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The 'Dambusters' prepare to attack
16th May 1943: An exclusive excerpt from a new book that reconstructs the whole of 'Operation Chastise' minute by minute
In the middle of March 1943 Squadron Leader Guy Gibson had been quietly transferred from his Lancaster bomber squadron. He and a select group of experienced Lancaster crews were to form 'X Squadron' - so hastily formed it did not yet have a number - and had just a matter of weeks to undertake some secret training.
The main force of RAF Bomber Command were then fully engaged in the Battle of the Ruhr, an attack on the heart of German industry. What became 617 Squadron's contribution to the Battle of the Ruhr was a unique target to be attacked by very special means.
They were to attack the critical hydroelectric power that served the region, by attempting to blow up the dams that provided the power. It was expected that the release of the reservoir water would also do immense damage. And they were to do so by dropping a new weapon, never before used in combat - the bouncing bomb invented by Barnes Wallis.
The bombs would bounce over the nets protecting the dams and, because they were rotating, drive themselves down the wall of the dam until they reached the optimum depth to explode - causing a rupture in the dam wall.
Delivering such bombs called for special techniques. They had to be dropped from exactly 60 feet - determined by the point at which two spotlights shining down from the aircraft intersected. All the time, the illuminated aircraft would fly straight and level into a wall of flak.
The entire operation has been reconstructed by Robert Owen in Breaking The German Dams: A Minute-By-Minute Account Of Operation ‘Chastise’ 16–17 May 1943. This dramatic retelling of the operation is very comprehensive, including many contemporary photographs, amongst them several used in the original briefings. Destined to become the definitive account, this is a fine tribute to all the men involved, truly conveying the epic nature of their undertaking.
The following excerpt covers the briefing that the crews received in the late afternoon of 16th May:
The Tannoy ordered all No.617 Squadron aircrew to the station briefing room on the upper floor of the dining block, across the road from Station Headquarters. The building’s symmetrical front elevation with a projecting central unit and four stone pillars supporting a shallow curved canopy gave it the feel of an Odeon cinema. This impression was continued inside with a large atrium and art deco staircase up to the upper floor.
Entry was only permitted after a rigid inspection of identity cards. Tammy Simpson, Martin’s gunner, recorded,
‘It was the first time I can recall ever being asked to produce my identity card on a squadron.’
Exceptionally, Gibson’s flight engineer John Pulford was not at Scampton for most of the day. He had been granted compassionate leave to attend, in his hometown of Hull, the funeral of his father, who had died on 7 May. Although Pulford had no idea of the target, or that he would be operating that night, he knew details of their training and had seen ‘Upkeep’. This necessitated his having a police escort, causing much consternation to his mother and family who thought him to be in some kind of trouble. He left almost immediately after attending the service to be back at Scampton for final briefing.
Upstairs in the briefing room the aircrew seated themselves on wooden slatted benches at long trestle tables, facing a wall on which was pinned a large map of the UK and Europe, alongside a roll-up projection screen. The assembled group was brought to attention as Cochrane entered, accompanied by Gibson, Whitworth and Wallis. Walking down the central aisle, past the epidiascope used for projecting target photographs, the party made their way to the far end of the room and the crews were seated again.
Gibson began proceedings by announcing that their targets were ‘the great dams of Germany’. He then introduced Wallis who repeated what had been said to some at previous mini- briefings. Using a blackboard and cross-section drawing of the Möhne dam he described clearly and in some detail the development and modus operandi of ‘Upkeep’ and then went on to explain the importance of the reservoirs to German industrial output, notably steel production. At one point he reflected that since the Möhne had been inaugurated by the Kaiser in 1913 it was a ‘good target’.
The following images show the Eder Dam from the perspective of the attackers, illustrating the difficult manoeuvres that the Lancaster aircraft would have to perform, at night and under fire.
After Wallis, Cochrane stood up to address the crews. Exuding confidence that the operation would become successful, ‘I know that this attack will succeed’ and indeed become ‘historic’, he again emphasised the need for the strictest secrecy with regard to the nature of the weapon.
While Cochrane spoke Wallis quietly expressed to Gibson his concerns for the crews: ‘I hope they all come back,’ whilst revealing his continued focus on the engineering aspects of the operation and the final proving of his thesis: ‘I look upon this raid as my last great experiment to see if it can be done on the actual thing.’
