Chastise: The Dambusters Story 1943

Almost four years after Britain chose to go to war, and eighteen months after America found itself obliged to do so, the bulk of their respective armies continued to train at home, preparing for an invasion of the continent for which no date had been set. The Royal Navy and the Royal Canadian Navy, assisted by the Ultra codebreakers and latterly by the US Navy, had performed prodigies to achieve dominance over Dönitz’s U-Boats: the Atlantic sea link was now relatively secure, and a vast tonnage of new shipping was pouring forth from American shipyards. But this was a defensive victory, its importance more apparent to Allied warlords than to Churchill’s and Roosevelt’s peoples.

Among the latter, even after its North African successes the standing of the British Army remained low: memories lingered, of so many 1940–42 defeats in Europe, North Africa and the Far East. Many Americans viewed their Anglo-Saxon ally with a disdain not far off contempt. A July 1942 Office of War Information survey invited people to say which nation they thought was trying hardest to win the war. A loyal 37 per cent answered, the US; 30 per cent named Russia; 14 per cent China; 13 per cent offered no opinion. Just 6 per cent identified the British as the hardest triers. ‘All the old animosities against the British have been revived,’ wrote an OWI analyst. ‘She didn’t pay her war debts for the past war. She refuses to grant India the very freedom she claims to be fighting for. She is holding a vast army in England to protect the homeland, while her outposts are lost to the enemy … Phrases such as “The British always expect someone to pull their chestnuts out of the fire” and “England will fight to the last Frenchman” have attained considerable currency.’

Thoughtful British people saw that in almost three years since Dunkirk in June 1940 their army had accomplished relatively little, while the Russians endured the most terrible and costly experiences in the history of war. In 1942 Winston Churchill’s reputation as a war leader fell to its lowest ebb, in the face of new British humiliations. The sister of RAF pilot John Hopgood, a future dambuster, was an ATS officer who wrote to her mother in August that she had been cheered by the proclaimed success of the recent Dieppe raid: ‘the feeling that at last we were taking the offensive and that my uniform would mean something. A feeling I had very strongly at the beginning of the war, but it has gradually diminished since we have been on the defensive. This is not the talk of a defeatist, but I think it is the truth which most of us have experienced lately. I hope that [Dieppe] was a dress rehearsal and that the performance [D-Day in France] will follow shortly.’ Which, of course, it did not.

Belated successes in North Africa delivered Churchill from a real threat of eviction from his post as minister of defence. It was plain that the German flood tide on the Eastern Front was ebbing; that the Russians had survived the decisive crisis of their struggle. But the British people had seen little about their own war effort in which to take pride since the RAF’s sublime triumph in the 1940 Battle of Britain. An unusually reflective young airman afterwards looked back upon an early-1943 conversation with friends: ‘It was pleasant to sit there and rest a while and think that the worst was behind … The evening had been pleasant and we had practically “won” the war. But we wouldn’t have been so pleased if we had known of the big battles that were to be fought; the heavy casualties to be borne … The tide had turned, but it was a leap year tide.’ This was Guy Gibson, who in those days led 106 Squadron of the RAF’s Bomber Command.

It is hard to overstate the impatience felt by millions on both sides of the Atlantic for action against Hitler on a scale to match the efforts and sacrifices of ‘Uncle Joe’ Stalin’s Red Army. The Western Allied leadership was prosecuting the war at a pace that suited themselves, their countries’ immunity from invasion from 1941 onwards conferring the luxury of choice, such as the Russians never had, about where and when to engage the Wehrmacht. British caution exasperated US chief of the army George Marshall and his peers. Yet the old prime minister and his chiefs of staff recognised fundamental truths: that Britain and America were sea powers, confronting a great land power. It would be madness to attempt an amphibious return to the continent without command of the air, which could not be secured any time soon. The voice of Churchill, backed by the intellects of his professional military advisers, Portal and Alanbrooke foremost among them, was decisive in delaying D-Day until June 1944, saving hundreds of thousands of American and British lives. Meanwhile, it was vital to the prestige and morale of the Western Allies, and especially those of Churchill’s nation, that Britain should be seen to be carrying the war to Germany by any and every means within its power.

