Operation Chastise

Operation Chastise was the official name for the attacks on German dams on May 17, 1943 in World War II using a specially developed "bouncing bomb". The attack was carried out by Royal Air Force No. 617 Squadron, subsequently known as the Dam Busters.

Development of the plan

The mission developed out of a bomb designed by Barnes Wallis and developed into a working device by a team at Vickers. Wallis was an aircraft designer and had the successful Wellesley and Wellington to his credit. While working on the Warwick, he also began work on bomb design with dams specifically in mind.

His initial idea was for a 10-ton bomb to be dropped from 40,000 feet (12,200 m). However, research showed that a bomb sufficient to breach dam without a direct hit would be too heavy for any available bomber to carry. A much smaller charge would suffice if it could be exploded directly against the dam wall below the surface of the water. The major German dams were protected by heavy torpedo netting to prevent such an attack, and Wallis's breakthrough was to overcome this. A drum-shaped bomb, spinning rapidly backwards and dropped from a sufficiently low altitude at the right speed, would skip for the required distance over the surface of the water in a series of bounces before reaching the dam wall and using its residual spin to run down the wet side to the dam's base. An accurate drop could bypass the dam protection and let the bomb be detonated against the dam with a hydrostatic fuse. After testing, and many meetings, the idea was adopted on February 26, 1943. The bomb was codenamed 'Upkeep'. The dams were to be bombed in May of that year, when water levels would be highest.

The operation was given to 5 Group which formed a new squadron to undertake the mission. Initially called Squadron 'X', it was led by Wing Commander Guy Gibson, a veteran of over 170 missions. A further 21 crews were chosen from 5 Group to join the new squadron based at RAF Scampton, 5 miles north of Lincoln.

The targets were the three key dams in the Ruhr area, the Möhne and the Sorpe on the Ruhr River and the Eder Dam on the Eder River. The loss of hydroelectric power was important but the loss of water to industry, cities and canals would have greater effect.

The aircraft were adapted Avro Lancaster Mk IIIs, dubbed Type 464 (Provisioning). To reduce weight, much of the armour was removed, as was the mid-upper turret. The substantial bomb and its unusual shape meant that the bomb doors were removed and the bomb itself hung, in part, below the body of the aircraft. It was mounted in two crutches and before dropping, it was spun up to speed by an auxiliary motor.

Bombing from 60 feet (18 m) at 240 mph (390 km/h), at a very precise distance from the target, required expert crews, intensive night and low-altitude flying training, and the solutions to two technical problems. The first was to know when the airplane was the correct distance from the target. The two key dams at Moehne and Eder had a tower at each end. A special aiming device (a 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 second problem was to measure the airplane's altitude (the usual barometric altimeters were insufficiently accurate). Two spotlights were mounted under the nose and under the fuselage such that their beams would intersect 60 feet (18 m) from the underside of the plane. At the correct height, the two spots of light would merge into one on the surface of the water. The crews practised over the Eyebrook reservoir in Leicestershire (built in 1940 to supply Corby steelworks), and the Derwent Reservoir, Derbyshire. See also: British reservoirs.

The bombs were delivered to the squadron on 13 May, after the final tests on 29 April. With promising weather reports the pilots, navigators and bomb aimers were informed of the targets on 15 May, the rest of the crews on the following day.

The attacks

Organisation

The Lancasters were organised into three groups. Formation 1 was to attack the Moehne and after that, aircraft still with bombs would attack the Eder. Formation 2 was to attack the Sorpe. The third group was a mobile reserve, it would take off two hours later and bomb as directed, either attacking the main dams or bombing smaller dams at Schwelm, Ennepe and Diemel.

The operations room for the mission was at 5 Group headquarters in Grantham. The codes, transmitted in morse, for the mission were agreed on as Goner for bomb dropped, Nigger for the Moehne breached, Dinghy for the Eder breached and ?? for the Sorpe breached. The Nigger code was after Gibson's black dog that had been run-over and killed on the morning of the 17th.

The Outbound Flights

The outbound flights were flown at treetop level (between 75 and 120 feet) to avoid detection by the German air defence radar. The aircraft flew two routes, carefully skirting known flak hot spots.

