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Mr Irving with Sir Arthur HarrisA 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, and 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 in The Sunday Express, London, May 1973



Chapter Two: In which Mr Barnes Wallis gets the special bomb to work, and the raid begins

Chapter One: In which Mr Barnes Wallis fights for acceptance of his revolutionary new weapon but then sees it fail its test
Chapter Three: In which the Ruhr Dams are breached


RITISH INVENTOR extraordinary Barnes Wallis shivered as the sea slowly rose to his neck. I'm getting beyond this sort of thing, he thought.

He and a handful of middle-aged men dressed only in underpants, were slowly edging their way out from the beach. Had anybody else been strolling down that deserted shore in Kent that chilly April evening, it would have been a strange sight that met his eyes.

But there were no onlookers. It was wartime. This was 17 April 1943, and all access roads to this secluded spot had been cordoned off by sentries all day.

Wallis was one of the foremost aeronautical engineers in Britain. The other bathers were leading scientists and civil servants.

"It's no use," sighed Wallis after a while. "We've been looking for hours. The fragments must all be buried far too deep. Let's go back to the Miramar for dinner -- I'm getting cold."

They were looking for the remains of a ball that they had lost -- a four-ton spherical bomb. A low-flying Lancaster bomber had dropped it in the sea, but instead of bouncing along on the surface of the sea, it had exploded and sunk before their eyes.

The bouncing bomb was Wallis's invention -- an invention with which he hoped to destroy the Germans' heavily-guarded power and water supply dams, vital to the Ruhr where most of Germany's heavy industry was concentrated. "An Engineer's Way of Winning the War" was how he had described it.

"I just don't understand it," he said to mathematician Professor Taylor, as he recovered his thick, horn-rimmed spectacles from his pile of clothes and replaced them on his nose. "We gave the bomb the right amount of backspin. We dropped it from the right height, and at the right speed. And yet -- crunch -- it falls to pieces."

He shivered in the cold spring air, as he dried himself on the only thing available, a large pocket handkerchief. He was in no doubt as to the bleak future. The whole operation -- crews, aircraft and bombs -- had to be perfect by 10 May 1943, which was less than four weeks from now. Only then would the moon be full -- and the reservoirs.

For three years he had campaigned for the recognition of his project, and now at last people had listened to him. He had blown-up scale models of dams and shown that his shockwave theory of destroying them held, but only so long as the bombs could be exploded in contact with the dam wall. He had developed small-scale bombs that would bounce over the defences, and cling to the dam wall as they sunk. Colossal sums of money were being invested in the operation now -- not just the 400 his tiny model-dam experiments at the Road Research Laboratory had cost.

Against military and civil-service opposition, Mr Churchill had intervened and ordered the establishment of a special Lancaster bomber squadron, and that unit, No.617 Squadron, was even now training for the one task of destroying the five major Ruhr dams. Twenty-one Lancaster bombers had been taken off the production line at Avro's and drastically modified to carry the special spherical bomb that he, Wallis, had promised would do the trick.

So now there was only one snag: the full-scale bomb was a failure. The first time they had dropped it, a monster steel cylinder padded out to the shape of a sphere with wooden packing, it had burst as soon as it struck the sea. That was no good at all.


 ON THE DAY after their fruitless bathing party, Wallis and the other experts watched three more full -- scale bombs dropped in the English Channel off Reculver by the same Lancaster. Two had been given a special varnish coating, and the third was finished in plain wood. On the first run, the sphere stayed intact but sank immediately, without bouncing. The second bomb burst into fragments, just like the one they had dropped some days before.

Wallis groaned, and steeled himself for the failure of the third.

As the Lancaster roared past this time, something unexpected happened. The bomb hit the sea, and the wooden casing completely disintegrated just as before. But the bare steel cylinder was left, still madly spinning, and this burst out of the tower of spray and hopped quite clearly several times across the sea, covering finally a distance of seven hundred yards.

