On March 29, 1945, the railway viaduct at Bielefeld, Germany, was attacked by RAF Lancaster's of 617 Squadron, (The Dambusters). The bombers were specially modified to carry the 'Grand Slam' the monster 22,000lb (9,979kg) bomb designed by Barnes Wallace. At almost 10 tons, the Lancaster could only carry one bomb at a time. Piloted by Squadron Leader C. Calder, his Lancaster, one of the 33 converted, dropped the bomb about thirty metres from the viaduct, the resulting explosion caused powerful shock waves to radiate outwards destroying two arches each 1,100 feet in length. The bomb was the largest ever used in war, it could penetrate seven meters (23 feet) of reinforced concrete as it did on the U-boat pens near Bremen. The Grand Slam measured 7.7 meters in length and contained 4,144 kg of explosive. A total of 41 of these bombs were dropped during the war. In all, 7,374 Lancaster bombers were built during the war. (The last RAF crews to loose their lives in the war were the crews of two Halifax bombers which collided in mid-air during a raid on Kiel on May 2, 1945. All thirteen crew members were killed)
Source: http://members.iinet.net.au/~gduncan/1944.html
Source: http://members.iinet.net.au/~gduncan/1944.html