2 HARRIS

A consequence of the Western Allies’ cautious grand strategy, rendered necessary by their slow industrial build-up, was that the Anglo-American air forces, and especially heavy bombers, constituted their most conspicuous military contribution to the defeat of Germany between the fall of France in June 1940 and the invasion of Normandy. Bomber Command’s pre-war estate of twenty-seven British airfields had by 1943 expanded to over a hundred stations, while the RAF’s overall strength grew from 175,692 personnel to over a million men, including a significant proportion of the nation’s best-educated adolescents.

Some senior officers, including the USAAF’s Gen. Carl ‘Tooey’ Spaatz and Air Chief Marshal Sir Arthur Harris, C-in-C of Bomber Command, believed that air attack on Germany could render redundant a land invasion of the continent. 1943 was the year in which British warmakers drafted plans for Operation Rankin, whereby troops would stage an unopposed deployment to occupy Germany in the event that some combination of bombing, Russian victories and an internal political upheaval precipitated the collapse of the Nazi regime, an abrupt enemy surrender.

Yet, while Winston Churchill committed a lion’s portion of Britain’s industrial effort to the air offensive, he never shared the airmen’s extravagant hopes for it. For a season in 1940, when Britain’s circumstances were desperate, he professed to do so. Once the threat of invasion receded, however, he recognised that, while bombing could importantly weaken the German war machine, it could not hope to avert the necessity for a continental land campaign. The airmen’s most critical contribution until June 1944 was to show Churchill’s people, together with the Americans and – more important still – the embattled Russians, that Britain was carrying the war to the enemy. The prime minister recognised, as his chiefs of staff often did not, the value of ‘military theatre’ – conspicuous displays of activity that sustained an appearance of momentum, even when real attainments were modest. As the author has written elsewhere: ‘There must be action, even if not always useful; there must be successes, even if overstated or even imagined; there must be glory, even if undeserved.’ Through those apparently interminable years between Dunkirk and D-Day, again and again the BBC prominently featured in its news bulletins the words ‘Last night aircraft of Bomber Command …’ followed by a roll call of industrial targets attacked in France, Italy, and above all Germany.

In 1940–41 the RAF caused mild embarrassment to the Nazi leadership, which had promised to secure the Reich against such intrusions. Bombing nonetheless inflicted negligible damage upon Hitler’s war effort. Although more aircraft became available during the winter of 1941, poor weather, navigational difficulties and German fighters inflicted punitive casualties upon the attackers, who still made little impact on the enemy below. Thereafter, however, a succession of events took place which progressively transformed the offensive.

In December 1941 the prime minister and the Air Ministry received an independent report from the Cabinet Office, commissioned by Churchill’s personal scientific adviser Lord Cherwell, the former Professor Frederick Lindemann, analysing the effectiveness of British bombing through a study of aiming-point photographs returned by aircrew. This devastating document showed that the average RAF crew on an average night was incapable of identifying any target smaller than a city. In consequence, and after a vexed debate in which practical issues dominated and moral ones did not feature at all, British strategy changed. By a decision for which Cherwell was prime mover in concord with Air Chief Marshal Sir Charles Portal, since October 1940 head of the air force, it was agreed that instead of pursuing largely vain efforts to locate power stations, factories and military installations, the RAF would assault entire urban regions.

The principal objective would be to ‘de-house’ and frankly terrorise the German industrial workforce – break the spirit of Hitler’s people – even though the Luftwaffe had conspicuously failed to achieve this against Churchill’s nation. The new policy, known as ‘area bombing’, was never directly avowed to the public, nor indeed to Bomber Command aircrew, who were told that the RAF continued to strike at military and industrial targets, with civilian casualties an incidental, and implicitly regrettable, by-product. This was a falsehood. Between 1942 and 1945, the civilian population of Hitler’s cities was the target of most British bombing.