"The sphere broke up," exclaimed Walls, speaking more to himself than to the others. "But the cylinder ran just as it should have done! It ran!"

He gave orders for full-size bombs to be manufactured keeping the steel cylinder shape, bare of any kind of wooden casing. Early on 22 April, the Lancaster test-dropped one of them off the same deserted beach from a height of 185 feet. This test too was a failure, but Wallis was sure he knew a way of licking the problem. His staff saw him reach for his sliderule and a pad of paper.

Two days later, he met with Wing Commander Guy Gibson, 617 Squadron's commander, and put it to him. "I know this is asking an awful lot," Wallis said hesitantly. "You must tell me at once if it can't be done. Can you bring your planes down to a level sixty feet, instead of 150, and make exactly 232 miles an hour, before you release your bomb?"

Gibson flinched. He thought, If 150 feet is low, then sixty feet is very low. At that height you've only got to hiccup to land in the drink.

But he loyally replied, "We'll have a crack tonight."

When the morning chosen for the final crucial trials dawned, it was pouring with rain and there was a freezing wind. Walls and the Air Ministry experts again crowded the foreshore at Reculver beach.

Just sixty feet up, the black Lancaster bomber roared past them. As the bare steel cylinder dropped from its bomb bay, spinning backwards, and slowly fell towards the sea, Wallis silently prayed.

It struck the sea with a crash -- and emerged from the plume of spray making a gigantic bounce. The bomb bounced, bounced, and bounced again -- each time striding hundreds of yards forward and throwing up huge spouts of water as though an invisible giant was stamping across the sea. Then it settled, and sank from sight.

Wallis had done it!

In his mind's eye, at the moment that his "bouncing bomb" disappeared from view, Barnes Wallis could see a huge masonry wall looming across the horizon, towering up out of the waves -- a wall suddenly rent by blast and collapsing under the weight of millions of tons of water: the Moehne Dam.

Then the others were crowding round him, clapping him on the back and congratulating him. Wallis allowed himself a cautious smile, as he returned to his car.


  ONE TRIAL ALONE was not enough, of course. Other tests followed, to get the speed of the aircraft and the amount of backspin imparted to the bomb just right.

A means had to be found for aircraft to fly at precisely sixty feet over smooth water by night -- an apparently suicidal task. Then someone remembered that a similar problem had been solved by an inventor in the First World War, who had proposed mounting two spotlights underneath a plane, angled so that their beams would only intersect at a certain height. In a surprisingly short space of time the actual apparatus was found gathering dust in a store at Farnborough, and the contraption was adapted for Guy Gibson's squadron.

One day early in May, a Lancaster dropped the first special bomb to be fully charged with its explosive: a huge pillar of water shot up, towering over a thousand feet into the sky. Barnes Wallis's work on the weapon was complete; everything was now up to Gibson and his crews.


At three o'clock on the afternoon of Saturday 15 May, Wallis climbed into a white Wellington aircraft with his Chief Test Pilot "Mutt" Summers and Major Kilner, Vickers' managing director. There was a big Red Cross on the aircraft's sides -- it was the only plane available.

In brooding silence, the little party flew from Vickers' aerodrome at Weybridge up to the operational bomber station at Scampton. No.617 squadron's nineteen specially modified black Lancaster bombers were already waiting at their dispersal areas.

Guy Gibson met Wallis as he climbed down the Wellington's ladder.

"The AOC's just told me we're doing the job tomorrow night, if the weather holds," he said.

Wallis nodded absently, unable to believe that after three years of increasingly frustrating battle against bureaucracy, the day had come when 133 hand-picked RAF officers and men were to stake their lives on the accuracy of his calculations. How could he express his feelings to these men? He was nearly sixty -- they were almost without exception under twenty -- three, carefree -- looking and eager.

Young though they were, their faces wore the battle -- hardened expressions of veterans. All had completed two tours of bomber operations, so there were no greenhorns among them: all had been decorated, and all were experts in their crafts.

