B
THE DAMS RAID
617 Squadron was formed by Wing Commander Guy Gibson on 21 March 1943 from selected crews in 5 Group and the squadron trained for 6 weeks for the special operation. 19 Lancasters were dispatched in 3 waves, each aircraft armed with the special “bouncing bomb” developed by Barnes Wallis for attacking German dams. The entire operation was to be carried out at low level to escape attack from German night fighters and to release the bombs just above the water in the dams.
One aircraft had to return early after it struck the sea a glancing blow which tore off its bomb. 5 further aircraft were shot down or crashed before reaching their targets and one was so badly damaged by Flak that it had to turn back. Thins left 12 Lancasters available to bomb the dams. Wing Commander Gibson's aircraft and 4 other crews bombed the Mohne Dam and breached it despite intense fire from light Flak defending the dam. 3 aircraft went on to bomb the Eder Dam, which was also breached. 2 aircraft bombed the Sorpe Dam and 1 the Schwelme Dam but without causing breaches in their walls. The twelfth surviving aircraft could not find its target in misty conditions and returned to England without dropping its bomb. 3 further Lancasters were shot down after they had bombed.
Total casualties were 8 aircraft out of the 19 dispatched. It is estimated that 4 were shot down by light Flak, i crashed after being damaged by the explosion of its own bomb, 2 crashed after hitting electricity cables and i after striking a tree when its pilot was dazzled by a searchlight. Of the 56 crew members in these planes, 53 were killed and only 3 became prisoners of war, 2 of them being badly injured. For his leadership of this amazing operation and for his courage in attacking Flak positions at the Mohne Dam after having carried out his own bombing run, Wing Commander Gibson was awarded the Victoria Cross. 34 other men received decorations.
The breaching of the Mohne and Eder Dams were major achievements. The Mohne reservoir contained nearly 140 million tons of water and was the major source of supply for the industrial Ruhr 20 miles away. The water released caused widespread flooding and disruption of rail, road and canal communications and of the supply of electricity and water. The water-supply network was particularly affected by the silting up of pumping stations by the flood water. It is not possible to state the effect of all this upon industrial production in precise terms but there was certainly some disruption and water rationing was in force until the winter rains came and filled the reservoirs again.
The Eder was even larger than the Mohne, containing 210 million tons of water, but it was 6o miles from the Ruhr. The city of Kassel, 25 miles away, and the inland waterway system in the Kassel area, were more affected by the attack on the Eder than was the Ruhr area. The German view is that, if the aircraft which were allocated to the Eder had been switched to the Sorpe Dam, the effect upon the Ruhr's industrial production would have been extremely serious, but the Sorpe's construction was of a nature which made it a difficult target for the Wallis bomb, hence its low priority in the raid. The Sorpe reservoir just managed to keep the Ruhr supplied with water until the Mohne Dam was repaired.
The number of people drowned has been calculated at 1,294, most of them near the Mohne Dam. The town of Neheim-Husten, which was situated 5 miles down-stream of the Mohne Dam, took the full impact of the flood and at least 859 people died there. By one of those tragedies which periodically struck foreign workers and prisoners of war whose camps were near targets in Germany, 493 foreigners - mostly Ukrainian women land workers - died in their camp at Neheim-Husten. It is believed that 58 or more of the dead were around the Eder Dam. The total number of dead - as quoted at 1,294 - was a new record for a raid on Germany, easily exceeding the 693 people killed at Dortmund in a raid earlier in May in which 596 aircraft took part!
617 ORB SummaryMinor Operations
9 Mosquitoes to Berlin, Cologne, Dusseldorf and Munster, 54 aircraft minelaying off Biscay ports and in the Frisians, 4 OTU sorties. 1 Wellington minelayer lost.
6 Bomber Group May 16/17, 1943
27 Wellingtons from 426, 428, 429, and 431 Squadrons were ordered on a mining operation to the Frisian Islands and St. Nazaire. The crews were over the garden at between 700 and 6,000 feet, sowing 52@1500 lb mines. Richard Koval (6bombergroup.ca)
Events
The aircraft (AJ-B) was piloted by Flight Lieutenant "Bill" Astell DFC. It crashed (it hit an electricity pylon) close to Marbeck, Germany 
at 00:15 on 17 May 1944 en route to the Moehne Dam as part of the first wave attack of operation CHASTISE, the attack on the German Dams.
