10. The RAF’s Enterprising Aerial Commandos
Once Barnes Wallis’ rapidly rotating drum bombs skipped across the water, over the anti-torpedo nets, and struck the dam, the drum’s counter-rotation would ensure that it hugged the dam’s wall while sinking. Once the bomb reached the proper depth, hydraulic pistols would set it off, and basic physics would take care of the rest. Wallis’ science was good and his theory was sound. Next was getting pilots and aircrews with enough skill and courage to conduct the night time raid.

24-year-old Wing Commander Guy Gibson was personally selected by RAF Bomber Command’s chief, Arthur Harris, to form and lead 617 Squadron for that and similar missions. It was essentially a unit of elite aerial commandos. Gibson’s enterprising 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. To determine the correct height, an ingeniously simple technique was adopted: two spotlights were placed on a bomber’s front and rear, and angled so their lights would meet at the water’s surface at a height of 60 feet.