At six o'clock, the inventor faced the nineteen captains of aircraft for the first time: chalk in hand, standing on a platform in the almost empty Briefing Hall, he went through the now-familiar explanation of the crucial importance of the Ruhr Dams to Hitler's war industry. As he spoke, Wallis recalled how many times he had appealed for this attack before. What if there were some unconsidered factor even now, which would prove his theories wrong? The effects of gravity in such an enormous structure as the Moehne Dam, for example. It did not bear thinking of.

Wallis finished his lecture. He slowly surveyed the curious faces through his spectacles, and said: "You see, you gentlemen are really carrying out the third of three great experiments: we have tried this out on model dams, and we have tried it out on a dam one-fifth the size of the Moehne. I can't guarantee that it will come off. But I hope it will..."

Giant eight-wheeled trucks were rolling across the airfield as he left the Briefing Hall. Each was laden with the huge cylindrical bombs, covered with tarpaulins and each was still warm from the four tons of special high-explosive cast inside it at Woolwich Arsenal.

In Guy Gibson's crowded office, the final plans were hatched. Code-words had to be arranged, last-minute alterations to the bomber routes worked out. He and Wallis stayed there until well after midnight. This time tomorrow Gibson would already be over the Moehne Dam, and Wallis would know whether his calculations had been correct.


It was far into Sunday morning before Barnes Wallis woke up. It was a balmy, sunny day such as seldom comes in May. He breakfasted late, and spent the afternoon fussing round the special Lancasters. Each crew wanted him to see if their bomb was spinning properly. At mid-day, the last of the special Lancasters arrived, brand -- new from Avro's. Nineteen aircraft and crews were now ready.

At three o'clock, the clattering fingers of the teleprinters at Scampton slammed into the paper roll, repeating a signal from No.5 Bomber Group Headquarters:


And ten minutes later the die was finally cast for that night:


Three hours later, behind locked doors, Wallis again briefed the bomber crews. They looked tired and strained, and small wonder: in two months of intensive training for "Chastise" they had completed nearly two thousand hours of nerve-racking low-level cross-country flight, most of it in darkness.

As they trooped out of the Briefing Hall, Wallis turned to Gibson, his voice choking. "I hope that all come back," he said.

"It won't be your fault if they don't," came the reply.


  GIBSON'S SECOND-IN-COMMAND, twenty-three year old "Hoppy" Hopgood, shouted:

"Hey, Gibby. If you don't come back, can I have your egg tomorrow?"

It was the oldest of the RAF's aircrew gags. It veiled Hopgood's own anxiety: as his crew climbed aboard their Lancaster, he said, "The first aircraft to attack the dam will probably catch the flak gunners with their pants down. But the second to attack won't be so lucky -- and that's us, fellers."

Wallis stood on the airfield and watched as the heavy bomber3, pregnant with his bouncing bombs, lumbered down the runway and lifted into the air. None but the crews knew that this was the real thing. There was not even the usual farewell party of WAAFs and ground crew to wave them off.

Soon the last aircraft had lifted into the moonlight air. Lincolnshire mist rolled across the almost-empty airfield.

Barnes Wallis wandered into the Officers Mess, but his appetite for dinner was almost gone. He wondered how many of these young men would return. By the time he had finished his meal, seven had already died -- obliterated in a sheet of flame as Lancaster K for Kite, flown by Sergeant G.W. Byers, struck the Waddensee lake in Holland, hit by a flak battery based on one of the offshore Dutch islands. He had been flying at three hundred feet instead of the sixty feet ordered, and that probably proved his undoing.

At two minutes past eleven, the first two waves of 617 squadron's bombers swept in across the enemy coast at points widely separated, so as to divide the Luftwaffe fighter forces. As Guy Gibson's own little formation of three Lancasters reached the lakes near Haltern, they ran into an unexpected nest of flak guns. Within seconds, all three aircraft were trapped in a dazzling cone of searchlight beams.

Gibson threw his aircraft to one side and got out unscathed.

