RAF Launches Operation Chastise, May 16, 1943

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Today in 1943, the British Royal Air Force launched Operation Chastise, a coordinated attack on several dams in the Ruhr area of Germany. The mission is considered one of the most daring bombing raids of the Second World War.

The Dam Busters raid, as it was later called, began with a design for a bomb. That bomb was the design of Barnes Wallis, a highly successful aircraft designer. He envisioned a 20,000 pound bomb dropped from 40,000 feet. However, it quickly became apparent that a bomb necessary to breach a dam in this way would be too heavy for any bomber then in service to carry. Instead, Wallis designed a bomb that would skip across the water and explode directly against the face of the dam. Unfortunately, the Germans had thought of this and protected all of their dams with heavy netting that would stop such a weapon before it got near the dam.

Finally, Wallis designed a drum-shaped bomb that would be spun rapidly backwards when it was dropped. It would bounce across the water to the dam wall and, once there, the remaining spin would carry the bomb to the base of the dam where it would explode via a hydrostatic fuse. The design was approved in February, 1943 and the date of the mission was set for May, when the spring rains and winter run-off would raise the water levels to their highest point for the year.

The RAF created a new squadron for the mission and initially called it Squadron X, although it later became the No. 617 Squadron. The squadron’s leader was Wing Commander Guy Gibson, an experienced pilot with over 170 missions under his belt. The squadron soon consisted of 21 crews who were assigned trusty Lancaster bombers. However, these Lancasters were modified just for this mission: much of their armor was removed and the bomb bay doors were removed so as to allow each aircraft to carry one bomb mounted halfway out of the fuselage and spun up to 500 RPM by a small motor. For the bombs to work as designed, they had to be dropped a precise distance from the dams and no more than 60 feet above the water.

The primary targets of the raid were the Mohne, Eder and Sorpe dams. Three smaller dams at Schwelm, Ennepe and Diemel served as backup targets. The aircraft were broken down into three formations: one group of nine planes, one of five and one of four. The Lancasters flew to their targets at late on the 16th at altitudes below 120 feet. The first formation bombed the Mohne dam and breached it even though it was heavily defended. Wing Commander Gibson bombed first and then flew his empty plane on another run so as to draw flak away from the other aircraft.

The Eder dam was not defended, but the surrounding hills made the bombing run so difficult that the first aircraft had to try six times before dropping it’s payload on the target. It, too, was breached after two direct hits.

The Sorpe dam was different than the other two in that it was earthen instead of concrete. It survived two direct hits, after which the remaining aircraft were ordered to Ennepe. That dam survived as well.

The lakes behind the Mohne and Eder dams caused flood water to surge for 50 miles downstream, destroying everything in its path. Nearly 1,300 people were killed in the flooding; 794 of the dead were Ukrainian POWs. However, instead of having a crippling effect on German industry, the bombing merely caused a hiccup; the dams were repaired by October, 1943.

Of the 133 airmen who took part in the raid 53 were killed and 3 were captured and held for the rest of the war as POWs. Eight aircraft were lost and two were forced to turn back before reaching their targets. 33 of the surviving aircrew were decorated, with Wing Commander Gibson being awarded the Victoria Cross. He was killed the next year while on a mission. No. 617 Squadron stayed together and spent the rest of the war doing special missions like the dam busters raid. It is still active today.