617Dambusters

They were used throughout the 1930s, 40s and even the 1950s to perform all sorts of difficult computing tasks — to create artillery firing tables, for example, and to calculate soil erosion. However, the only original, complete Differential Analyser left in the world happens to be the one that helped Barnes Wallis design his famous bouncing bombs. They were the ones used in the Dam Busters attack on German hydro electric dams, in the Ruhr Valley, during World War II.