A SPECIAL THREE-PART HISTORY of the RAF's brilliant attack on the Ruhr Dams in May 1943, immortalised by the film The Dambusters. These articles have been written on the basis of interviews and released official British and German documents, arid particularly on the private papers and diaries of Barnes Wallis -- the British scientist who invented the unique "bouncing bomb" that smashed the dams.
Picture: David Irving interviews Sir Arthur Harris in 1962
The Night the Dams Burst
by David Irving
First published as a serial in The Sunday Express, London, May 1973
Chapter One: In which Mr Barnes Wallis fights for acceptance of his revolutionary new weapon but then sees it fail its tests
HIRTY-NINE MILE an hour, I makes it," said the plain-clothes policeman. He ponderously opened his notebook and eyed the watch in his hand.
The white-haired driver of the small black Wolseley Ten saloon blinked at him absently from behind metal-rimmed spectacles.
"By Jove, was I really doing that, officer? My mind must have been miles away."
Mr Barnes Wallis looked at his own watch anxiously: it was half-past eleven, and at noon he had to be at the Vickers building in Westminster. But here he was, still in Putney Vale.
"I am on urgent business, officer -- Government business. It's top secret," he stammered.
The policeman grunted, unimpressed. "Really?" he said, licked his thumb, and turned over a new page in his notebook. Wallis groaned. He knew that he was carrying a top-secret film and that he should have an armed RAF guard with him. But this morning the instructions to report to London had come too suddenly for that.
Just two hours before, Sir Charles Craven, the Chairman and Managing Director of Vickers-Armstrong, had telephoned him at his drawing-office near Weybridge, and ordered him to come up to town at once: "The First Sea Lord wants to see your film of 'Highball'," he said. "The one you dropped at Chesil Beach."
To cap it all, just as he had been leaving the Vickers Works, the works foreman had run out and told him that a crack had been found in a Wellington bomber's spar, and it needed an urgent decision. Barnes Wallis was the famous aircraft's designer. That had delayed him for a good half hour. And now this.
"Can I see your driving licence, Sir?" Wallis fumed. He was deceptively mild-mannered, slight in build, and with innocent grey-blue eyes behind those metal frames. Keeping the Sea Lords waiting was one thing, but he dreaded the wrath of Sir Charles: Commander Sir Charles Worthington Craven was a powerful man, and Barnes Wallis had more than once fallen foul of him in his long career.
He was nearly half an hour late when he finally stumbled into the private cinema in the Vickers company's headquarters building in Westminster, clutching the precious reel of film under one arm. Four or five admirals were standing around, shifting from one foot to another in extreme impatience. Admiral Sir Dudley Pound, the First Sea Lord was talking to Craven, and Wallis could see that the glowering Vickers chairman was not in a benign mood towards aircraft engineers today.
What saved Wallis from Sir Charles now was the amazing film he had brought with him.
Onto the screen flickered a title: "Most Secret Trial Number One." Then the camera's telescopic lens focused onto the dark shape of a Wellington bomber, flying low over the waves just off shore.
"That's Chesil Beach," explained Wallis. "Now -- watch that bulge hanging beneath the plane ..."
The bulge was a large black ball, about four feet six inches in diameter. It was obviously spinning backwards at high speed. A light flashed in the cockpit, and the steel ball dropped towards the sea.
That was when the surprises began. Not only did this strange heavy ball fall much more slowly than seemed normal, but when it struck the sea it bounced -- it bounced not once but twelve or thirteen times, with Wallis jubilantly counting each bounce out aloud. It had bounded about half a mile along the sea's surface before it finally ploughed into a wave and sank.
"That's it!" announced Wallis. "That bomb answers most of the problems facing the Air Force today. Dropped at high altitude over Germany, it will float down much more slowly -- so it can be dropped from further outside the range of specially defended targets. Used as a naval weapon, it will bounce over any of the booms and torpedo nets that the enemy at present uses to protect his warships at anchor -- and his huge dams." He chuckled, like a conjurer who has just pulled off a particularly pleasing trick. "And," he said, "when it strikes a battleship's side, because of its back-spin, it will actually curve inwards beneath the ship's hull as it sinks -- so it can be exploded just where the enemy has never bothered to put any armourplate."