Canadians Pilot Officer FA Wile, Flight Sergeant FA Garbas and Warrant Officer Class2 A Garshowitz, and four RAF members of the crew (Flight Lieutenant W Astell DFC, Sergeants I Kinnear, R Bolitho, and Flying Officer D Hopkinson) were all killed.
Operation Chastise, commonly known as the Dambusters Raid was an attack on German dams carried out on the night of 16/17 May 1943 by 617 Squadron RAF Bomber Command, later called the Dam Busters, using special "bouncing bombs" developed by Barnes Wallis. The Möhne and Edersee dams were breached, causing catastrophic flooding of the Ruhr valley and of villages in the Eder valley; the Sorpe Dam sustained only minor damage. Two hydroelectric power stations were destroyed and several more damaged. Factories and mines were also damaged and destroyed. An estimated 1,600 civilians " about 600 Germans and 1,000 enslaved labourers, mainly Soviet " were killed by the flooding. Despite rapid repairs by the Germans, production did not return to normal until September. The RAF lost 53 aircrew killed and 3 captured, with 8 aircraft destroyed.
The mission grew out of a concept for a bomb designed by Barnes Wallis, assistant chief designer at Vickers.Wallis had worked on the Vickers Wellesley and Vickers Wellington bombers and while working on the Vickers Windsor, he had also begun work, with Admiralty support, on an anti-shipping bomb, although dam destruction was soon considered. At first, Wallis wanted to drop a 10 long tons (22,000 lb; 10,000 kg) bomb from an altitude of about 40,000 ft (12,000 m), part of the earthquake bomb concept. No bomber aircraft was capable of flying at such an altitude or of carrying such a heavy bomb and although Wallis proposed the six-engined Victory Bomber for this purpose this was rejected. Wallis realized that a much smaller explosive charge would suffice if it exploded against the dam wall under the water but German reservoir dams were protected by heavy torpedo nets to prevent an explosive device from travelling through the water.
Wallis devised a 9,000 lb (4,100 kg) bomb (more accurately, a mine) in the shape of a cylinder, equivalent to a very large depth charge armed with a hydrostatic fuse, designed to be given a backspin of 500 rpm. Dropped at 60 ft (18 m) and 240 mph (390 km/h) from the release point, the mine would skip across the surface of the water before hitting the dam wall as its forward speed ceased. Initially the backspin was intended to increase the range of the mine but it was later realized that it would cause the mine, after submerging, to run down the side of the dam towards its base, thus maximising the explosive effect against the dam.[7] This weapon was code-named Upkeep.
Testing of the concept included blowing up a scale model dam at the Building Research Establishment, Watford, in May 1942 and then the breaching of the disused Nant-y-Gro dam in Wales in July. A subsequent test suggested that a charge of 7,500 lb (3,400 kg) exploded 30 ft (9.1 m) under water would breach a full-size dam; crucially this weight would be within the carrying capacity of an Avro Lancaster. The first air drop trials were at Chesil Beach in December 1942; these used a spinning 4 ft 6 in sphere dropped from a modified Vickers Wellington, serial BJ895/G; the same aircraft was used until April 1943 when the first modified Lancasters became available. The tests continued at Chesil Beach and Reculver, often unsuccessfully, using revised designs of the mine and variations of speed and height.
Avro Chief Designer Roy Chadwick adapted the Lancaster to carry the mine. To reduce weight, much of the internal armour was removed, as was the mid-upper (dorsal) gun turret. The dimensions of the mine and its unusual shape meant that the bomb-bay doors had to be removed and the mine hung partly below the fuselage. It was mounted on two crutches and before dropping it was spun by an auxiliary motor. Chadwick also worked out the design and installation of controls and gear for the carriage and release of the mine in conjunction with Barnes Wallis. The Avro Lancaster B Mk IIIs so modified were known as Lancaster B Mark III Special (Type 464 Provisioning).
In February 1943, Air Vice-Marshal Francis Linnell at the Ministry of Aircraft Production thought the work was diverting Wallis from the development of the Vickers Windsor bomber (which did not become operational). Pressure from Linnell via the chairman of Vickers, Sir Charles Worthington Craven, caused Wallis to offer to resign.[12] Sir Arthur Harris, head of Bomber Command, after a briefing by Linnell also opposed the allocation of his bombers; Harris was about to start the strategic bombing campaign against Germany and Lancasters were just entering service. Wallis had written to an influential intelligence officer, Group Captain Frederick Winterbotham, who ensured that the Chief of the Air Staff, Air Chief Marshal Charles Portal, heard of the project. Portal saw the film of the Chesil Beach trials and was convinced.[13] On 26 February 1943, Portal over-ruled Harris and ordered that thirty Lancasters were to be allocated to the mission and the target date was set for May, when water levels would be at their highest and breaches in the dams would cause the most damage.[14] With eight weeks to go, the larger Upkeep mine that was needed for the mission and the modifications to the Lancasters had yet to be designed.
