92.
In discussion, Dudley was asked if he thought the raid was worth it, given the high number of casualties. He said that it was, for a number of reasons: it cost the Germans about 6 months’ production at a critical time; it diverted resources to rebuild the dams, who might otherwise have been working to strengthen defences in Normandy; there was a significant effect on British (and German) morale; and it also affected President Roosevelt. Finally, to paraphrase a remark by one of the 617 aircrew, if you weren’t there, you aren’t entitled to comment!
Our thanks to Dudley Hooley for another inspiring talk. This report makes extensive use of pictures and notes form his presentation, but it doesn’t do full