Flight Lieutenant Hopgood's M-Mother suddenly shuddered as cannon shell tore into the port wing. Shells exploded in the cockpit, and over the intercom the rest of the crew hears "Hoppy's" flight engineer gasp "Bloody Hell...!"

"Hoppy" had been hit in the face, and blood was streaming out of a wound. He shouted to his engineer grimly, "Don't worry. Hold your handkerchief against it."

He switched on his VHF radio, and called up Gibson: "We've been hit, Sir. But we're carrying on. See you on target."

He checked on his crew one by one: there was no reply from the front gunner.

Gregory must have bought it, he thought.

The aircraft were now flying so low that accidents were bound to happen. One dropped so low over the Zuyder Zee that the bomb suspended beneath its bomb bay was torn off by a wave. Still the remaining aircraft swept on. The noise on the ground must have been deafening.

Flight Lieutenant Hopgood suddenly saw through a cloud of pain that he was heading straight for a line of pylons. He was only sixty feet up, and took a split -- second decision. He pushed his column forwards, and swooped beneath the cables; as the tail of the bomber went up, rear gunner Pilot Officer Tony Burcher thought they had had it. He saw the shadows of the cables whip across the top of his turret, and then the danger was past.

The leader of the second wave, Flight Lieutenant Bill Astell, lost his way soon after midnight: it was only for a fraction of a second, but that was long enough to kill him. After crossing a canal he had to turn south briefly to try to find a landmark, and he was shot down almost at once by machine-gunners on Gilze-Rijen airfield. Out of control, his B-Baker crashed into a block of barracks on the airfield's edge and blew up in a slow red glare that momentarily swelled to light up the whole sky. The other Lancaster crews saw the clouds of smoke, but these faded into the distance until they were out of sight of the rest of the formation.

In G-George, Wing Commander Guy Gibson threw a glance at his watch. Quarter past midnight. "Well, boys, I suppose we had better start the ball rolling!"

He meant it literally. The flight engineer flicked a switch, and with gathering momentum the special bomb suspended between powerful calliper jaws in the bomb bay began to revolve. A few minutes later, the flight engineer reported: "Five hundred revs, Sir."

Gibson switched on his transmitter: "All aircraft switch over to radio -- telephone control."

Ahead of him he could see the Ruhr hills coming towards them. He lifted the Lancaster up and cleared them with feet to spare. There was a shout from his bomb-aimer.

"We're there!"

There ahead of them was the Moehne lake, and at its far end, silhouetted against the moonlight, was the Dam, 2,100 feet long. The lake was so full that its parapet barely showed above the water's mirrorlike surface.

"Good God -- can we break that?" gasped Gibson.

The Moehne Dam looked like an enormous, angry and impregnable battleship, with its low freeboard and two stone towers. The battleship was firing a broadside at them from twelve or fifteen guns, and there were more guns on the lake's north shore. The deadly onionstrings of tracer fire streamed across the lake, aimlessly as yet because the aircraft were hard to see and echoes were reverberating from every hill.

Gibson called up each of his force's Lancasters in turn. All but Bill Astell reported in. Astell had been dead twenty-five minutes by now.

"Hullo all Cooler aircraft. I'm going in to attack. Stand by to come in to attack in your order when I tell you..."

It was precisely twenty-eight minutes past midnight. Gibson brought his Lancaster round, and dived over the woods fringing the lake. His bomb aimer "Spam" Spafford shouted, "You're going to hit those trees."

"That's all right, Spam -- I'm just getting my height."

His navigator Terry Taerum switched on the two spotlights. This was when things could get really dangerous. He watched the two short lines projected onto the lake just in front of the plane. They were still some way apart.

"Down ... down ... down..." he directed.

Gibson shifted in his seat nervously, as water came up toward the thundering plane. "That's it!" came Terry's voice. "Steady now."

They were just sixty feet up. Spam clicked the bomb's fusing switches into the "On" position.

A mile ahead of them, one of the German gunners shouted, "They've switched on their landing lights! They must be mad!"

