Was the legendary and courageous 1943 RAF Dambusters Raid a 'strategic success or a conjuring trick'? PAUL STODDART from the RAeS Air Power Group provides a report on an academic debate on the effectiveness of Operation CHASTISE. [caption id="attachment_8142" align="alignnone" width="372"] Lancasters on the way to the target - a still from the Dam Busters film. (RAeS/NAL)[/caption] Seventy years have elapsed since 617 Squadron led by Wing Commander Guy Gibson breached the Mohne and Eder dams in western Germany on the night of 16-17May 1943.  Despite the passage of time, the release of previously classified information and the intensive study by historians, opinion remains divided as to the effectiveness of the operation.  To commemorate what remains one of the most, if not the most famous single air power action, on 4 April the Cranwell branch of the RAeS devoted its annual Trenchard Lecture to a debate on Operation Chastise. The three speakers were the distinguished historians and authors Professor Eric Grove, Dr Peter Caddick-Adams and James Holland (biographical details below). The debate was hosted by the Royal Air Force College Cranwell and took place in the splendid setting of College Hall Officers’ Mess with an audience of around 80. Cranwell is a few minutes flying time south of RAF Scampton from which 617 Squadron flew on the Dams Raid.

Divided Opinions

The official history[i]: “…the most precise bombing attack ever delivered and a feat of arms which has never been excelled”.   “...the effects of this brilliant achievement upon the German war machine were not, in themselves, of fundamental importance nor even seriously damaging”. “The truth about the Dams Raid is that it was a conjuring trick, virtually devoid of military significance…The story of the raid is one of sloppy planning, narrow-minded enthusiasm and misdirected courage”[ii]. The most widely read account of the RAF’s contribution to the strategic air offensive against Nazi Germany is probably Max Hastings’ ‘Bomber Command’[iii].  Of the 425 pages, barely a page is actually assigned to the Dams Raid and Hastings sums up the operation as follows: “The Ministry of Economic Warfare in London correctly judged that the Mohne and the Sorpe dams were central to the Ruhr water supplies.  But after destroying the Mohne, 617 Squadron used their remaining mines to wreck theEder dam, which was quite irrelevant.  Bomber Command had merely judged it more easily breachable...than the Sorpe”. “Operation CHASTISE achieved considerably more than it has been given credit for, particularly by latter-day historians. The Dambusters Raid was a legendary feat and a remarkable strategic success; its undoubted accomplishments do not deserve to be belittled unjustly”[iv]. The ever quotable Sir Arthur ‘Bomber’ Harris offered this assessment of the Upkeep mine: “It was...designed...outside the...Air Ministry; it [was] almost a rule that such weapons were successful, while those produced by the official organisation were too often failures”[v].
  [caption id="attachment_8144" align="alignnone" width="333"] Map showing the route of the raid.[/caption]