Formation 1 entered continental Europe between Walcheren and Schouwen, crossed the Netherlands, skirting the airbases at Eindhoven and Gilze-Rijen, curved round the Ruhr defences and turned north to avoid Hamm before turning to head south to the Moehne. Formation 2 flew further northwards, cutting over Vlieland and crossing the Zuider Zee before joining the first route near Wesel and then flying south beyond the Moehne to the Sorpe.

Formation 1 was of nine aircraft in three groups — Gibson, Hopgood, Martin; Young, Astell, Maltby; and Maudslay, Knight, Shannon. Formation 2 was of five aircraft, those of McCarthy, Byers, Barlow, Rice and Munro. Formation 3 consisted of the aircraft of Townsend, Brown, Ottley and Burpee. Two crews were unable to make the mission because of illness.

The first aircraft, those of Formation 2 and heading for the longer northern route, took off at 21h10. McCarthy's aircraft had a hydraulics fault and he took off in a reserve craft twenty minutes late. Formation 1 took off from 21h25.

The first casualties were taken soon after the craft reached the Dutch coast. Formation 2 did not fare well: Munro's aircraft lost his radio to flak and turned back over the Zuider Zee while Rice flew too low and lost his bomb in the water but recovered the aircraft to return to base. The aircraft of both Barlow and Byers crossed over the coast around Harderwijk and were shot down shortly thereafter. Only the tardy aircraft of McCarthy survived across the Netherlands. Formation 1 lost only Astell, somewhere over Rosendaal.

The attack on the Mohne dam

Formation 1 arrived over Moehne Lake and Gibson's aircraft (G for George) bombed first. Hopgood (M for Mother) attacked second. Hopgood's aircraft was hit by flak as it made its low-level run and was then caught in the blast of its own bomb and destroyed. Martin (P for Peter) bombed third; his aircraft was hit but made a successful attack. Then Young (A for Apple) made a successful run and after him Maltby (J for Johnny) and then, finally, the dam was breached. Gibson then led Young, Shannon, Maudslay and Knight to the Eder.

The attack on the Edder dam

The Eder valley was heavily fogged but not defended. The tricky topography of the surrounding hills made the approach difficult and the first aircraft, Shannon's, made six runs before taking a break. Maudslay (Z for Zebra) then attempted a run but the bomb struck the top of the dam and the aircraft was caught in the blast. Shannon made another run and successfully dropped his bomb and the final bomb of the formation, from Knight's aircraft, breached the dam.

The attacks on the Sorpe and Ennepe dams

McCarthy (T for Tom) reached the Sorpe alone. It was the least likely to be breached — a vast earth dam rather than the two concrete structures successfully attacked. Despite the mist and ill-placed hills, McCarthy's aircraft successfully dropped its bomb but did not breach the dam. Three of the reserve aircraft were directed to the Sorpe. Burpee (S for Sugar) never reached the dam. Brown (F for Freddy) reached the dam and in increasingly dense mist finally dropped his bomb without breaking the dam. Anderson (Y for Yorker) arrived last and the mist was too dense for him to even attempt the run. The remaining two aircraft were sent to subsidiary targets, Ottley (C for Charlie) was shot down en route while Townsend (O for Orange) successfully dropped his bomb on the Ennepe.

The return flights

On the way back, flying again at treetop level, one further aircraft was lost, that of Young which was hit by flak and crashed into the sea just off the coast of Holland.

Complete list of the aircraft involved

After the Raid

In all, 53 of the 133 aircrew were killed and three bailed out to be made POWs. Of the surviving aircrew thirty-three were decorated at Buckingham Palace on 22 June, with Gibson awarded the Victoria Cross. There were five DSOs, ten DFCs and four bars, twelve DFMs and two CGMs.

After a public relations tour of America, Gibson returned to operations and was killed on a mission in 1944.

Following the dams raid, 617 squadron was kept together as a specialist unit. The squadron badge ("on a roundel, a wall in fesse, fracted by three flashes of lightening in pile and issuant from the breach, water proper") was chosen and a motto "Après moi le déluge". The squadron went on to drop Wallis' massive Tallboy bomb and Grand Slam bomb, using an advanced bomb sight which enabled the bombing of small targets with far greater accuracy than was routinely obtained with conventional bomb aiming techniques. The squadron is still active today.

