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
Thousand-bomber raids Thousand-bomber raids The term "thousand-bomber raid" was used to describe three night bombing raids by the Royal Air Force against German cities in summer 1942 during World War II. The term was a propaganda device, whereby Arthur Harris included the relatively few modern four-engined "heavy" bombers that were currently operational, but mostly 1930s-era twin-engine "medium" bombers and many otherwise unsuitable small bombers and trainee aircrews in the raids to accumulate a force of 1,000 bombers as a demonstration of the RAF's growing power. Later RAF raids concentrated on effectiveness rather than sheer number, with raids of 400-700 four-engined bombers occurring,