SINKING BATTLESHIPS alone would not win the war. Wallis believed however that there was one operation that just might do that:
he had been fighting for years for one massive attack to be carried out on Germany's most vital dams -- a project he had dubbed "An Engineer's Way to Win the War."
This was typical Barnes Wallis. He was outstandingly capable of thinking up new ideas -- almost all of which met with fierce opposition from officialdom: he probably preferred it that way. When Professor Sir Thomas Merton, one of Winston Churchill's leading scientists, had first been approached by Wallis with the Dambusting bomb idea, his first feeling was, This man's absolutely cracked. But, he later told me, "after Wallis had been there for half an hour, I realised that I was talking to one of the greatest engineering geniuses of the world's history."
Much of Wallis's wartime genius had been applied to ball-shaped things. Once he had written to a newspaper that he could design a cricket-ball which would put both sides "out" twice in a day, and would be indistinguishable from a standard ball. The Cricket Club secretaries had persuaded him in anguish not to proceed with the idea.
What Wallis had in mind for the four-ton ball he called "Upkeep" was not cricket.
"There are five dams in the Ruhr. gentlemen," he told the admirals. "Without them, Germany's power -- stations can't make steam, her canals will either overflow or run dry and her most vital factories will be devastated by flooding. One dam, in particular, regulates the supply of the only sulphur-free water available to the Ruhr's steelworks. Do you know, it takes over 100 tons of water to make one ton of steel? This dam, the Moehne Dam, holds back 134,000 tons of water...
He continued enthusiastically, "I and my staff have shown -- we have tried it out on model dams -- that even with a charge as small as 6,500 pounds of RDX explosive, we can destroy the Moehne Dam, the biggest of the five, provided that the explosion occurs in actual contact with the masonry.
"My bouncing bomb will do just that. Just as the naval version will curve underneath the enemy's warship, so the dambusting weapon, over seven times as heavy, will curve in towards the dam-wall as it sinks and cling to it all the way down until the charge goes off."
The admirals had not come to listen to talk of attacking dams -- they wanted to
sink the German Navy, and in particular the Tirpitz. If Wallis's theory was right, the bomb need be no bigger than could fit snugly into the twin-engined Mosquito bomber's bomb bay. This was just what they needed.
After the film show, Air Marshal John Linnell, the Controller of Research and Development at the Ministry of Aircraft Production -- and one of Wallis's most determined opponents -- grudgingly agreed to lend him two of the precious Mosquitoes for trials of the anti -- Tirpitz bomb. Furthermore, at ten o'clock on the following morning, the local boss of Vickers, Major Kilner, rang Wallis breathlessly from London: "The Admiralty have given us the go-ahead! Two hundred and fifty of the Highball bombs are to be put in hand -- top priority -- at once."
WALLIS WAS NOT OVERJOYED. It was good news, but still only a very low rung on a tall ladder. Sinking battleships would not win wars in the way that the sudden destruction of all Germany's most important dams might.
As he put the phone down, Wallis also realised that once the weapon had been used against the Tirpitz, all hope of surprise in using it against the dams would be lost. He had to bring immediate and equal priority to the attack on the dams, and the only way to do that was to get the Prime Minister interested.
This in turn would mean winning Lord Cherwell, the physicist and politician who exploited his friendship with Mr Churchill to such devastating effect, for the cause.
Superficially, Cherwell and Barnes Wallis were similar: both shunned drink and tobacco, and both were extreme vegetarians. But there the similarity ended. The Prof., as Cherwell was known in Churchill's intimate circle, was ruthless in manner and Central European in aspect; Barnes Wallis was the typical English country parson's son -- self-effacing and slight. Above all, Cherwell was an eminent theoretical scientist, whose career had begun in the universities of Darmstadt and Berlin, while Wallis was an engineer who had started humbly as an apprentice in a shipyard at a wage of four shillings per week.