The Debate – Opening Statements – Opening Salvoes

Dr Peter Caddick-Adams The debate opened with each speaker offering an initial statement on the operation’s aims and effectiveness. Dr Caddick-Adams began by asking the rhetorical question as to how success should be defined so that the operation could be objectively assessed.  He emphasised that much of the general understanding of the raid is based on the media’s 1943 presentation of the results, i.e. a less than impartial view.  In early 1943, though the Allies had defeated the Axis in North Africa, the Eastern Front was still undecided. American forces were building up in the UK representing a growing challenge Britain’s leadership role in the West. It was therefore understandable that the headlines were very positive and the accounts offered an exaggerated assessment of the results achieved. Dr Caddick-Adams emphasised that the raid should not be considered in isolation but in the context of Bomber Command’s Battle of the Ruhr.  That campaign ran from March to July 1943and involved 43 raids and around 18,000 sorties in which 872 aircraft were lost.  That was a rate of 4.8% i.e. above the usually accepted limit of 4%; when damaged aircraft were included the casualty rate was 11%. The aim of the five month campaign was to neutralise the German war economy yet arms manufacturing was already widely dispersed. The London based Ministry of Economic Warfare (MEW) questioned the focus on the Ruhr pointing out that, for example, the region contained only one aircraft factory. In short, the Ruhr while important was not the sole target worthy of attention.   James Holland James Holland opened by referring to the book on the raid that preceded his own.  John Sweetman’s ‘The Dambusters Raid’ was originally (sub) titled ‘Epic or Myth’, a comment on the stark contrast between the various schools of thought.  He noted that using Google image search for Guy Gibson produced as many photos of the actor Richard Todd who portrayed him in the film.  Similarly, the film is often the entirety of people’s knowledge of the operation.  The film portrays a hard pressed wartime Britain that still has real clout and the nation can be proud of the achievement. It also presents Barnes Wallis (through Michael Redgrave’s portrayal) as a detached academic rather than the very effective networker Wallis actually was. Another misrepresentation is that of Wallis single-handedly promoting his dams attack scheme in the face of reactionary opposition from the Air Ministry.  He was a friend of Group Captain Winterbottom[vi] who worked in RAF Intelligence and who was extremely well connected with influential officials. Additionally, the Air Ministry had, in 1937, identified the importance of the Ruhr dams but had also noted the difficulty of breaching them. To some extent Wallis was pushing on an unlocked door and the scepticism he faced from certain quarters was not unjustified given the challenge of using Upkeep successfully.  For example, the commander-in chief of Bomber Command, Air Chief Marshal Harris had taken over a year to build up the force for his area bombing campaign.  He viewed low level attacks (as required for Upkeep) as being unacceptably dangerous and with insufficient prospects of achieving the significant results claimed by the ‘panacea merchants’ promoting them. Harris objected to the conversion of up to 30 Lancasters for Upkeep and advocated to the Chief of the Air Staff (CAS), Sir Charles Portal, against this.  To his credit, when Portal authorised Operation Chastise, Harris did all he could to ensure its success.   Professor Eric Grove Professor Grove emphasised that the aim was to inflict decisive damage on the ‘white coal’ of the Ruhr; the dams provided hydro-electric power, water for steel making (each ton of steel required eight tons of water) and drinking water for a very densely populated region. The British had studied the region and the MEW had correctly identified the central importance of the Mohne and the Sorpe dams to the Ruhr. The Upkeep mine was specifically designed to attack masonry built gravity dams such as the Mohne while the Sorpe was of earth buttress design and so was far less vulnerable.  Nevertheless, Wallis believed that several Upkeeps dropped on the crest of the Sorpe; the aim being to crack the concrete core causing leakage and eventual breaching or forcing the reservoir to be drained to enable repair. Relatively little effort was expanded in determining how best to attack the Sorpe and in the course of planning, the operation developed to exploit the weapon rather than to achieve the overall aim, i.e. to disrupt theRuhr’s industry. Thus the raid focus was the Mohne and theEderdams with the Sorpe as an afterthought. (It should be noted that while the Eder was a gravity dam and so vulnerable to Upkeep, it was not in the Ruhr valley. It held back the then largest reservoir in Europe).  Had the Mohne and Sorpe been breached, the resulting effects would have been much greater. Of the five aircraft allocated to the Sorpe, only one reached the target[vii]; it bombed accurately damaging the dam crest.  The main force of nine aircraft expended five mines on the Mohne and the remaining four on the Eder.  Of the reserve wave of five aircraft, three were directed to the Sorpe and two to less important dams in the Ruhr Valley. Of the Sorpe ‘three’, one never reached the target, one hit the dam causing further damage and the third could not locate the Sorpe in the thickening mists of the early morning. Of the other two aircraft, one was lost and one attacked the Bever Dam (instead of the intended target, the Ennepe Dam) but caused no damage. Professor Grove stressed that he was not denigrating the value of the operation though the loss of eight aircraft from nineteen (42% and 53of 56 crew killed) was very heavy. If applying the crude measure of people killed, the raid might be deemed effective. Sixty eight people were killed per aircraft committed and 162 per aircraft lost; the figure for a conventional raid on Dortmund was one tenth of the latter measure. In the still controversial February 1945 attack on Dresden, 37 people were killed per aircraft committed. Operation Chastise did not knock out the Ruhr but it was a significant addition to Bomber Command’s most productive campaign. Professor Grove agreed with the conclusion of a recent, notable history of Germany’s wartime economy[viii] specifically that the Ruhr campaign was a great success and “stopped Albert Speer’s expansion plan in its tracks”. During June and July 1943, the Ruhr’s output fell. Harris had been right; the Dams Raid did not achieve all that had been hoped (and claimed) for it but it was still effective.  It was also very good for British prestige in Washington (and Moscow) “eating the 8th Air Force’s sandwiches” by showing that the RAF could also achieve precision bombing as well as conducting area bombing. Professor Grove summed up his introduction by likening Operation Chastise to the Battle of Trafalgar. The significance of Trafalgar could be argued on the grounds that the war against Napoleonic France continued for a further ten years. Yet Trafalgar was “an important outward sign of inward grace” in that it demonstrated the Royal Navy’s capability and professionalism. Likewise, the Dams Raid did so for the RAF.  

