Operation Chastise – Training and Raid
Barnes Wallis’ science was good and his theory was sound. Next was getting pilots and aircrews with enough skill and courage to conduct the nighttime raid. 24-year-old Wing Commander Guy Gibson was personally selected by RAF Bomber Command’s chief, Arthur Harris, to form and lead a special squadron for that and similar missions – essentially a unit of specially trained elite aerial commandos.
Gibson’s aircrews trained in modified Lancaster heavy bombers, fitted with a motor in the bomb bay to spin the explosive drum. The drum had to be released at a height of 60 feet to properly skip on water, and to determine the correct height, an ingeniously simple technique was adopted: two spotlights were placed on the bomber’s front and rear and angled so their lights would meet at the water’s surface when the bomber was 60 feet above the ground.
Correct distance would be determined by lining up two sticks on the windshield with two towers to the sides of dam. As the bomber flew in, the sticks would visually be to the outside of the dam towers, sandwiching them. As the bomber drew nearer, the angle between bomber and towers would grow wider, and as seen from the windshield, the towers would “move” closer to the sticks until, at the correct distance, sticks and towers lined up.
19 Lancaster bombers of 617 Squadron, divided into three formations with separate assignments, flew out on the night of May 16, 1943, along routes chosen to avoid known flak concentrations. Losses began soon as the bombers reached the European coast, and two bombers had to turn back after one flew too low and struck water, losing its explosives, while another had its radio damaged by antiaircraft fire. Soon thereafter, a third bomber was shot down, a fourth went down after striking electric pylons, and a fifth crashed after flying into power lines.
At the Mohne dam, Guy Gibson made his attack run, then flew his bomber across the dam to draw antiaircraft fire while other bombers made their approaches. One bomber was lost and another damaged, but the dam was finally breached after the fifth bombing run. Gibson then led the Lancasters that still had bombs to the Edersee dam, which was undefended but the angle of approach was difficult, and made even more hazardous by fog. After repeated aborted runs, it was finally breached. The attack on the Sorpe dam did not succeed.
The breached dams resulted in a flood that killed about 1700 civilians, of whom 1000 were forced laborers. The greatest impact was the loss of hydroelectric power to factories and residences in the Ruhr for two weeks, as two power stations were destroyed and seven more damaged. Coal production also dropped, declining 400,000 tons that month. The damage was not permanent, however, and within two months the Ruhr was back to normal. The raid nonetheless gave a boost to British morale as an impressive feat of derring-do, Guy Gibson was awarded a Victoria Cross, and the 617 Squadron, known thereafter as the “Dam Busters”, went on to fly further successful special raids.