All in all, Wallis did not rate his chances of interesting Winston Churchill too highly. He had had a discouraging experience with Cherwell -- then still Professor Lindemann -- in 1940, and the last time he had called to see him he had been left waiting in an ante-room for two hours while numbers of young men wafted in and out and assured him that "their Prof." would be back from lunch any moment now. On that occasion, Cherwell had crushed him with the words, "You know, Mr Wallis, we don't think these dams are very interesting as targets."
Perhaps Wallis did not know it, but the hostility was not personally directed against him, but another product of the now famous behind-the-scenes Whitehall feud between Cherwell and Sir Henry Tizard, whose position as senior scientific advisor he had usurped. Tizard had backed the Dams Bomb project all along, and made no secret of it; he had promoted it in letters to the ministries, and to Mr Churchill himself. Above all, it was Tizard who had obtained for Wallis permission from the National Physical Laboratory at Teddington to carry out a series of spectacular model-scale experiments with two-inch steel balls catapulted down the length of the laboratory's experimental model-ship tank.
This time, Wallis would not repeat his 1940 mistake. He wrote Lord Cherwell a letter. With the letter he sent a twenty-page secret report, complete with photographs and diagrams; working from facts provided by an officer of the Secret Service, he proved beyond doubt the importance of the five major Ruhr Dams, and explained the whole theory of the spinning bomb -- its aerodynamic and hydrodynamic effects.
Wallis had even found proof of the invention two centuries earlier of a gun able to fire round corners using precisely the same principle; the intrepid eighteenth-century inventor had demonstrated his weapon before an audience at the Royal Society, a body of which Lord Cherwell was now himself a prominent member.
"Unfortunately," explained Barnes Wallis in his letter to the Professor, "the possibilities of this new weapon against naval targets appear to have overshadowed the question of the destruction of the major German dams." If the consequent delay in developing the four-ton dambusting weapon known as "Upkeep" lasted any longer, he said, the whole plan would have to be shelved for a year.
"Large-scale experiments carried out against similar dams in Wales have shown that it is possible to destroy the German dams if the attack is made at a time when these are full of water." In practice that would mean May -- mid-May since the moon would also have to be full. It was now already the end of January 1943.
His present orders were to develop within the next six weeks the anti-Tirpitz bomb, "Highball", for the Mosquito. Given equal priority, he promised that he could do a similar job on the Dams Bomb for the Lancaster Bomber: "Two months," was the promise that he wrote in his letter.
Two days later, on 2 February 1943, he followed the letter up with a personal visit to Lord Cherwell and showed him the film of the Wellington bomber trials two weeks before. With sinking heart, he watched Lord Cherwell's face: no spark of enthusiasm could be seen. In fact, among the papers of the late Lord Cherwell which I have reviewed, there is no indication that Churchill's scientific adviser took any action whatsoever after Wallis's visit.
FOR A WHILE the Upkeep bomb project stagnated.
Wallis was moving in a jungle peopled by opponents and apathetic civil servants; frequently it was impossible to tell the one from the other. David Pye, the Director of Scientific Research at the Air Ministry and also chairman of a committee that had been set up in 1940 to study the possibilities of attacking the German dams, was one of the shrewdest of Wallis's opponents -- always seeming to help, without quite doing so. Later on the same day as Wallis's visit to Lord Cherwell, he was with Pye.
Pye said: "You've got our authority to proceed with design work for the installations of the bomb and its gear in the Lancaster." Wallis, with long experience of civil service methods, demanded: "Can I have that confirmed in writing? And I shall need a full set of the Lancaster's drawings sent down to me ..." "Ah, that's a different matter," snorted Pye. "The Lancaster's one of our most secret planes, and the blueprints are not being shown to anybody."