America’s entry into the war in December 1941 made eventual Allied victory seem certain. Until a continental land campaign began, US air chiefs were as eager as their British counterparts to demonstrate their service’s war-winning capabilities. Daylight operations by American B-17 Flying Fortresses and B-24 Liberators began slowly to reinforce the RAF’s night campaign. The British received early deliveries of a new generation of four-engined heavy bombers – Short Stirlings and Handley-Page Halifaxes, followed by Avro Lancasters – which progressively increased Bomber Command’s striking power. They also acquired ‘Gee’, the first of a succession of electronic aids which improved the accuracy of RAF navigation.

Finally, in February 1942 Sir Arthur Harris became commander-in-chief of Bomber Command. Britain’s inter-service wrangles and clashes of personality inflicted less damage than did those of the United States, and for that matter Germany, upon their own war efforts. They nonetheless absorbed time and energy. The Royal Navy and the RAF disliked and distrusted each other as a matter of course, rivals for resources in an ongoing struggle in which both were frequently rebuked by the prime minister. Many airmen also viewed soldiers with the disdain due to their serial record of defeats.

Harris became the most intemperate squabbler. He regarded with contempt Special Operations Executive, the covert warfare organisation for which a handful of bombers was grudgingly committed to drop arms to the Resistance in Occupied Europe. As for sailors, it was one of his favourite sayings that the three things one should never take on a boat were an umbrella, a wheelbarrow and a naval officer. He fought like a tiger against the diversion of heavy aircraft to support the Battle of the Atlantic, arguing that it was a far more economical use of force to bomb U-Boats in their German construction yards than to waste flying hours searching for them in the vast reaches of the oceans. He described the RAF’s Coastal Command as ‘an obstacle to victory’, despite the importance of its Very Long Range Liberator squadrons in countering U-Boats. Meanwhile the admirals, who had a good case in pleading for more aircraft, spoilt this by insisting that Bomber Command should repeatedly attack the Germans’ concrete submarine pens on the north-west French coast, which were invulnerable to conventional bombs, and heavily defended by flak and fighters.

Harris waged a further ongoing struggle with the Air Ministry, of which much would be seen in the debate about Germany’s dams. The C-in-C of Bomber Command was an elemental force, single-minded in his conviction that he, and he alone, could contrive the defeat of Nazism through the systematic, progressive destruction of Germany’s cities. Alan Brooke, chief of the British Army, recorded characteristic Harris testimony at a chiefs of staff meeting: ‘According to him the only reason why the Russian army has succeeded in advancing is due to the results of the bomber offensive! According to him … we are all preventing him from winning the war. If Bomber Command was left to itself it would make much shorter work of it all!’

Freeman Dyson, a brilliant young scientist who spent much of the war in the Operational Research section of Bomber Command at High Wycombe, characterised his chief as a ‘typical example of a prescientific military man … brutal and unimaginative’. Hyperbole was this glowering figure’s first choice of weapon in exchanges with those who crossed him. This became a kind of madness, and Harris a kind of madman, but in the unwelcome predicament of Britain for much of the Second World War, Churchill recognised that such a figure had important uses. Horace Walpole wrote in the mid-eighteenth century: ‘No great country was ever saved by good men, because good men will not go to the lengths that may be necessary.’

Though Harris became the foremost exponent of ‘area bombing’, which has ever since been inseparably identified with his name, he was not its begetter, merely its obsessive implementer. It was widely believed, especially by soldiers and sailors, that Bomber Command’s C-in-C achieved an intimacy with Churchill, by exploiting the proximity of Chequers to his headquarters at High Wycombe, to secure support for his purposes. This view seems unfounded. The prime minister after the war described the airman as ‘a considerable commander’. He rightly judged that Harris instilled in the bomber offensive a dynamic, a sense of purpose, which it had previously lacked. He valued the airman’s skilful exploitation of public relations, conspicuously manifested in his May–June 1942 ‘Thousand Bomber raids’, of which the most famous, or notorious, was directed against Cologne.

