A heavy blow of a new kind – eighty years since the Dam Busters’ famous raid
ON Monday 17 May 1943 Sir Archibald Sinclair, the Secretary of State for Air, climbed the steps onto the stage at the Albert Hall in London and announced, “I have got news – great news – for you. Bomber Command, the javelin of our armoury, struck last night a heavy blow of a new kind at the source of German war power.”
He went on to explain the targets were vital to German armament production, that several dams had been destroyed or damaged and praised “those superbly daring and skilful crews who smote the Germans so heavily last night.”
He was referring to the recentlyformed 617 Squadron, and ‘Operation Chastise,’ led by 24-year-old Wing Commander Guy Gibson.
The Royal Air Force in 1937 had drawn up a list of potential targets in Germany that included several major dams such as the Mohne and Eder. However, realising that conventional bombs or torpedoes would have little chance of success due to protective booms and nets in the reservoirs, something more audacious was needed.
Aircraft designer Barnes Wallis believed depth charges could work if exploded up against the dam wall. There was one major flaw – the bomb needed to weigh 30,000 lbs.
A 1/50 scale model of the Mohne dam was built (and survives today) at Garston near Watford and tests gave Wallis hope – he calculated that at a depth of 30 feet a 7,500 lbs bomb would have a very good chance of success.
Wallis then set about finding a way to delay the bomb exploding until the prescribed depth. Additional tests took place in July 1942 at a small disused dam built in the 19th century by the Birmingham Corporation Water Department at Nant-ygro near Rhayader, mid-wales. The dam was one fifth the size of Mohne but ten times larger than the Garston model.
One little-known claim, if true, adds an intriguing dimension to one of the most daring raids on Germany. In order for a bomb to explode, two metal arms have to connect (school physics – a ‘make and break circuit’). Wallis needed to delay the explosion and solved the problem at Swynnerton Royal Ordnance Filling Factory Number 5, a research establishment near Stone, Staffordshire, where the staff filled shells with explosives. Quickly constructed in 1940 the factory employed at its peak 25,000 workers from across Staffordshire.
The solution to an effective delay timer was simple yet typical of the British ingenuity encouraged during the Second World War. The story goes that either Wallis or an assistant purchased from a shop in Eccleshall High Street, not far from Swynnerton, a bag of aniseed sweets (or small ‘gobstoppers’ depending on which version of the story). When one was placed between the two metal contact arms it would either dissolve at a constant rate in water just like it does in your mouth, or at the least if the sweet shattered, it had prevented the initial impact on the water forcing the contact, resulting in an explosion when the two metal arms touched. Whichever option, the pressure of water as the bomb descended the dam wall would ensure the explosion would happen – in theory – at the right depth.
Further tests on ‘bouncing’ bombs in laboratory conditions eventually led to a full sized bomb being dropped off Chesil Beach, Dorset. Despite initial setbacks eventually the bombs were ready, although Wallis, forever the perfectionist, dropped a metaphorical bomb on Guy Gibson: the Lancaster bombers would have to fly at around 60 feet above the water at a constant speed of 240 miles per hour, with the bomb revolving in reverse at 400 rpm to minimise the impact when hitting the water; in the dark; while being shot at. The stoical Gibson pushed his hand-picked crew, relentlessly practicing bombing runs over several British dams including at Uppingham (Rutland) and Derwent (Lake District). The bomber crews were drawn from the RAF, RNZAF, RCAF, RAAF – British and Commonwealth crews taking the fight to Germany. Modifications were made to the bombers, including the removal of upper gun turrets to stabilise the single ‘oil drum’ shaped bomb suspended under the fuselage. Gibson held a final briefing and explained that their targets were the Eder and Mohne dams with Sorpe and Ennepe dams less important targets. At just before 9.30pm on the evening of Sunday 16th May 1943, 19 Lancaster bombers took off from RAF Scampton in Lincolnshire. The first in the air was ‘E for Easy’ flown by RAAF
The bombers would have to fly at 60 feet above the water at a constant speed of 240mph
Flight Lieutenant ‘Norm’ Barlow DFC. Fay Gillon,
a Women’s Auxiliary Air Force intelligence officer was in ‘P for Popsie.’