Wallis sighed. He would have to pull still more strings -- and he was running out of them. Besides, he needed the bombers themselves, not just the blueprints. Within a few days, all that he had been given was the vague promise of the loan of a Lancaster, but on 19 February 1943 bureaucracy dealt him another blow.
Air Marshall Linnell telephoned him, and with a clear note of triumph in his voice ordered him to stop work on the Dams Bomb.
It had been decided that there was to be no further action on it. Wallis again felt himself without friends. Dr Baker, the elderly superintendent of the ship tank at Teddington laboratory, mercilessly told him, "Stop playing the fool and go and do something useful for the war ... "
That evening, Wallis had a private call from Flight Lieutenant Green, his liaison officer to the Ministry of Aircraft Production. Green confirmed his fears. In his diary, Wallis wrote: "Green says that DSR [David Pye] having ensured CRD's [Air Marshal Linnell's] refusal now pretends to back the scheme."
A few days later, injury was added to insult: a brown paper envelope arrived, and Wallis learned that he had been fined two pounds for the speeding offence in Putney Vale, despite a written plea by MIS to the Magistrate, that Wallis was working on the most urgent Government business.
Wallis swallowed his pride, and asked Dr Baker to let him prepare one final experiment in the lab's busy ship-testing tank. This was one experiment which would make the most hard-boiled civil servant sit up and take notice.
He built a model dam across the water tank, and catapulted the two-inch balls at it. A girl cinematographer submerged in an airtight glass tank filmed the spinning spheres as they struck the dam and sank. Wallis showed the film to the Air Staff -- there were audible gasps as the submerged camera showed the spinning balls "cling" to the model dam's face as they sank. There were louder gasps when Wallis showed them and some admirals an even more spectacular experiment in the tank at Teddington: he had moored a large model ship across the tank to represent the Tirpitz. On a signal from him, the assistant fired the first two-inch steel ball. It streaked down the tank, struck the model ship and sank, still spinning, out of sight -- to reappear suddenly on the other side of the ship, having passed right beneath the model's hull.
"I think I have made my point," said Wallis quietly.
He was able to show film of this experiment to Sir Charles Portal and the First Sea Lord on 19 February. Portal was now willing for the RAF to begin planning an attack on the dams but he could imagine what Bomber Command's reaction was likely to be. In fact, he had discovered that Air Chief Marshal Sir Arthur Harris -- "Butcher" Harris -- was hostile to any idea of a dambusting operation. Harris needed every Lancaster he could get for more urgent assignments over Germany, with conventional and trusted weapons like blockbusters and incendiaries. He had run into inventors who thought they had a simple way to win the war before.
As Portal watched the film with Barnes Wallis he thought of the letter he had received that morning from Harris. In it, Harris -- whose private Intelligence "grapevine" was evidently operating at high efficiency -- complained, "All sorts of enthusiasts and panacea-mongers are careering round the Ministry of Aircraft Production suggesting that about thirty Lancasters should be taken off the line and modified to carry a new and revolutionary bomb, which exists only in the imagination of those who conceived it..."
Strictly speaking, that much was true, of course. Barnes Wallis had not yet built, let alone tested, a full-size "Upkeep" rotating bomb. After seeing Wallis's amazing new film, the Chief of Air Staff wrote back to Harris. "I will not allow," Portal promised, "more than three of your precious Lancasters to be diverted." Before he got more, Wallis would have to show that his bomb worked in the full scale. To Wallis, in the meantime, Portal heartlessly offered no words of encouragement at all.
Wallis, independently, decided to tackle the awesome bomber commander Harris himself. He telephoned his chief test pilot, Mutt Summers.
"Mutt," he said, "we'll have to find some way of showing this film to 'Butch' Harris. You know him personally, don't you?"
"Sure, we were in the RFC together."
Summers rang up Harris's deputy, Air Vice-Marshal Sir Robert Saundby. A trip to the RAF Bomber Command headquarters outside High Wycombe was arranged.