Yet the prime minister never much liked ‘Bert’ Harris – as he was known to intimates. ‘There was a certain coarseness about him,’ Churchill observed, implicitly contrasting the airman, who set no store by social graces, with such officers as Sir Harold Alexander, a gentleman in every respect, who became Churchill’s favourite general. Harris, just short of fifty when he assumed command, was the son of an engineer in the Indian Civil Service. He spent much of his youth in southern Africa, and especially Rhodesia, which he came to love. The reverse of the coin of his force of character was a vulgarity of language and behaviour, exemplified by his observation that Britain’s generals would take tanks seriously only ‘when they learned to eat hay and fart’.

He experienced a lunatic moment in January 1943, when he became so incensed by the incidence of venereal disease among aircrew that he issued an edict, without consultation, that every diagnosed sufferer should be obliged to restart from scratch his tour of thirty ‘trips’ to Germany. This monstrous threat, rooted in a notion that shirkers were inviting infection in order to escape from operations, was withdrawn only in June, following the intervention of Sir Archibald Sinclair, Secretary of State for Air, who overruled the C-in-C.

Nonetheless, at a time when many others to whom Churchill entrusted high commands – for instance Dill, Wavell, Auchinleck – had proved weak vessels, despite their impeccable manners, Harris, a four-letter man in the eyes of most of his peers, possessed qualities that the prime minister valued. He said long afterwards of Bomber Command’s chieftain, in conversation with his last private secretary: ‘I admired his determination and his technical ability. He was very determined and very persuasive on his own theme. And the Prof. [Lord Cherwell] backed him up. You must remember that for a long time we had no other means than Bomber Command of hitting back. The public demanded action and rejoiced at our counter-blows at German cities after Coventry and so many other towns … Large numbers of German aircraft and vast resources of manpower and material were tied up in their air defence.’

Harris’s personal life was unorthodox. His recreation was driving ponies: he had been known to take the reins of his own trap to travel to Chequers to see the prime minister; if called upon, he could manage a four-horse team. His wife Barbara walked out on him in 1934, securing a contested divorce on grounds of his adultery. Thereafter, their three children as well as herself were ruthlessly written out of the script of his life, and even out of his subsequent official biography. Not long afterwards he proposed marriage, down the intercom of a Hornet Moth biplane in Rhodesia, to a very young woman to whom he was giving a joyride. ‘I think it would be very nice if you were to marry me – will you?’ Harris demanded of Polly Brooks, who – in P.G. Wodehouse’s phrase – turned him down like a blanket. Miss Brooks offered the reasonable excuse that the airman was old enough to be her father, though she added politely, ‘It’s very nice of you to ask me.’

Instead, in 1938 he married another very young woman, twenty-three-year-old Therese Hearne, a strong-minded Catholic always known as Jill, who gave birth to a daughter, Jackie, the following year. Thus, through the years during which Harris directed Britain’s bomber offensive from his High Wycombe headquarters, at his official residence in nearby Springfield House a wife more than twenty years his junior entertained a procession of Allied warlords while rearing a small child.

Conflict was Harris’s environment of choice, his feuds tempered only by a harsh wit. He once scrawled on a memorandum describing complex alternative means of destroying a target: ‘TRY FERRETS’. He enjoyed the joke against himself of being stopped for speeding in his Bentley – an offence which he revelled in repeating – and rebuked by a policeman who told him that he might have killed someone. ‘Young man,’ the air marshal replied, albeit surely apocryphally, ‘I kill thousands of people every night!’ His staff and close associates were unable to decide whether the chronic ulcers from which he suffered stimulated his ill-temper, or were precipitated by it.

During the year since the new C-in-C assumed direction of Britain’s strategic air offensive, he had transformed Bomber Command from a transport service dumping ordnance almost indiscriminately around the German countryside into a serious weapon of war. Sceptics, some of them within the RAF, sustained doubts about whether burning cities was doing anything like as much as Harris claimed to advance Allied victory. Sir Wilfred Freeman, Portal’s able vice-chief, wrote to the CAS on 16 September 1942 deploring the grossly exaggerated claims made by some commanders: ‘in their efforts to attract the limelight, they sometimes exaggerate and even falsify facts. The worst offender is C-in-C Bomber Command.’