The Wider Debate

James Holland pointed out that prior to the operation, there were differences in opinion as to what it was likely to achieve – even among the supporters. In fact, Wallis was one of the few (perhaps the only person) who believed that breaching the dams would result in cataclysmic effects that would substantially shorten the war.  He was convinced that cutting off the power to the Ruhr would cause production to practically cease. However, others had less ambitious expectations for Upkeep’s capability and hence the raid was planned around the weapon. That is, its suitability for gravity dams was an important factor notwithstanding the importance of the Sorpe Dam. The operation was actually more successful than some commentators have claimed even though it was achieved less than the 1955 film implied.  (The Hardest Victory: Eleven factories were destroyed and 114 damaged.  2822 hectares farmland were ruined with 6316 farm animals killed. Twenty five road bridges were destroyed, with ten damaged.  Various power stations, pumping stations, water and gas facilities were put out of action with serious disruption to water, electricity and gas supplies). To some extent, the criticism of the last 30 years or so has been a reaction to the original overstatements. The rebuilding of the Mohne and Eder was achieved remarkably rapidly (around five months – building the Mohne took five years) and the fact that considerable effort was devoted to this is proof of Chastise’s success.  Although there was no immediate water shortage in the Ruhr, it was necessary to rebuild the dams quickly in order to collect the winter rains and so provide water in 1944. The dams were also iconic structures for the German population; examples of Teutonic achievement. Breaching them was an affront that demanded a prompt response.  Rebuilding diverted considerable effort from other projects (48 hours after the raid, 7000 workers were heading for clear-up and rebuilding work in the Mohne valley, the Eder valley,Dortmund and Kassell. Another 20,000 were also assigned to various repair tasks with many diverted from the building of the Atlantic Wall). James Holland concluded by emphasising that all wartime commanders and planners seek major damage from relatively small effort; despite 617’s losses, the Dams Raid was one of the rare cases to actually achieve this. Peter Caddick-Adams offered three points. Firstly, he referred to one of the principles from Sun Tsu’s ‘The Art of War’ – to avoid costly attritional conflict but instead ‘fight smart’ and strike your opponent so as to cause major loss at comparatively low cost. In this respect, Operation Chastise was successful. Admittedly the headlines and newsreels of the day included some wishful thinking and certainly the Third Reich was not in danger of collapse owing to the damage caused. However, Britain was engaged in a titanic contest and the maintenance of national morale was extremely important so making some overstatement understandable in the circumstances. Secondly, the raid must be seen in the wider context of WW2 as a whole and 1943 in particular.  In early 1943, the Allied leaders met at the Casablanca Conference to decide their strategy for defeating the Axis powers. There was much debate as to how best to engage Nazi Germany with the Americans advocating a landing in France during 1943.  Churchill believed that to be excessively risky and he succeeded in postponing the invasion to the following year. However, this option depended on the expansion of the strategic bombing offensive and an increase in its effectiveness.  The UK-US relationship was that of an ad hoc coalition; the two nations had common interests but there was also competition between them.  The American view was that the RAF’s area bombing policy was less effective than the 8th Air Force’s daylight campaign.  Chastise was an example of British ingenuity (to both the US and the Soviet Union) and of the ability to achieve precision and significant effect in a night attack. Thirdly, it is worthwhile examining the Dams Raid from the perspective of effects-based operations (EBO) and Clausewitz’s theory of the centre of gravity (CoG), i.e. an indispensable capability.  The principles of EBO include seeking actions likely to achieve significant, beneficial results. While that may seem obvious, military history offers many examples where actions were taken because they were could be taken rather than because they were the best option. An adversary’s CoG is the essential component of their ability to fight. Wallis believed that power generation was the CoG of Germany’s war making capacity and that breaching the dams would neutralise it – a war winning result.  This was an unrealistic view given the resilience of the German economy but it is also a slur to describe the raid as a ‘conjuring trick’ – the operation caused significant damage. Following the general consensus between the speakers there was than a difference in views between James Holland and Professor Grove.  The former proposed that some ‘mission creep’ occurred with the RAF going beyond the initial aim of damaging the German war economy. Effects beyond the economic were considered worthwhile hence the focus on the Eder Dam after the Mohne was breached.  Destroying two iconic structures had very significant psychological effect.  The gravity design Eder Dam was not only vulnerable to Upkeep but it also held the largest reservoir in Germany[ix].  Professor Grove strongly disagreed.  He emphasised that the whole logic of the raid was to inflict industrial damage and to maximise that it was essential to breach both the Mohne and the Sorpe[x]. (See the section: The background to operation Chastise) As this was not achieved, the operation could be judged to have failed on the basis of its original aims. However, he expressed his respect for the achievement of the crews and noted that the raid was cost effective in terms of the results despite the heavy losses.  It achieved a great deal but suffered from being developed in great haste (James Holland concurred) and subsequently achieved both less than what was intended and what might actually have been possible. Dr Caddick-Adams noted the importance of raising the morale of both the British population but also that of Bomber Command which, at that time, was fighting the Battle of the Ruhr. Operation Chastise achieved these aims. It was timely as the Command had just completed a series of thirteen attacks on the U-Boat pens on the French Atlantic coast; many aircraft were lost and not one pen was destroyed. (Professor Grove interjected here pointing out that the RAF waited until these massive structures had been completed before attacking them). James Holland agreed with the value of maintaining the morale of the hard pressed bomber crews. The achievement of spectacular results was important and that was a factor in selecting targets on the basis of weapon suitability and hence likely effectiveness. In short, selecting the Eder made sense. The Ministry of Economic Warfare was correct in identifying the importance of the Sorpe but it was focused on the industrial level and not the wider issues such as morale and national influence. (Note: 27 Mar 43: A Chief of the Air Staff memo to Combined Chiefs of Staff stressed the value of  “The economic and moral” effects). The last point was taken up by Dr Caddick-Adams.  On 19 May 1943, Churchill addressed a joint session Congress in Washington. The dramatic results of the operation strengthened both his credibility and that of Britain as a whole.  Within the American political and military establishments, there were strong proponents of defeating Japan before Germany. Churchill’s advocacy of the ‘Germany first’ option gained considerable force from Chastise’s success; the raid illustrated British determination and capability. Professor Grove agreed on the value of the resulting political capital but noted that the operation was not planned for such a reason.   [caption id="attachment_8145" align="alignnone" width="200"] Mohne Dam after the attack. (Crown Copyright)[/caption]