Once more Wallis stowed his precious films into the back of his Wolseley, and this time he sat "Mutt" Summers in the front. Together they drove to High Wycombe on the afternoon of 22 February. As he was shown into Harris's office the air chief marshal glowered. "Now what the hell is it that you want?" he rasped. "I won't have you damned inventors wasting all my time!"
Barnes Wallis was unaware of Harris's unflattering remarks about him in his letter to Portal. But Harris's aversion to all inventors was understandable. As a fighter pilot at Northolt outside London, in the First World War, he had been plagued by them and any one of them might willingly have been his downfall. Several legends surrounded this. One inventor had shown him a grapnel, and proposed that Harris should sling it out at the Zeppelin airships wreaking havoc in English towns at that time. Harris had bluntly replied, "My aircraft's horsepower is 80, the Zeppelin's is 1600. Before I start hooking my plane onto a Zepp, I shall want to know who is going home with whom!"
Undeterred, that inventor had reappeared at Harris's airfield with the thing in a suitcase, which he set down on the ground. He said, "I've got it now," he said. "I've put a small explosive charge on it. All you do is press this" -- and the rest of the sentence was abbreviated by a shattering roar as the suitcase blew up of its own accord.
"I HAVE AN IDEA for a bomb," began Barnes Wallis now, blinking short-sightedly at Harris and groping for his spectacles. "A bomb which will destroy the Moehne Dam."
Harris groaned silently. "I've heard about it," he said. "It's far-fetched."
Wallis mentally noted that Harris had obviously been "very much misinformed re job" (as he wrote in his diary).
He launched into a long technical explanation of the principle of the spectacular weapon and concluded: "...you see, if the bomb has a backspin on it, it will be forced against the dam face all the time it is sinking, and it will explode in contact, just as we require."
Harris was taking more notice now. There was something about this quiet-spoken engineer that separated him from the rest. In any case, the man who had designed the sturdy Wellesley and Wellington bombers could not be ignored. Nodding at the projectionist threading the film into the machine, Harris grunted to Wallis: "If this thing's as good as you say, the fewer people who know about it the better." He turned to his deputy. "Saundby, you work the projector."
In the headquarters cinema, with nobody watching except the two air marshals, Wallis and his test pilot, the top secret films of the underwater antics of the rotating bomb "Upkeep" and the airborne trials of "Highball" off Chesil beach were shown again. No sound was heard except the whirring of the projector. When the lights came on again, Harris's pink-complexioned, puffy face was expressionless. He tossed a letter to Wallis, and said, "You'd better read this."
It was the letter from Sir Portal, requiring Harris to lend three Lancasters to Wallis for the full-scale "Upkeep" trials.
Wallis had no idea of how well he had scored personally with Harris. He could not penetrate the mask of the air marshal's face. As they left, he took Summers's arm and said in relief, "Well, that wasn't too bad after all, was it! "
In fact his troubles were not over. Harris -- impressed though he was -- still refused to withdraw a Lancaster squadron from the front line to train for the dams attack. And at this moment, another force intervened with Wallis -- almost certainly guided by the hand of the shortsighted Air Marshal Linnell who had blocked Upkeep at every stage.
At 10 a.m. on the morning after his face-to-face meeting with Harris, he and "Mutt" Summers were ordered to report to Major Kilner's office at the Vickers works. Kilner unhappily told them that Sir Charles Craven, Vickers's chief executive, had ordered them both to London at once.
At Vickers House, the air was frigid was hostility. "I have been asked to tell you," Craven snapped at Wallis, "that you are to stop your nonsense about destroying dams. I have been officially advised that Mr Wallis of Vickers is making a damn' nuisance of himself. You are wasting the Government's and the firm's time and money -- you are to start working on something useful for once. You are forbidden to work any longer on this absurd bouncing-bomb project."
As a final grotesque outburst, he shouted hysterically at Wallis. "And what happened on the Golf Links at Ulverston?"