The operation was given to No. 5 Group RAF, which formed a new squadron to undertake the dams mission. It was initially called Squadron X, as the speed of its formation outstripped the RAF process for naming squadrons. Led by 24-year-old Wing Commander Guy Gibson, a veteran of more than 170 bombing and night-fighter missions, twenty-one bomber crews were selected from 5 Group squadrons. The crews included RAF personnel of several nationalities, members of the Royal Australian Air Force (RAAF), Royal Canadian Air Force (RCAF) and Royal New Zealand Air Force (RNZAF). The squadron was based at RAF Scampton, about 5 mi (8 km) north of Lincoln.
The targets selected were the Möhne Dam and the Sorpe Dam, upstream from the Ruhr industrial area, with the Eder Dam on the Eder River, which feeds into the Weser, as a secondary target. The loss of hydroelectric power was important but the loss of water to industry, cities and canals would have greater effect and there was potential for devastating flooding if the dams broke.
Bombing from an altitude of 60 ft (18 m), at an air speed of 240 mph (390 km/h) and at set distance from the target called for expert crews. Intensive night-time and low-altitude training began. There were also technical problems to solve, the first one being to determine when the aircraft was at optimum distance from its target. The Möhne and Eder Dams had towers at each end. A special targeting device with two prongs, making the same angle as the two towers at the correct distance from the dam, showed when to release the bomb. (The BBC documentary Dambusters Declassified (2010) stated that the pronged device was not used, owing to problems related to vibration and that other methods were employed, including a length of string tied in a loop and pulled back centrally to a fixed point in the manner of a catapult.)
The second problem was determining the aircraft's altitude, as barometric altimeters lacked accuracy. Two spotlights were mounted, one under the aircraft's nose and the other under the fuselage, so that at the correct height their light beams would converge on the surface of the water. The crews practised at the Eyebrook Reservoir, near Uppingham, Rutland; Abberton Reservoir near Colchester; Derwent Reservoir in the Derbyshire Peak District; and Fleet Lagoon on Chesil Beach. Wallis's bomb was first tested at the Elan Valley Reservoirs. The squadron took delivery of the bombs on 13 May, after the final tests on 29 April. At 18:00 on 15 May, at a meeting in Whitworth's house, Gibson and Wallis briefed the squadron's two flight commanders, Squadron Leader Henry Maudslay and Sqn Ldr H. M. "Dinghy" Young, Gibson's deputy for the Möhne attack, Flt Lt John V. Hopgood and the squadron bombing leader, Flight Lieutenant Bob Hay. The rest of the crews were told at a series of briefings the following day, which began with a briefing of pilots, navigators and bomb-aimers at about midday.
Formation No. 1 was composed of nine aircraft in three groups (listed by pilot): Gibson, Hopgood and Flt Lt H. B. "Micky" Martin (an Australian serving in the RAF); Young, Flt Lt David Maltby and Flt Lt Dave Shannon (RAAF); and Maudslay, Flt Lt Bill Astell and Pilot Officer Les Knight (RAAF). Its mission was to attack the Möhne; any aircraft with bombs remaining would then attack the Eder.
Formation No. 2, numbering five aircraft, piloted by Flt Lt Joe McCarthy (an American serving in the RCAF), Pilot Officer Vernon Byers (RCAF),[15] Flt Lt Norman Barlow (RAAF), Pilot Officer Geoff Rice[16] and Flt Lt Les Munro (RNZAF), was to attack the Sorpe.
Formation No. 3 was a mobile reserve consisting of aircraft piloted by Flight Sergeant Cyril Anderson, Flt Sergeant Bill Townsend, Flt Sergeant Ken Brown (RCAF), Pilot Officer Warner Ottley and Pilot Officer Lewis Burpee (RCAF), taking off two hours later on 17 May, either to bomb the main dams or to attack three smaller secondary target dams: the Lister, the Ennepe and the Diemel.
Two crews were unable to make the mission owing to illness.
source: Wikipedia
6 Group Bomber Command