Questions and Answers

Q: The questioner (Mr Jim Shortland, a committee member of the RAeS Cranwell branch) began by noting that the Sorpe Dam was not attacked again until 15 October 1944 when 9 Sqn used a series of the 12,000-lb Tallboy earthquake bomb against it. (This resulted in several huge craters and minor spillage). He then asked whether the 50-ton (loaded weight), six-engine Victory bomber[xi] (also proposed by Barnes Wallis) for the attack of gravity dams might have been effective. JH: Wallis proposed the Victory in 1940 when the resources required were definitely not available. (In fact, it went no further than a wind tunnel model. Three prototypes of the Wallis designed Windsor bomber (4 engines, 25-ton loaded weight) were built but it proved superfluous given the capability of the Lancaster). Wallis was an idealist and certain of his ideas were definitely ahead of their time. Some of the opposition to Upkeep was due to concerns that it would divert scarce resources from the Windsor’s development. His determination could reach levels of stubborn single mindedness and impatience with what were reasonable concerns about his plans.   Q: Wallis knew that Upkeep was unsuitable for an earth dam such as the Sorpe. Why were other methods of attacking it not considered? JH: Wallis believed that five or six Upkeep mines dropped precisely on the crest of the Sorpe (i.e. on the top edge of the concrete core) would damage it sufficiently to start serious leaks through the core.  The damage would progressively increase and eventually require the reservoir to be drained to enable repair.  This would amount to breaching the dam. EG: The attraction of the Eder Dam was that it was vulnerable to Upkeep and the prospect of two spectacular successes was very tempting. The planners, almost instinctively, selected the targets for the weapon rather than seeking the weapons for the targets.   Q: Why was the Lister Dam a target? (Note: The operation order listed several secondary targets: the Lister and Ennepe Dams in the Ruhr Valley and the Diemel Dam in the Eder region. One of the reserve aircraft was ordered to attack the Ennepe but is believed to have (unsuccessfully) attacked the nearby Bever Dam). JH: The best crews were assigned to the first and second waves. The reserve wave (five aircraft) was something of an afterthought. There was a lack of situational awareness at 5 Group HQ as to which aircraft were available and a lack of focus as to how best to use the remaining after the Mohne and Eder had been breached. EG: The aircraft ordered to attack the Ennepe should have been directed to the Sorpe which was a far more important target. (Note: Of the five aircraft originally specifically assigned to the Sorpe, only one reached it. Two had to turn back and two were lost en route). The Sorpe was attacked in an ad hoc, half hearted manner after the Mohne and this point is the main criticism of the handling of the operation itself (JH concurred).   Q: Hindsight is always 20:20. The task was to seriously damage the German war machine and there were great challenges in achieving the required weight of effort and accuracy. Should a different weapon have been used against the Sorpe? PCA: The more variables there are in a military operation, the greater the chance of failure. The leaders of the RAF in WW2 had all served in WW1 and knew of the difficulties of introducing new technology. Developing another weapon specifically for earth buttress dams such as the Sorpe would have been a major additional cost and one that was probably unaffordable at the time given the multiple demands on British industry. EG:  There was no question of a second type of weapon. The operation was based on Upkeep and target selection was driven by its effectiveness.   