To Wallis, the whole row was beyond comprehension, let alone Craven's final cryptic challenge. The slight white-haired engineer looked the powerfully built former naval commander in the eye and said, "Well, Sir, if I'm not serving the best interests of the company and the country, I had better offer you my resignation."
It was coolly said; it was meant; and it was too much.
Sir Charles Craven stood up, and crashed his fist down onto the desk, bellowing, "Mutiny, mutiny, mutiny!"
Barnes Wallis stalked sorrowfully out. In his diary he wrote: "Private interview afterwards with [Major] Kilner, and told him again [am] anxious to go ..."
He lunched at the RAF Club in Piccadilly with the Secret Service officer who had given him such support before, and both recognised that their only hope now was Mr Churchill.
The way through Lord Cherwell was evidently barred. But Mr Churchill was also known to rely extensively on a scientific committee set up earlier in the war by Mr Oliver Lyttelton, and it was to two of this committee's three members, Sir Sydney Barratt and Professor Merton, that Wallis went, in Richmond Terrace, that afternoon, still shaken by the mauling meted out to him by Craven.
The two scientists could see that something out of the ordinary had happened. Wallis answered their questioning looks: "I'm done for," he murmured. "I've resigned from Vickers. The dams plan is off." Barratt, who would later become chairman of the mighty Albright & Wilson chemicals concern, questioned Wallis for ninety minutes on the scientific basis of the case, and then Wallis left for home.
This meeting proved to be the turning point, Mr Churchill called for the papers on "Upkeep" and then, his imagination fired, gave the order for the dams raid to be prepared on top priority. At three o'clock on the afternoon of 26 February, Barnes Wallis's hour of sweet revenge arrived, when he and Craven were summoned to the room of his old enemy, Air Marshal Linnell; Linnell, evidently controlling himself with some difficulty, informed Wallis that the War Cabinet had directed that the development and testing of the dambusting bomb and the modified Lancaster bombers that were to carry it were to proceed at once. Choking with rage, Linnell told Wallis: "The Air Staff have ordered me that you are to be given everything you want." A few days later, Linnell announced his intention of resigning.
MANY YEARS AFTERWARDS Wallis would explain: "Half the joy in life really consists in the fight, not in the subsequent success."
Now his fight against bureaucracy was suddenly and unexpectedly over -- but the result of the long delays was that he had now only just eight weeks left to do the job. As he left Linnell's room, he felt physically sick and lonelier than ever before in his life. They've called my bluff, he thought. And out loud he said, "If only I had somebody to lean on..."
The Director of Technical Development, Norbert Rowe, must have overheard him, for next morning there was a letter in the post at Wallis's drawing office: "Dear Barnes Wallis," it read. "I was so distressed to hear your involuntary exclamation after the meeting yesterday. We Catholics always pray to St Joseph when we are in special difficulty." He enclosed the wording of the prayer, and Wallis was not ashamed to say the prayer every morning for the next two months.
Even now Wallis was not given everything he needed. He had to have two hundred tons of steel billets to make the dies for the manufacture of the perfectly spherical bomb casings. This was refused him, and he had to content himself with designing the "Upkeep" version of the bombs as boilers, and padding them out to the spherical shape with wooden casing, held tightly in place by thick steel bands.
One spectre haunted him -- the spectre of failure. Conference followed conference.
The Avro company's Roy Chadwick, the famous designer of the Lancaster, came to discuss the bomber's modification; Group Captain Sidney Bufton arrived to work out the special bomber tactics to be used; armament experts came, to advise on the design of a pressure detonator (a hydrostatic pistol) robust enough to withstand the bomb's first 300 m.p.h. impact with the water, yet delicate enough to go off when the bomb had sunk precisely thirty feet. Avro's promised to let Wallis have the first of the three experimental Lancasters by the first day of April 1943. Wallis moved in distraction between his secret country-house drawing office in the former Golf Club house at Burhill, the arsenal at Woolwich where the test tombs were being filled, and the experimental dropping grounds. Soon he was working ninety hours a week.
