Large-calibre artillery

In the context of late medieval siege warfare the term superguns applies to stone-firing bombards with a ball diameter of more than 50 cm (20 in).

These, however, exerted larger pressure on the existing cannon and could make it burst, causing the death of the irreplaceable gunner with his crew (and even kings).

For the cost of a single supergun, two or three large bombards with a reasonably smaller caliber (in German Hauptbüchse) could be produced whose firepower was enough to shatter any medieval wall, in particular when it was concentrated in a battery.

Due to their less bulky dimensions and higher rate of fire, these artillery pieces could be more flexibly deployed and caused more destruction in any given length of time.

[7] Thus, as early as the second half of the 15th century, further development in siege technology concentrated on the Hauptbüchse,[8] and bombards largely disappeared from the leading artillery arsenal of the dukes of Burgundy.

[9] At about the same time super-sized bombards were phased out in Western Europe, the technology was transmitted to the Ottoman army by one Orban, a Hungarian gunfounder, on the occasion of the Siege of Constantinople in 1453.

In the 1860s, the industrialist Sir William Armstrong, who had already built one of the first breech-loading rifled artillery pieces, constructed a 600-pounder 'monster gun' of then extraordinary size at the Elswick Ordnance Company in Newcastle.

[13][page needed] By the 1880s he had built guns of over 40 feet (12 m) in length that could fire 1,800 pound (810 kg) shells and punch through an incredible 30 inches (76 cm) of iron at a range of 8 mi (13 km).

[14] Prior to World War I, the German military was especially interested in the development of superweapons due to the need for the Schlieffen plan to march past a line of Belgian fortifications constructed specifically to stop such an invasion route.

Development might have continued but for the ever-increasing Allied air power, which limited Hitler's options in terms of re-opening bombing attacks on London.

He lobbied for the start of Project HARP to investigate this concept in the 1960s, using paired ex-US Navy 16"/50 caliber Mark 7 gun barrels welded end-to-end.

[citation needed] Gerald Bull was assassinated in March 1990, terminating development, and the parts were confiscated by British customs after the Gulf War.

It has been suggested that the US Navy had developed a supergun (actually a prototype railgun, known as the Electro-Magnetic Laboratory Rail Gun), capable of shooting shells at 5,600 mph (9,012 km/h) or Mach 7 (seven times the speed of sound).