Q: Were there any further plans to use Upkeep? EG: The smaller version of Upkeep, Highball, was an anti-ship weapon intended for use against capital ships such as the German battleship Tirpitz. In the event, Highball was never used. (Note: The original plan was for concurrent use of Upkeep against the dams and Highball against Tirpitz. Highball had development problems which delayed it beyond the mid-May deadline of attacking the dams, i.e. when the reservoirs were full). Upkeep was not used again though it was considered for attack of some Italian dams and the Dortmund-Ems Canal in theRuhr. After Chastise, the Germans devoted considerable effort to repairing the dams and to protecting them and other dams as well.   Q: Why did Harris (AOC-in-C of Bomber Command) fixate on area bombing when it was not effective? EG: Area bombing was successful in some cases. It achieved significant effect on theRuhr’s industrial output especially the production of spare parts. Speer’s plans to increase Ruhr production considerably in 1943received a major set back from Bomber Command’sRuhr campaign. Harris’s mistake was to switch from the Ruhr to Berlin where less industrial damage was achieved while our losses increased. PCA: The area bombing scheme arose from Britain’s experience in the 1940 Blitz. The greatest effect on morale was where people lost their homes. One aim of the area campaign was to ‘de-house’ the population and so damage their morale. The measure applied was the number of buildings ‘de-roofed’, which was reasonably readily assessable from aerial photography. In the event, Bomber Command tried to something of everything and hence achieved less than a more focused approach. Principal target types identified for the strategic bombing offensive included U-Boat and aircraft production, fuel, synthetic rubber and ball bearings. There were many tempting targets and all of them were tried. The focus should have been on synthetic fuel and synthetic rubber production.  Instead, Bomber Command had an inconsistent approach throughout the war; it suffered from ‘mission shift’. JH: Both Bomber Command and the USAAF 8th Air Force attacked the morale of the German population.  But Nazi Germany was not a democracy and so was not open to public opinion changing state policy. Area bombing definitely reduced German output and especially efficiency as it forced the dispersion of much of the industry. EG: The German economy was relatively weak at the start of the war, robbing Peter to pay Paul – ships or tanks but not both. At times, Bomber Command inflicted great damage to German industry but on other occasions it was misdirected. There were two particular examples of this. Harris’s resistance to allocating long range aircraft to Coastal Command delayed closing the mid Atlantic ‘Air Gap’ and so prolonged the effectiveness of the U-Boat campaign against Allied shipping. Had that been resourced sooner, it would have paid dividends. The mining of the Baltic from the air was also very effective in hampering U-Boat operations.   Q: What would you say to Harris if you could meet him today? JH: I would love to have dinner with Harris. He was a force of nature. He is perceived now as being more influential than he actually was at the time in terms of planning and carrying out the bomber offensive which was of course directed ultimately by the politicians such as Churchill.  Most unfairly, he has ‘copped the blame’. The vandalism on his London statue, daubed with red paint, is unjust and hurtful. Bomber Command made a major contribution to defeating Germany and that should be remembered. EG:  Keep hammering the Ruhr and give Coastal Command some Lancasters. PCA: Harris has had a bad press. The moral component is crucial in war and Harris exhibited great strength of character. Churchill drove the British war effort but he was an amateur strategist who often bullied others into accepting his ideas. Field Marshall Alan Brooke (Viscount Alanbrooke) the Chief of the Imperial General Staff commented in his diary that Churchill had dozens of ideas every day and only one of them was any good (and Churchill didn’t know which one it was). Churchill could browbeat almost anyone but Harris was able to resist and to achieve continuation of his own policy. In short, he was a very considerable figure in WW2. [caption id="attachment_8146" align="alignnone" width="333"] The Dambusters Memorial today.[/caption]  