The day before the raid Gibson had asked for his black retriever, killed in a motoring accident, to be buried outside his office at midnight on the 16th May – when he estimated they would both be going “into the ground”.
The Lancasters flew very low across the Channel, ‘E for Easy’ hit a power cable over Holland and crashed. As the bombers neared their targets the training took over and Lancasters lined up for bombing runs. Gibson released his bombs and three times he accompanied other bombers to draw anti-aircraft
fire. The Eder dam breached in two places and the Mohne dam had one large breach resulting in a tidal wave thirty feet high cascading down the valleys.
When this confirmation was received, Arthur ‘Bomber’ Harris, who had been sceptical about Operation Chastise, said “Wallis, I didn’t believe a word you said when you came to see me. But now you could sell me a pink elephant!”
At the time it was estimated 120,000 civilians were made homeless and 4,000 were killed (the final figure was around 1,600 – mainly foreign slave labour). The ‘tidal wave’ from the Mohne reached 60 miles, and from the Eder 50 miles.
The railway system struggled with refugees. Coal production was disrupted, including the 1,000,000 tons a month sent to Italy, and armaments production such as U-boat engines was affected.
The Mohne dam held 134,000,000 tons of water, the Eder 202,000,000 tons. Some 30,016,000,000 gallons of water was released at Mohne and at Eder 45,248,000,000 gallons (compared to the Thames flow of 2,500,000,000 gallons a day). Nine thousand German engineers were sent to deal with the rescue and repair work.
The attack on the Sorpe dam was not successful, although the structure was weakened. The bombing run had to fly parallel to the dam, rather than towards it. The dam at Ennepe was attacked by ‘O for Orange’ Lancaster which flew so low down a ‘ride’ or fire break in the forest the bomber actually sliced the tops off some of the trees.
Wing Commander Guy Gibson was awarded the Victoria Cross and under the newspaper headline “Flooding Unleashed, Mohne Breached” he declared: “For many weeks we picked Lancaster crews have been training for the operation. They worked in complete secrecy on a bomber station which, so far as possible, was cut off from any contact with the outside world. Only about half a dozen other men in the whole of Bomber Command knew what they were doing.”
Originally known as ‘The Dam Raids’ Operation Chastise became the ‘Dam Busters’ in the 1952 book by Paul Brickhill, followed by “Britain’s favourite war film” in 1955, of the same name.
Derwent dam was used in the film to represent the dams in Germany. Guy Gibson was played by Richard Todd, Barnes Wallis by Michael Redgrave, whom Wallis thought was ‘too good looking to be me.’
And who remembers a certain lager advert of a bouncing towel ‘bomb’ in a hotel pool to the Dam Busters theme, with its by-line “turned out nice again”?
In the 1980s the name of Gibson’s dog was censored, which compromised the authenticity of the film as his name was Gibson’s code that the Mohne dam had been breached.
A film now in the editing stages, ‘Attack on Sorpe Dam,’ will be released this year, based on the first-hand account of the 21-yearold bomb aimer George ‘Johnny’ Johnson, who guided his Lancaster bomber in ten times before he released his bomb above the Sorpe dam, braving the German anti-aircraft fire.
‘Johnny’ Johnson insists he was not a hero: “I was just doing my job.”
Of the 133 crew that flew out, 56 did not return. Eleven Lancasters made it back to RAF Scampton. The bomb in Lancaster ‘E for Easy’ that crashed en route was salvaged and the Germans began working on their ‘Kurt’ jet propelled bomb version. Barnes Wallis advised that the best defence for British dams was to dazzle German pilots with searchlights and use smoke and balloons – poacher turned gamekeeper. The anticipated German attacks did not materialise.
This month is the 80th anniversary of the dams raid. The next time you are in a sweet shop, treat yourself to a packet of aniseed balls or a gobstopper and as you roll it round in your mouth, reflect on what these brave young men and one woman achieved.