Gibson then again outlined the structure of the operation, re-confirming the three waves and their targets. At this point it also appears from the post- raid report that crews of the reserve wave ‘were given individual instructions at briefing which were liable to be amended by R/T or W/T during the sortie’ in respect of their individual reserve targets (Lister, Ennepe, Diemel) and their positions in relation to the Möhne.
At this late stage Wallis’s assistant, Herbert Jeffree, may have intervened to point out that it would be dangerous to return with an ‘Upkeep’ if its fuze had been armed on crossing the enemy coast, since there was no way of disarming it again in the air and that no ‘Upkeeps’ should be returned to base. However, this recollection was subsequently disputed by New Zealander Les Munro, who, as will be seen, flew one of two aircraft to return to Scampton with their weapon.
The weather forecast for the night was good. Home bases would have good conditions with moderate visibility. There would be broken cloud at medium level and broken strato-cumulus over northern Germany, Denmark and the German North Sea coast. Thunderstorms at present further south and over east Germany would die down and there then should be good conditions with moderate to good visibility, as over the rest of Germany, with slight stratocumulus between 2,000 and 3,000 feet over the Frisian Islands and similar over the Ruhr, while in the target area of the dams a north-easterly wind was predicted.
As a further recap W/Cdr Dunn ran over signals procedures, and the formal part of the briefing was concluded at 1808 with the synchronisation of watches. Tammy Simpson recalled:
The briefing . . . was very extensive. Toby [Foxlee, Martin’s other gunner] and I chatted in a low voice as the opportunity arose, and we both agreed it would be a gunner’s paradise for searchlight delousing. The weather forecast was for a very clear moonlight night.
Jim Clay, bomb aimer with F/Lt Les Munro’s crew, noted: ‘Everyone was in high spirits and ready to go.’
Flying Officer (F/O) ‘Hobby’ Hobday, navigator with Australian Les Knight, echoed the same recollection:
‘[This] was a marvellous thing to be on. It was so different from any bombing we had ever done before and much more exciting. We thought it was a great effort.’
Others were perhaps more thoughtful. John Hopgood was overheard by Gibson to say to his crew:
‘The first aircraft to attack the dam will probably catch the gunners with their pants down. But the second to attack won’t be so lucky – and that’s us, fellers.’
The aircrew then split into various groups to review key points. Some gathered round the models, photographs and route maps, checking their memories and last-minute details. Dunn reminded the wireless operators in the three separate waves about their different responsibilities. Crews then headed to their respective messes for the pre-flight meal. As they came out into the early evening light those glancing towards the south-east would have noted the moon rising low over the horizon above Scampton’s main gate.
Cochrane’s comments regarding the need for security following the operation were well-founded. It had been intended for No. 618 Squadron to mount a ‘Highball’ attack against the German battleship Tirpitz within a day of the attack on the dams, but development problems, mainly concerning the Mosquito release gear, would prevent this. Nevertheless, it was hoped that ‘Highball’ might soon become operational for use against units of the German and Italian fleets.
For fear of jeopardising ‘Highball’ or indeed any future ‘Upkeep’ operations, it was imperative that the enemy should learn as little as possible about the weapon, its principle of operation, performance and criteria for release. For these reasons a strict protocol had been devised by Bufton, in conjunction with Saundby of Bomber Command, to safeguard the security of the weapon. Press representatives would not be permitted to quote any information from 5 Group, or its units and aircrew concerned with the operation. All press communiqués would be strictly controlled by the Air Ministry and would adhere to a cover plan already agreed. The story was that the operation employed a mine of great size.
This had been dropped by a number of experienced crews who had been specially selected and trained for the operation, which demanded an extremely high standard of flying and the highest degree of accuracy in dropping the mine sufficiently close to the target to be effective. In the event the crews displayed the greatest skill in executing the operation as planned.
The crews were briefed accordingly to ‘ensure that the highest standard of security is maintained for an indefinite period after Operation “Chastise” has been executed’.
Few foresaw that despite some of the ‘Upkeep’ details being revealed in the 1955 film, the weapon would remain classified until 1962.
This excerpt from Breaking The German Dams: A Minute-By-Minute Account Of Operation ‘Chastise’ 16–17 May 1943 appears by kind permission of Pen & Sword Books Ltd. Copyright remains with the author.
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