A hail of fire swept out from the crest of the dam, converging on the advancing aircraft. Crouched behind his controls, Gibson thought In another twenty seconds we shall all be dead.

Spafford cried out, "Bomb gone!"

The black cylinder slipped out of its clamps. The bomber lurched upwards as its load fell away. The bomb struck the lake, bounced once ... twice ... three times, covering hundreds of yards with each enormous bound. The weapon slammed into the dam's parapet, right between the valve towers -- a magnificent shot. The bomb ricocheted backwards, and sank into the lake.

The seconds began to tick away.

Gibson's wireless operator had fired a red Verey cartridge as they crossed the dam. As the flare soared up into the sky, there was a colossal explosion and a column of water and spray mushroomed up into the sky, towering a thousand feet above the dam. It was the most fantastic spectacle they had ever seen -- this silver column of water, lit a lurid red on one side by the red signal flare.

But the dam was still holding.

Gibson ordered his wireless operator to signal back to England using the prearranged code that they had released the special bomb; that it had exploded only five yards from the dam; and that the dam had not been broken.


Shortly before midnight, a large black saloon car swept up to the guardroom at No.5 Group's headquarters at Grantham. The driver flashed special recognition lamps at the sentries, and they stood back and allowed the car to pass at once.

This was Air Chief Marshal Sir Arthur Harris, Commander in Chief of Bomber Command -- otherwise known as "Butcher" Harris.

He strode into the Headquarters Operations Room. Barnes Wallis was already there. He had been driven over from the Scampton airfield an hour before.

"Any news yet?" barked Harris.

"Apart from an early flak warning from Gibson there's nothing at all," answered Air Vice-Marshal Cochrane, the Group commander. "But they should be attacking at any moment."

One of the room's long walls was dominated by a blackboard listing the bombers taking part. On a dais running along the opposite wall sat the operations officers, in telephone contact with the wireless room. Barnes Wallis had long ceased pacing up and down, and was now sitting in a dejected heap on the little staircase leading up to the dais.

Harris joined the Group commander at the other end of the room, underneath the map of Europe.

Suddenly there was a shout.

"There's a signal just coming through, Sir." The Chief Signals Officer had a telephone to his ear. "It's from Wing Commander Gibson:

GONER-bomb exploded five yards from dam, no apparent breach."

He waited. Then he added: "That's all."

So Gibson's bomb had been correctly placed, but the dam was still standing. An icy chill gripped Wallis: all those lives, he thought. He buried his head in his hands; out of the corner of his eye he could see the two air marshals at the far end of the room, and there was a clearly perceptible look of vexation invading "Butcher" Harris's puffy features.


  ALONE IN THE 6,000-kilowatt powerhouse below the Moehne Dam, there was a look of fear on 52-year-old foreman Clemens Koehler's face. Now there was no doubt at all! The British were attacking his dam.

A look-out on the Bismarck Tower had raised the alarm at twenty minutes past midnight, just as the first Lancaster had begun circling the lake. At first the small but wiry foreman had not been afraid -- air-raid warnings were not uncommon in the Ruhr by 1943.

But suddenly something clicked in his mind: tonight there was a full moon, and the RAF did not normally venture over the Ruhr on moonlight nights. And tonight the lake's level was higher than it had ever been before.

Soon his fears were confirmed. The British bombers were not droning past high overhead -- they were swarming like stray bees around the distant end of his lake, and one was coming nearer.

Koehler's hand reached for the telephone. With trembling fingers he dialled the number of the United Electricity Company of Westphalia offices in Nierderense and Neheim -- the little towns just down the valley. The noise of aircraft engines was very loud now. Hoarse with fear, he shouted: "This time they are attacking the dam!" The voice at the other end was sleepy at first, and downright disbelieving. Koehler slammed the phone down, and ran for the door.

As he tore the door open, he caught the sound of the guns on both towers firing wildly and then Guy Gibson's Lancaster thundered over him, barely a hundred feet up, the whole valley vibrating to the roar of its four Rolls-Royce Merlin engines. A huge explosion tore at Koehler's lungs, and water cascaded over the top of the dam.

