Supergun
A supergun is an extraordinarily large cannon with an extremely high muzzle velocity and large bore. They were originally used to bombard an enemy from extremely long range, but have since been used in experiments in launching satellites into orbit.
The World War I and World War II German military were especially interested in the development of these superweapons until rocketry supplanted the usefulness of the large railway guns. The largest of the railway guns deployed in World War I was the Paris Gun, which was used to bombard Paris from a distance of over 70 miles (113 km). World War II saw the V-3 "London Gun" weapon, intended to bombard London from a site in the Pas de Calais, about 95 miles (153 km) away, although it was destroyed by aerial attack before it could go into service. There was also the 80cm Schwerer Gustav, which fired a 7 ton shell to a range of 37 km, and was used successfully to demolish several heavy fortifications, most notably those at Sevastopol. It was the largest artillery piece (by caliber) ever used in combat.
Gerald Bull later became interested in the possibility of using superguns in place of rockets to insert payloads into orbit. He started Project HARP to investigate this concept. HARP was later cancelled, but Bull did not lose interest in the concept. Some years later, Bull interested Saddam Hussein in funding Project Babylon. The objective of this project is not certain, but it is thought to have been intended to develop a gun capable of firing an object into orbit, from where it could then drop onto any place on the Earth.
Gerald Bull was assassinated, allegedly by Israeli Mossad agents, terminating development, and the parts were confiscated by British customs.
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Supergun