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 commander (rank) triangular command pennants used in the RAF. Two thin red lines differentiate this one from the other. During 1941-45 RAF Fighter Command's wing leaders (of wing commander rank) were also allowed to use their own initials as aircraft identification letters on their personal aircraft, e.g., Wing Commander Roland Beamont's personal Hawker Tempest, "JN751", was coded "R-B", Wing Commander John Robert Baldwin's personal Hawker Typhoon was coded "J-B". The rank of wing commander is also used in a number of the air forces in the Commonwealth, including the Bangladesh Air Force, Ghana Air Force, Nigerian Air Force, Indian Air Force, Pakistan