[i] Webster, Frankland.  ‘The Strategic Air Offensive Against Germany 1939-1945’.  Vol III: Victory, Part 5.  1961.  HMSO.
[ii] Knightly, Phillip.  ‘The First Casualty: The War Correspondent as Hero and Myth-maker from theCrimea to Kosovo’. London.  Prion Books.  1975.  Knightly attributes the quote to a Bruce Page article ‘How the Dambusters’ Courage was Wasted’.  Sunday Times Magazine, 28 May 1972.
[iii] Hastings, M. ‘Bomber Command’.
[iv] Gilligan, M, Wg Cdr.  RAF Air Power Review, Spring 2006.
[v] Harris, A.  ‘Bomber Offensive’.  1947.
[vi] Author of ‘The Ultra Secret’ the first book to recount the breaking of the German’s Enigma cipher.
[vii] Two suffered damage and had to return before attacking the Sorpe, one was shot down and one hit power lines and crashed, a distinct possibility for low level flight in darkness.
[viii] Tooze, Adam.  The Wages of Destruction: The Making and Breaking of the Nazi Economy. Allen   Lane.  2006.
[ix] Reservoir capacities: Mohne 135 million cubic metres (equal to 135 million tonnes); Sorpe 70 million;Eder 200 million.
[x] Albert Speer, the Reich Minister of Armaments stated that had both the Mohne and Sorpe been breached then "Ruhr production would have suffered the heaviest possible blow."
[xi] Wallis designed the Victory bomber to carry his 22,400 lb (10,200 kg) Grand Slam bomb.  The Victory was never built and Grand Slam was eventually carried by modified versions of the Lancaster. It was estimated that it could breach dams such as the Mohne by detonating in the ground under the reservoir within 150 ft (46 m) of the dam's face.

