Plot

Drama based on the attempt by the RAF to destroy six dams in Germany during World War II.

The British are desperate to shorten the length of World War II and propose a daring raid to smash Germany's industrial heart. At first, the objective looks impossible until a British scientist invents an ingenious weapon capable of destroying the planned target.—Dave Jenkins <david.jenkins@smallworld.co.uk>

1942. British inventor Dr. B.N. Wallis, C.B.E., F.R.S. (Sir Michael Redgrave) is struggling with the task of finding a way of destroying the dams in the Ruhr valley. Breaching these dams will significantly reduce Germany's military production, especially steel. He hits upon a method, but struggles to find any government department to endorse it. Will his idea get off the ground?—grantss

In early 1942, aeronautical engineer Barnes Wallis (Michael Redgrave) (assistant chief designer, Aviation Section, Vickers-Armstrong Ltd) is struggling to develop a means of attacking Germany's dams in the hope of crippling German heavy industry. It takes Germans 100 tons of water to produce 1 ton of steel. and the entire industrial area of Ruhr depends on 3 dams for its water supply. These 3 dams alone hold 400 million tons of water. Barnes lives with his wife Mrs Molly Wallis (Ursula Jeans) and kids. Barnes is working late nights trying to develop his solution and this worries Molly.

Barnes initial plan was to drop a 10-ton bomb into the dam from 40,000 ft, but there was no plane large enough to carry such a bomb. The trick is to get the bomb right next to the dam wall, as any distance between the bomb and dam creates a cushion of water that absorbs the shock wave of the bomb completely.

Working for the Ministry of Aircraft Production, as well as his own job at Vickers, he works feverishly (over many months) to make practical his theory of a bouncing bomb which would skip over the water to avoid protective torpedo nets. When it hit the dam, backspin would make it sink whilst retaining contact with the wall, making the explosion far more destructive. Wallis calculates that the aircraft will have to fly extremely low (150 feet (46 m) & 250 mph) to enable the bombs to skip over the water correctly, but when he takes his conclusions to the Ministry, he is told that lack of production capacity (Factory space, raw materials as well as skilled labor to produce bombs of a completely new design) means they cannot go ahead with his proposals. Barnes is able to get a few dummy bombs made and tests them with Captain Joseph "Mutt" Summers (Patrick Barr), Chief Test Pilot, Vickers-Armstrong Ltd. They prove the concept, but the ministry says production of full-scale bombs is impossible.

Angry and frustrated, Wallis secures an interview with Sir Arthur "Bomber" Harris (Basil Sydney), Air Chief Marshal GOC-in-C, the head of RAF Bomber Command, who at first is reluctant to take the idea seriously. Eventually, however, he is convinced and takes the idea to the Prime Minister, who authorizes the project. The attack has to happen in May, when the water level is the highest in the dams. That leaves only 2 months to prepare the bombs and train a squadron.

Bomber Command led by Air Vice-Marshal Ralph Cochrane (Ernest Clark), AOC, No. 5 Group RAF forms a special squadron of Lancaster bombers, 617 Squadron, to be commanded by Wing Commander Guy Gibson (Richard Todd) (CO of 617 Squadron and pilot of "George"), and tasked to fly the mission. He recruits experienced crews, especially those with low-altitude flight experience. The squad is hosted by Group Captain John Whitworth (Derek Farr), station commander, RAF Scampton.

Flight Lieutenant Richard Trevor-Roper (Brewster Mason), rear gunner of "George", Flight Lieutenant Robert Hutchison (Anthony Doonan), wireless operator of "George", Flying Officer Frederick Spafford (Nigel Stock), bomb aiming specialist of "George", Flight Lieutenant Torger Taerum (Brian Nissen), navigator of "George", Flight Sergeant John Pulford (Robert Shaw), flight engineer of "George", Pilot Officer Andrew Deering (Peter Assinder), front gunner of "George". Squadron Leader Melvin "Dinghy" Young (Richard Leech), pilot of "Apple". Squadron Leader Henry Maudslay (Richard Thorp), pilot of "Zebra". Flying Officer Les Knight (Denys Graham), pilot of "Nancy". Flight Lieutenant John Hopgood (John Fraser), pilot of "Mother". Flight Lieutenant Bill Astell (David Morrell), pilot of "Baker". Flight Lieutenant Dave Shannon (Ronald Wilson), pilot of "Leather". Flight Lieutenant David Maltby (George Baker), pilot of "Johnny". Flight Lieutenant H. B. "Micky" Martin (Bill Kerr), pilot of "Popsie", Flight Lieutenant Bob Hay (Basil Appleby), bomb aiming specialist of "Popsie" & Flight Lieutenant Jack Leggo (Tim Turner), navigator of "Popsie"

Gibson gets 10 bombers to start training his crews. They practice low level flying and photograph all the big lakes of Britain in the process. Maintaining 150 ft is impossible as at that height the altimeters of the planes don't work. Over still water at night, it is near impossible to get a good sense of the height. Gibson has the idea to use to converging beams of light, that converge at precisely 150 ft to get over their height issue.

While they train for the mission, Wallis continues his development of the bomb but has problems, such as the bomb breaking apart upon hitting the water. This requires the drop altitude to be reduced to 60 feet (18 m). With only a few weeks to go, he succeeds in fixing the problems and the mission can go ahead. The squad has flown for 2000 hours and dropped 2000 practice bombs to get their aims and timing right.

The bombers attack the dams. Gibson makes 3 teams. 1st team of 9 planes to attacks Mohne and Eder. 2nd team of 5 planes to attack Sorpe. 3rd team of 5 planes as mobile replacements. It is a full moon night, so normal ops are out, and they are the only ones flying. The crews have their meals and prepare for the mission just like any other normal day.

Eight Lancasters and their crews are lost, but two dams are breached, and the overall mission succeeds. The first attack on Mohne by 3 planes is unsuccessful, and 1 plane is shot down. the 5th bomb on Mohne produces a breach and the 1st team moves on to Eder. There are only 4 bombs left for Eder. But the dam has a difficult approach, and a mountain right up front. The planes can't get the height right and one plane flies into the mountain. The last bomb on Eder breaks it.

Wallis later encounters Gibson, clearly affected by the loss of the crewmen, but Gibson stresses the squadron knew what they were facing but they went in regardless of the odds. Before they part Wallis asks if Gibson will finally get some sleep. Gibson says he cannot; he has to write letters to the dead airmen's next of kin.