He himself designed and built the powerful calliper arms which were to grip each side of the rotating bomb as it was suspended in the Lancaster's bomb bay. He put to leading Government scientists like Professor Patrick Blackett complex questions like how much time would have to elapse before the waves on the Moehne lake's surface subsided after each bomb's detonation, should one bomb not be enough to breach the dam. On a test rig at Weybridge the four-foot bombs were spun at slowly increasing speeds then suddenly dropped into a specially-prepared pit of grease and sandbags to test the equipment's release action. All seemed to be going well.
On 24 March 1943 "Mutt" Summers drove down to Burhill, bringing a passenger with him in his little Fiat -- a babyfaced Cornishman with smiling eyes and the uniform of an RAF Wing Commander. Summers introduced him:
"This is Gibson -- Guy Gibson."
"Gibson," wrote Wallis in his diary, "is doing the big job." Gibson had already survived doing 173 other "jobs" for Bomber Command, which made him a very rare bird indeed.
Of this first meeting with the bomb's inventor, Gibson himself later wrote:
"He looked around carefully before saying anything, then said abruptly but benignly over his thick spectacles:
Wallis waved a list of names in front of Gibson. Gibson's name was not on it. The upshot was that the young wing commander returned to his special squadron fully informed about the new bomb, and about the low-level tactics his bombers would have to employ, but with no idea as to what kind of target they would be attacking.
INTENSIVE TRAINING began, and soon complaints about low-level flying were cascading into the Bomber Group's headquarters. One angry local mayor said that he had seen motorists actually duck as the black-painted four-engined Lancasters thundered past only 150 feet up. Legend has it that Group HQ wrote back: "Our pilots have now been instructed to show due regard for other road-users..."
Late on 6 April 1943, the first special Lancaster was delivered to Farnborough; its mid-upper gun-turret had been removed, and special modifications had been made to the bomb bay. Now the first "Upkeep" bomb was clamped into position between the callipers, and the hydraulic motor coupled up to test the bomb's spin. That evening Wallis telephoned the RAF's new Controller of Research and Development, and told him that everything was "Okay".
All was ready for the Lancaster to begin the first dropping trials. "We'll try the first drop at about 270 m.p.h.," Wallis told the pilot, Sam Browne, "giving the bomb a backspin of about three hundred revs. Let it go when you are level, at 150 feet."
In confident mood, Barnes Wallis waited behind the little ruined church on the shore at Reculver on the north Kent coast, watching for the Lancaster. Wing Commander Gibson drove up shortly and joined him, both of them shivering in the cold morning wind.
Soon they heard the familiar full-throated roar of Lancaster engines in fine pitch. Dead on time the big bomber appeared out of the low early-morning sun, followed by another Lancaster, slightly higher, carrying a cine-camera to record its progress. The first Lancaster had the bulky Dams Bomb suspended beneath it -- the first that had ever been tested. As the Lancasters neared the white marker-buoys a hundred yards off shore, Wallis began to shout, hopelessly, into the roar of engines, "Sam, Sam, you're too high. You're too high!"
Gibson trained a pair of binoculars onto the bomb itself, chequered black and white and already spinning backwards at great speed. He had never seen anything like it. He wondered what on earth could be the target for such a remarkable device. He saw the bomb slowly detach itself from the Lancaster. "It seemed to hang in the air for a long time before it hit the water with a terrific splash," he wrote.
A plume of water sprang up out of the sea, missing the Lancaster by inches. But instead of bouncing, the bomb lurched briefly out of the boiling cauldron of spray, then sank without trace.
After lunch, a second bomb was dropped, with the bomber much lower than before; this time, the bomb suddenly disintegrated in a shower of wooden staves, steel bands and bolts, the heavy steel cylinder bursting out with such violence that one wooden segment smashed into the Lancaster's tail just above it, and nearly brought the aircraft down.
Sunk deep in thought, Wallis trudged with Gibson back through the shingle to where their cars were parked.
© David Irving 1973