Nonetheless, the RAF’s publicity machine made much of ‘Bomber’ Harris, as he was nicknamed by the press, and of the devastation that his aircraft inflicted nightly upon Germany. In 1940 Bomber Command dropped just 13,033 tons of bombs on enemy territory; in 1941, 31,704 tons. Thereafter, under Harris’s command, in 1942, 45,561 tons fell; in 1943, 157,457 tons; in 1944, 525,718 tons. By the war’s end, Bomber Command was capable of raining upon Hitler’s people in a single twenty-four-hour period as many bombs as the Luftwaffe dropped during the course of its entire 1940–41 blitz on Britain.

Autocratic is an inadequate word to describe Harris’s style of command. He considered himself to have been entrusted with a vast responsibility, and resisted any interference, criticism or even interrogation about his manner of fulfilling this. He regarded with contempt the Directorate of Bomber Operations, a cell within the Air Ministry which provided Portal with in-house advice that often ran counter to the convictions of Harris and his staff, few of whom dared to think for themselves, far less speak out. He especially loathed Gp. Capt. Syd Bufton, who had successfully championed the 1942 creation of an elite Pathfinder force – what became Bomber Command’s No. 8 Group – against the opposition of the C-in-C. ‘Morning, Bufton,’ he once greeted that officer on arriving at the Air Ministry for a meeting. ‘And what have you done to impede the war effort today?’

Among the terms of abuse Harris heaped upon his critics, that of ‘panacea merchant’ was intended to be the rudest, embracing Bufton, sometimes Portal, even the prime minister. The words meant that a given individual was advocating means of defeating the Axis, or more especially of bombing Germany, which did not require the systematic demolition of its urban centres. The relationship between Harris and Portal was extraordinary. Bomber Command’s C-in-C frequently defied direct instructions from the Air Ministry, and sometimes from Portal himself, to divert aircraft from attacking cities towards alternative objectives, of which dams came to be among the most contemptuously regarded, alongside ball-bearing factories, V-weapon sites, French railways, synthetic-oil plants, aircraft factories and U-Boat pens.

The head of the RAF was subjected to barrages of invective from his nominal subordinate, to which he was often driven to respond in the language of a headmaster rebuking an errant pupil. In April 1943 there was a characteristic Harris explosion, about a pamphlet circulating widely in British cities and allegedly also at some bomber stations, headed ‘STOP BOMBING CIVILIANS’, together with a demand from the C-in-C for the identification and indictment for treason of its authors, essentially for highlighting inconvenient truths.

Portal replied on the 9th: ‘It does not appear that prosecution of the authors for circulating [this pamphlet] among civilians would have the slightest chance of success. No court would be likely to hold that it was an offence to advocate that bombing should be confined as far as possible to military objectives. You suggest that this pamphlet comes under the heading of subversion when addressed to an individual in the Service. Even if this is technically correct I do not think it would be prudent to maintain in public that a pamphlet such as this, maintaining a moderately-worded statement of the case against civilian bombing, is likely to incite aircrew to disobey orders … We can however reduce the likelihood of such opinions gaining ground by emphasizing in our publicity industrial damage rather than the destruction of civilian dwellings.’ The RAF’s chief of staff replied to another incontinent note from the C-in-C of Bomber Command: ‘I feel bound to tell you frankly that I do not regard it as either a credit to your intelligence or a contribution to winning the war. It is in my opinion wrong in both tone and substance.’

How did Harris retain his job until 1945, when he displayed an unreason and insubordination that few other senior officers would have dared to indulge? He possessed in full measure the quality of ‘grip’ indispensable to successful commanders in war. Propaganda elevated Harris into a famous figure, and such people become ever harder to sack. He was a man of steel, certain of his purposes when many others, including Portal, wavered and doubted about how the air offensive should best be conducted. ‘Peter’ Portal, as he was known to intimates, possessed an intellect unusual among service officers of any rank, including chiefs of staff. He was a brilliant diplomat, especially in conducting relations with the Americans, whom Harris privately regarded with contempt. But he was also often indecisive. Portal did not oppose area bombing, indeed presided over its inception. He merely favoured leavening fire-raising attacks on cities with precision strikes whenever suitable targets could be identified, and means found to hit them.