Effect on the war

The tactical view

The Moehne and Eder lakes poured around 330 million tons of water into the western Ruhr region. Mines were flooded and houses, factories, roads, railways and bridges destroyed as the flood waters spread for around 50 miles (80 km) from the source. Estimates show that before 15 May 1943 water production on the Ruhr was 1 million tonnes, which dropped to a quarter of that level after the raid. In terms of deaths: 1,294 people were killed, 749 of them Ukrainian POWs from a camp just below the Eder Dam. After the operation Barnes Wallis wrote, "I feel a blow has been struck at Germany from which she cannot recover for several years".

However, on closer inspection, Operation Chastise did not have the military effect that was at the time believed. By 27 June, full water output was restored, thanks to an emergency pumping scheme inaugurated only the previous year, and the electricity grid was again producing power at full capacity. The raid proved to be costly in lives (more than half the lives lost belonging to allied POWs), but in fact no more than a minor inconvenience to the Ruhr's industrial output. However, the pictures of the broken dams proved to be an immense morale boost to the Allies, especially to the British, still suffering under German bombing.

The diplomatic view

An important reason for planning the raid was to persuade Stalin that Britain was capable of being an effective ally and that as a consequence, the Soviet Union should continue to resist the German invasion of its territory.

This was the middle period of the war when the Japanese had relatively recently brought the United States into it on Britain's side (see Attack on Pearl Harbor). Germany had a little earlier done the same with the Soviet Union (see Operation Barbarossa). However, the Soviet Union was in a very serious position, although by the time the preparations for the raid were complete the USSR had found the capacity to begin its counter-offensive on the Don and Volga. See Battle of Stalingrad. The Dams Raid enabled Churchill, in negotiations with the leaders of these new allies, to point to an effective strike against the hitherto apparently invincible German state so that he was taken more seriously as an ally than might otherwise have been the case. This was relevant vis-à-vis Stalin but also in the USA. Although Churchill had the sympathetic ear of Roosevelt, many of the US military staff were less persuaded of the value of British experience and capabilities. (See Churchill, W.S. (1951).)

The strategic view

The Dams Raid was, like many of the air raids, undertaken with an ongoing view to the need to keep drawing German defensive effort back into Germany and away from actual and potential theatres of ground war, a policy which culminated in the Berlin raids of the winter of 1943–44. In May 1943 this meant keeping the Luftwaffe and anti-aircraft defence forces' effort away from the Soviet Union; in early 1944, it meant clearing the way for the aerial side of the forthcoming Operation Overlord.

Notes

A 1954 movie, The Dam Busters was made about the raids and was very popular.

Bibliography

• The Dambusters Raid, John Sweetman (Cassell, 1999). Good "warts and all" account.
• The Dam Busters, Paul Brickhill (1952). 'Novelised' style. Covers entire wartime story of 617 Squadron.
• Enemy Coast Ahead, Guy Gibson (1955). Gibson's own account, written before his death on operations in 1944.
• Churchill, W.S. The Second World War (1951) Vol IV Chapetr XXV. [Concerning US military attitudes to involvement in Europe.]

External links

• Site with details of the raids, full crew listing, links to present day 617 Sqn and much more (http://www.dambusters.org.uk/)
• Online Dambusters exhibition (http://www.nationalarchives.gov.uk/dambusters/) at the UK National Archives
• Secrets of the Dead: Bombing Nazi Dams (http://www.pbs.org/wnet/secrets/case_nazidams/index.html) and their link page (http://www.pbs.org/wnet/secrets/case_nazidams/resources.html)
• BBC Online - Myths and Legends - Home of the Dambusters (http://www.bbc.co.uk/legacies/myths_legends/england/lincolnshire/article_1.shtml)
• 50th Anniversary BBC News. (http://news.bbc.co.uk/1/hi/uk/3036315.stm)
• Imdb Archive Information (http://uk.imdb.com/title/tt0046889)no:Operasjon Chastise

pt:Operação Chastise