Heavy bomber version of the bouncing bomb, was used to destroy the Mohne and Eder dams by Lancasters from the specially recruited and trained 617 Squadron, often known as the Dambusters, under Wing Commander Guy Gibson. In March and April 1945, as the war in Europe was ending, Lancasters dropped Grand Slams and Tallboys on U-boat pens and railway viaducts across north Germany. At Bielefeld more than of railway viaduct was destroyed by Grand Slams creating an earthquake effect, which shook the foundations. The Boeing B-29 Superfortress was a development of the Fortress, but a larger design with four Wright R-3350 Duplex-Cyclone
Wing leader given responsibility for coordinating the operations of several squadrons—originally three, later as many as five—in combat. Previously, such formations were led by the most senior or experienced commander of the squadrons involved. The "Big Wing" had been conceived as a defensive measure against German air raids during the Battle of Britain in 1940, when Squadron Leader Douglas Bader led the prototypical Duxford Wing in combat, though the distinct "wing leader" position had not yet been devised. In December 1940, RAF Fighter Command began preparing for offensive fighter sweeps over France, using massed formations under the tactical command of wing leaders,