Nobody in high places was sufficiently assured of the superior merit of any alternative strategy, or of any more effective commander at High Wycombe, to remove Harris. Later in the war, extraordinary though it may seem when hundreds of bombers continued to fly forth nightly to broadcast death and destruction, the prime minister lost interest in the air offensive: it is striking how little mention Bomber Command receives in the final volumes of Churchill’s memoirs. Once the great land campaigns got under way, armies and the fate of nations entirely eclipsed air forces as the focus of his attention. In the early months of 1943, however, Harris was near the zenith of his fame and importance. He was playing a role more conspicuous than that of any other British commander towards encompassing the destruction of Nazism. Without Harris, without Bomber Command, until June 1944 there would have been only Gen. Sir Bernard Montgomery and his Eighth Army, the North African and thereafter Italian ‘sideshows’.

In January 1943, when President Franklin Roosevelt and the US chiefs of staff met Churchill and the British chiefs in newly liberated Casablanca, the British achieved one of their last diplomatic triumphs of the war, before American dominance of policy and strategy became explicit. The US team unwillingly accepted that there would be no Western Allied invasion of north-west Europe that year. Instead, there would be amphibious assaults on Sicily and probably thereafter Italy, together with a ‘combined bomber offensive’ on Germany by the two air forces. The consequent so-called Casablanca Directive ordered British and American air chiefs: ‘Your primary aim 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.’

In the event, no ‘combined’ offensive took place; instead, there was a competition between the US and British air forces. Sir Arthur Harris paid mere lip service to Casablanca’s emphasis on refined targeting. His aircraft continued to heap fire and destruction on Germany’s cities by night, while in daylight the USAAF claimed to pursue precision bombing of identified weak points in the Nazi war economy. Because, in reality, American bombing proved highly imprecise, especially in poor weather, hapless German civilians saw little distinction between the rival strategies. Moreover, intelligence about enemy industry remained a weakness of the strategic air offensive from beginning to end.

In February 1943, Harris stood on the brink of a new campaign to deploy almost the entire resources of his Command against the industrial cities of north-west Germany, which would become known as the Battle of the Ruhr. The enthusiasm of others – within the Ministry of Economic Warfare, the Air Ministry, the Admiralty and even Downing Street – for more selective targeting roused his scorn. Portal, Bufton and some other airmen regarded extremely seriously the Casablanca Directive: they strove to identify and attack choke points in the German industrial machine. Any such proposals, however, encountered savage resistance from Harris’s headquarters at High Wycombe to the diversion of aircraft from ‘area bombing’. Until the last weeks before Guy Gibson and his men set forth on what would become the most applauded operation of Bomber Command’s five-year campaign, its commander-in-chief wanted ‘his’ aircraft, ‘his’ offensive, to have nothing to do with it.

3 THE ‘PANACEA MERCHANTS’

As far back as October 1937, RAF planners identified Germany’s water resources – dams and reservoirs – as a vulnerability in the Nazi industrial machine. Bomber Command initially focused on nineteen Ruhr power stations and twenty-six coking plants, which its staff believed could be destroyed by three thousand bombing sorties. This would allegedly bring Nazi war production to a standstill, in return for an anticipated loss of 176 British aircraft. Then the Air Targets Sub-Committee of Major Desmond Morton’s Industrial Intelligence Centre took a hand, highlighting the dependence of electricity generation, mining and coking activities upon water supply. Morton’s cell urged that the mere breaching of two dams, the Möhne and the nearby Sorpe, could achieve the desired outcome, a prospective war-winner, for far less expenditure of effort.