The Background to Operation CHASTISE

Oct 37: Western Air (WA) Plans (16 in total) drawn up by the Air Staff for use in war against Germany.  WA5: ‘to attack the German War Industry including the supply of oil with priority to that in the Ruhr, Rhineland and Saar’.  Bomber Command proposed focusing on 19 power plants and 26 coking plants in the Ruhr – identified as vital.  Claimed that 3,000 sorties over one fortnight (cost 176 ac) would bring war production to virtual halt.  The Air Targets Sub-Committee proposed attacks on Mohne and Sorpe dams. Sep 37: AI1(b) [Air Intelligence] of the Air Ministry did a study of dams, reservoirs and aqueducts.  Identified 3 types of dam as targets with examples of each including dimensions and reservoir capacity.  Director of Armament Development concluded that with existing weapons, successful attack of a gravity dam was ‘highly problematical’. 19 Mar 38: Dir of Staff Duties, Air Ministry reviewed BC Paper No 16 ‘Air Attacks on Reservoirs and Dams’ – supported re-examination of the option re ‘newly developed weapons’. Aug 41 Butt Report: in the Ruhr only one aircraft in 10 was getting within 5 miles of the target. 18 Mar 43: Ad Hoc committee (including Admiralty representatives) agreed that Sorpe should be ruled out.  The targets should be the Mohne and possibly the Eder.  Also agreed that an attack on Tirpitz or other German capital ship in the Norwegian fjords using Highball (a small version of Upkeep designed as an anti-ship weapon to be dropped from Mosquitoes). Feb 43  Combined Chiefs of Staff directive to Bomber Command: “Your prime objective will be the progressive destruction and dislocation of the German military, industrial and economic system, and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened”. End 42 Wallis finished 2nd major paper on attacking industrial targets ‘Air Attack on Dams’.  Reached AM R S Sorley ACAS Technical Requirements on 05 Feb 43. 26 Feb 43: Go-ahead given for Op CHASTISE; 80 days to the attack. 28 Feb 43: Air Staff recommended that Highball should not be employed independently; attack of Tirpitz by Mosquitoes in daylight was considered ‘problematical’ and liable to compromise the system. 18 Mar 43: committee noted ‘the 2 most important dams vulnerable to attack in Germany are the Mohne and the Eder’.  The committee ‘ruled out’ the Sorpe ‘as being unsuitable for attack for tactical and technical reasons’. 08 Mar 43: Conversion order with Avro for the Type 464 Provisioning Lancaster. 08 Mar 43: ad hoc committee established by chiefs of staff ‘to co-ordinate the plans and preparations for Operation Highball…’. 27 Mar 43: Portal, CAS, circulated to CoS Committee a paper entitled ‘The Economic and Moral Effects of the Mohne Dam and the Added Effects Which Will Result from Destruction at the Same Time of the Sorpe and Eder Dams’.  It stated that Mohne and Sorpe together supplied 75% of the Ruhr’s water.  With respect to the Eder ‘destruction of this dam would be speculative, [and] economic effects would be problematical…..From the economic standpoint, therefore, this dam cannot be considered as a first-class target’. 02 Apr 43: MEW – if the Sorpe were simultaneously attacked and destroyed with the Mohne it ‘would be worth much more than twice the destruction of one’.  Also emphasised that the Eder had no connection with the Ruhr. 05 Apr 43: Bomber Command memo to CAS proposing simultaneous attacks on the Mohne and Sorpe with an attack on the Eder only to follow if the circumstances were favourable. 10 May 43: AOC 5 Group – draft plan: Bulk of the sqn was to attack the Mohne and then the Eder; concurrently about 4 ac whose crews ‘did not reach the highest standards of accuracy’ were to attack the Sorpe. 13 May 43: Axis forces in North Africa surrender.  Op Order B.976: The priority target is stated to be the Mohne with the Sorpe ‘next in importance’.  However, the order states that the dams should be breached in the following order: Mohne, Eder, Sorpe.  Three ‘last resort’ targets, the Lister, Ennepe, and Diemel dams are listed; the Diemel was related to the Eder.  (Comment: The Lister and Ennepe were in the Ruhr.  Had the Mohne, Sorpe, Ennepe and Lister all been breached, there would have been potentially catastrophic effects on the Ruhr). The 1st wave (3 sections of 3 ac) were assigned to attack the Mohne, then the Eder and finally the Sorpe.  The 2nd wave (5 ac) were all assigned to attack the Sorpe.  The 3rd wave was to act as an airborne reserve (6 aircraft were planned but only 5 flew).  (See the Actions and Results section)  

The Reckoning: ‘The Hardest Victory’

In the Möhne and Ruhr valleys 11 factories were destroyed and 114 damaged.  A total of 2822 hectares farmland ruined and 6316 farm animals were killed. Twenty five road bridges destroyed and ten damaged.  Various power stations, pumping stations, water and gas facilities were put out of action.  Power, water and gas supplies were seriously disrupted throughout the region though industrial production was back at normal level by September, however. 27 Jun 43: Water production for the Ruhr’s industries had recovered to pre-raid levels.  

Actions and Results

Gibson led nine aircraft to attack the Mohne and then the Eder.  Five aircraft were assigned to the Sorpe with five assigned as a reserve.  At the Mohne, two of the five bombs released were accurate and the dam was breached.  At the Eder, the fourth bomb breached the dam.  One of the five aircraft assigned to the Sorpe reached it; its bomb was dropped accurately and caused some damage to the dam.  Of the reserve wave, three ac were directed to attack the Sorpe and the remainder to other dams.  Of the three directed to the Sorpe, one did not arrive, one dropped its weapon on the dam and the 3rd could not locate the target.  