Drenched to the skin, Koehler began to run -- he ran as he had never run before until he had reached the side of the valley hundreds of yards away; and then flopped down underneath a larch-tree half-way up the slopes. He turned round, and gazed as though hypnotised at the enormous dam wall's moonlit face. It was still not cracked.


  GIBSON WAS RADIOING the second of his aircraft to go into the attack.

"Hello, M-Mother. Make your attack now. Good luck!"

"Hoppy" Hopgood, his face numb from loss of blood, grunted: "Okay, attacking."

Over his aircraft intercom he ordered: "Stand by, rear gunner. They're putting up a terrific barrage ahead."

Facing rearwards, Pilot Officer Tony Burcher, M-Mother's rear gunner, couldn't see much. He moistened his lips and watched the lake surface coming up towards his turret. Streams of tracer and cannon-shell flashed past his turret on either side as the Lancaster raced in towards the dam. He swung his turret round onto the beam, ready to open fire on the dam's gunners as soon as they came into his field of fire. The front gunner is not firing, Burcher noticed. He must be dead already.

He could hear the navigator's voice telling the pilot to take her down lower -- and then lower still.

Suddenly there was a Whummph, and sparks and flames streamed past Burcher's turret.

"Christ! We're on fire! "shouted the flight engineer.

"Feather Number Two" ordered Hopgood. The startled bomb-aimer released the special bomb about a fifth of a second too late -- bounding across the lake, it smashed into the parapet of the dam and blew up in a vivid yellow flash.

"Prepare to abandon aircraft!" That was Hoppy's voice. Burcher desperately tried to swing his turret round to the fore-and-aft position, but the hydraulics were powered by a pick-up on the port-inner engine, and that engine was a mass of flames.

The turret wouldn't budge. I'm trapped. His parachute pack was hanging inside the fuselage, and he could not get at it until the turret was fore-and-aft. Parachute! What use was a parachute at zero feet?

Like a man possessed he began to crank the Dead Man's Handle, slowly inching the turret round by hand.

Mopping the blood away from his eyes, the Lancaster's commander "Hoppy" Hopgood clung grimly to his controls with his free hand. But the plane was losing power and he could not gain much height. He knew he would never get out alive himself. But there was a last service he could perform for his crew, and he did it: he banked the Lancaster round to the right, away from the valley which was doomed to be drowned.


  GIBSON'S OTHER CREWS had seen the red Verey cartridge fired by Hopgood's radio operator Sergeant Minchin as the bomb went. Now they were transfixed by the horrifying sight of the Lancaster flown by Flight Lieutenant Hopgood, the gentle English boy they had all come to like so well, plunging on into the night, streaming a growing plume of flame.

Burcher was inside the fuselage by now, struggling to strap on his parachute.

The rear hatch flew open, and he saw that Minchin had opened it. The radio operator had dragged himself along the fuselage, his right leg shot away. Burcher could have jumped out now, but he grabbed Minchin's own chute and fastened it properly onto the white-faced, dying man. Then he hurled him out of the plane. He held on to Minchin's D-ring, but he did not see any chute opening.

Still in the plane, Burcher pulled his own ripcord and bundled as much of the silk parachute under his arm as he could. Then, in one final mechanical act -- the act of an officer exceptionally well drilled -- he plugged his intercom into the socket by the rear hatch and gasped, "Rear gunner, abandoning ship now!"

He heard Hoppy scream, "For Christ's sake, get out of here!"

They were the last words Hopgood ever -spoke. M-Mother erupted in a sheet of flame as the flames reached back to the main-wing fuel tanks. Burcher was blasted up into the air, his back broken by the bomber's tail-fin. Less than two hundred feet below, the ground rushed up to meet him, and a painful darkness enveloped his consciousness.





NEXT CHAPTER: in which the dams are breached


© David Irving 1973

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