It was meaningless, however, for planners to focus upon any target system unless means existed to attack it, which they certainly then did not. Destruction of the Möhne, composed of almost a million cubic feet of masonry, was admitted to be ‘highly problematic’ at a time when the RAF’s heaviest aircraft, the Heyford, carried only 500-lb bombs. In March 1938 it was agreed that the significance of the dams made it worth exploring ‘newly-developed weapons’ with which they might be attacked. But, as the engineer Barnes Wallis often later complained, while the RAF was doctrinally committed to strategic bombing, its planners gave negligible attention to the ballistic challenges involved in the demolition of large structures.

Britain’s airmen were imbued with a faith that the mere fact of subjecting an enemy nation to bombing would cause its people, and even perhaps its industrial plant, to crumble before them. ‘In air operations against production,’ wrote Gp. Capt. John Slessor, a future head of the RAF, in 1936, ‘the weight of attack will invariably fall upon a vitally important, and not by nature very amenable, section of the community – the industrial workers, whose morale and sticking power cannot be expected to equal that of the disciplined soldier.’ The intention of Britain’s airmen to play a decisive and independent role in achieving victory over Germany relied for fulfilment more on expectations of the havoc that terrorisation of civilians would wreak than on any rational analysis of the weight of attack necessary to cripple the Nazi industrial machine.

In the cases of the Möhne and the Sorpe, experts at the Air Ministry’s research department at Woolwich warned: ‘If the policy to attack dams is accepted, the [Ordnance] Committee are of the opinion that the development of a propelled piercing bomb of high capacity would be essential to ensure the requisite velocity and flight … Even then its success would be highly problematical.’ Subsequent debate concluded that, given the low standard of aiming accuracy achieved by RAF bomber pilots in peacetime, before they were even exposed to enemy fire, a successful attack on Germany’s dams was impracticable.

Yet British planners continued to nurse this dream, which was mirrored by a German nightmare. On the eve of war, 29 August 1939, Justus Dillgardt, chairman of the Ruhrtalsperenverein organisation responsible for regional water resources, suggested that a succession of bombs exploded sub-aquatically within a hundred feet of the base of his dams, the effects multiplied by the water mass – a scientific phenomenon identified by the British only three years later – might prompt dam collapses. If the Möhne was breached, Dillgardt warned that ‘this entire industrial area … would be completely paralysed … not only would the population of four to five millions be without water, but all mines and coking plants would suddenly cease work owing to lack of industrial water supply’.

Through the early war years, both the Air Staff and British economic warfare researchers sustained enthusiasm for striking at the enemy’s water resources. The Ruhr and its industries accounted for a quarter of the Reich’s entire consumption, much of this derived from the Möhne reservoir. The Air Targets Sub-Committee was told that its destruction would create ‘enormous damage’, affecting hydro-generating stations. The ‘low-lying Ruhr valley would be flooded, so that railways, important bridges, pumping stations and industrial chemical plants would be rendered inoperative’.

In June 1940, amid the crisis of the fall of France, Bomber Command groped for means of striking back at the victorious Nazis. Its senior air staff officer, Gp. Capt. Norman Bottomley, again urged the merit of breaching enemy dams. On 3 July, Portal, then Bomber Command’s C-in-C, wrote to the Air Ministry pinpointing a key target. Surely, he said, ‘the time has arrived when we should make arrangements for the destruction of the Möhne Dam … I am given to understand that almost all the industrial activity of the Ruhr depends upon [it].’ He suggested a possible torpedo attack by Hampden bombers, or high-level bombing attack against the ‘dry’ side of the Möhne’s wall.

But what realistic prospect could there be of such an operation’s success? Throughout the wars of the twentieth century, again and again it was shown that strategy must follow technology, and also required mass, whether in the matter of landing-craft for amphibious operations; radar to negate prime minister Stanley Baldwin’s warning – correct when it was delivered in 1932 – that ‘the bomber will always get through’; or attacks on German dams. It was useless to identify a purpose unless means to fulfil it existed, or might be created, as they certainly could not have been in 1940, when Bomber Command was weak, and Britain’s war effort was focused upon averting defeat.