The Sorpe Aircraft – (Bad) Luck was a Major Player

Second wave: 5 aircraft assigned to attack the Sorpe. W-Willie (Munro) hit over Vlieland losing compass, intercom and VHF radio.  Returned to base. K-King (Byers) shot down over Texel. H-Harry (Rice) hit the surface of the sea losing the mine.  Returned to base. E-Easy (Barlow) hit power lines and crashed.  T-Tommy (McCarthy) attacked Sorpe at 00:46 F-Freddie (Brown) attacked Sorpe at 03:14 Thus two out of the two Upkeeps actually directed at the Sorpe hit the target and caused some damage; this was the highest hit rate for any of the dams attacked.  However, it was well short of the five to six mines that Wallis believed were necessary to cause substantial damage to the crucially important Sorpe Dam.  

Speaker biographies

Professor Eric Grove studied history at the University of Aberdeen, gained an MA in War Studies at Kings College London and a PhD at the University of Hull. He is currently the Professor of Naval History and Director of the Centre for International Security and War Studies at the University of Salford. His books include Vanguard to Trident, British Naval Policy Since 1945 (1987) and The Future of Sea Power (1990). He lectures worldwide on naval history and maritime security and appears frequently on radio and television. He is a Fellow of the Royal Historical Society.   Dr Peter Caddick-Adams is a lecturer in the Department of Management and Security of Cranfield University. His published work includes The Fight for Iraq (2004) the official British Army pictorial account of the 2nd Gulf War, chapters in By God They Can Fight! (1995) and over 100 entries for The Oxford Companion to Military History (2001).  Since May 1999, he has lectured atCranfieldUniversity on military history and media operations. He has led over 200 visits to more than 50 battlefields around the world.  He joined the Territorial Army in 1985 and currently serves as a military media advisor in the rank of major.   James Holland read history at the University of Durham.  He is a prolific author whose works of history include Fortress Malta: An Island Under Siege 1940 – 1943Italy’s Sorrow; The Battle of Britain and Dambusters – The Race to Smash the Dams.  His fiction includes five novels in the WW2 Jack Tanner series.  He wrote and presented well received television documentaries on the Battle of Britain and, in 2013, the siege of Malta.  He also supports tours around many of the Second World War battlegrounds including the Blitzkrieg in the West, th eBattle of the Bulge, North Africa, Italy and the Fall of Berlin.  He is the Co-Chair and Programme Director of the Chalke Valley History Festival. The chairman: Paul Stoddart served in the RAF as an aerosystems engineer officer from 1983 to 1991.  After a brief career as a journalist on a car magazine he joined the Ministry of Defence in which he has worked in a variety of programme management and analysis posts.  He has written a number of articles on a range of aviation issues including the potential of the Spitfire as an escort fighter.  He is a Fellow of the RAeS and a committee member of the Society’s Air Power Group.  

Art and Actuality

The 1955 film ‘The Dambusters’ uses artistic licence in two main areas.  It unavoidably simplifies a complex story but it is also less than strictly accurate in certain areas so as to heighten the drama.  In the latter case, it gives the impression that the notion of attacking the dams in the German industrial heartland of the Ruhr Valley was solely devised by Barnes Wallis. Wallis did propose breaching the dams and he conceived and developed the ‘bouncing bomb’ (actually a depth charge or mine released with back spin to extend its range). The film also suggests that Wallis faced considerable and unwarranted scepticism from officialdom.  In fact, the Air Ministry (the political-administrative centre of the RAF) had identified the importance of the dams in a 1937 assessment of Germany’s economy.  Specifically, the Air Targets Sub-Committee proposed attacks on the Mohne and Sorpe dams correctly identifying them as the two most important dams in the control of water for the Ruhr’s industry.  That assessment was counter-balanced by the understanding that the weapons available at the time were inadequate to breach such massive structures (the RAF’s standard bomb was a mere 500lb). The ‘bouncing bomb’ (code named Upkeep) required accurate placement with a margin of error of no more than a few yards.  In 1941, an assessment of Bomber Command’s accuracy (the Butt Report) concluded that of aircraft reporting bombing the assigned target, overall only one in three was within five miles of the aiming point.  For targets in the heavily defended Ruhr, the figure was one in ten. Another study estimated that for medium level bombing in daylight, 9,070 bombs would be required to achieve a 90% probability of a hit on a 100 ft x 60 ft (30m x 20m) target. Some scepticism of the accuracy required for successful use of Upkeep was understandable in such circumstances.

Tim Robinson
17 May 2013