The weapons available to pursue the airmen’s ambitions remained inadequate in quality as well as quantity. The Hampden bombers mentioned by Portal could carry nothing like heavy enough ordnance to dent, far less breach, the Möhne. A December 1940 study of German bombing of the UK concluded, a trifle ungrammatically: ‘comparison of the Results … with that obtained by [RAF] General Purpose bombs against similar enemy targets left no doubt as to the inefficiency of our bombs’. GP bombs contained too little explosive, yet until the end of the war Britain’s airmen continued to risk and sacrifice their lives to drop more than half a million of them. The 4,000-lb HC – High-Capacity – bombs introduced in 1941, and known to aircrew as ‘cookies’, were relatively efficient wreckers of urban areas: sixty-eight thousand were dropped in the course of the offensive. They were useless, however, against such huge structures as dams.

It was noted that during the Spanish Civil War, Nationalist forces with direct access to the Ordunte and Burguillo dams had failed in attempts to destroy them, using charges laid by hand. Winston Churchill urged the American people: ‘Give us the tools and we will finish the job.’ Where, now, were to be found tools such as might collapse the enemy’s dams? The Deputy Chief of Air Staff responded to Portal’s proposal to target the Möhne that to breach its concrete mass would require dropping a barrage of a hundred mines on the reservoir side, together with a huge bomb exploded on the ‘dry’ side. ‘The practical difficulties of this method are considered to be insuperable at present.’

The great dams of north-west Germany possess a beauty unusual among industrial artefacts, a majesty enhanced by their settings among hills and woodlands. They were created in the early twentieth century, to meet soaring demand for water from both a rising population and burgeoning regional heavy industries. Work on building the Möhne, then the largest structure of its kind in Europe, began in 1908, part of a construction marathon undertaken by the Kaiserreich in the decade before the First World War. Completed in 1913 at a cost of 23.5 million marks, it was opened by Wilhelm II. The flooding of its reservoir, which eventually held almost five thousand million cubic feet of water, interrupted the Möhne river, which flowed west into the Ruhr.

The new lake, the Möhnesee, displaced seven hundred rural inhabitants of the Sauerland. It became a focus of national pride, and also a tourist attraction. Floatplanes and pleasure craft plied its waters between the wars, as they did likewise on its near neighbour the Sorpetalsperre, constructed between 1926 and 1935 in the Sorpe river valley below the village of Langscheid. A narrow-gauge railway carried more than 300,000 tons of material to what became Europe’s largest construction site, where an earthen embankment was raised around a masonry core. On completion, this rose 226 feet above the river, and was 2,297 feet in length. Its lake held 2,520 million cubic feet of water.

The Eder, forty-five miles south-eastwards in Hesse, was a smaller structure, 157 feet high and 1,312 feet wide, damming the Eder river two miles from the towering old castle of Waldeck to create a reservoir seventeen miles long, holding just over seven thousand million cubic feet of water. It was another pre-World War I project, opened in 1914, and quite unrelated to the Ruhr system. The Nazis stocked all their big reservoirs with quantities of fish, especially pike and carp, as a strategic resource in anticipation of falling sea catches when hostilities began.

The German dams, and especially the Möhne, retained their fascination for British air and economic intelligence officers through the early war years. Many and many were the hours that experts pored over photographs and technical reports about wall thicknesses, surrounding topography, defences. W/Cdr. C.R. Finch-Noyes of the Government Research Department at Shrewsbury examined all available studies and assessments, and on 2 September 1940 reported that if ten tons of explosive could be detonated beneath the Möhne’s wall, ‘there seems a probability that the dam would go’. He suggested that if aircraft flying at 80 mph and very low altitude released a succession of one-ton units close to dams, natural momentum would propel them across the water to the walls, where they would sink, to be detonated by hydrostatic pistols. This was a fascinating notion, because it anticipated – quite unknowingly – Barnes Wallis’s ‘bouncing bomb’, in truth a depth-charge. Finch-Noyes indeed urged that a standard British naval depth-charge might fulfil the requirement. One of his old colleagues, a strange, erratic air pioneer named Noel Pemberton-Billing, suggested that the dam might be attacked using a ‘hydroplane-skimmer’ that would jump over its buoyed net defences.