Supergun A supergun is an extraordinarily large artillery piece . This size may be due to a large bore , barrel length , or a combination of the two . While early examples tended to have a fairly short range , more recent examples have sometimes had an extremely high muzzle velocity , resulting in a very long range . Depending on the design , they may be used to destroy heavy fortifications or bombard an enemy from extremely long range . Late Middle Ages . In the context of late medieval siege warfare the term superguns is sometimes applied to stone - firing bombard s with a ball diameter of more than 50 cm . These superguns were either manufactured by forging together longitudinal iron bars , held in place by iron rings , or cast in bronze with techniques generally similar to bellfounding . Known examples include the Pumhart von Steyr , Dulle Griet and Mons Meg ( all iron ) as well as the cast - bronze Faule Mette , Faule Grete and Dardanelles Gun . At the beginning of the development of superguns was the desire to increase the effect of the projectiles . To this end , master gunners first simply used larger powder loads . 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 ) . In addition , it was observed that , due to their higher velocity , stone balls were shattered by the impact on the walls rather than smashing them . Thus , the mass of the cannon balls and , consequently , of the ordnance too continually increased , finally culminating in giant cannon like the Pumhart von Steyr which fired a 690 kg ball . Apart from the anticipated improvement in penetrating power , other factors such as prestige and a potential deterrent effect also played an important role . For all their manufacturing quality the superguns were only moderately successful . Their military effectiveness turned out to be out of all proportion to their overwhelming logistical demands and financial costs . 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 . Furthermore , the transition from stone to smaller , but much more devastating iron balls meant that super - sized bores became unnecessary . The caliber of a 50 pound ball , for example , could be reduced from 28 to 18 cm when using an iron projectile instead . Thus , as early as the second half of the 15th century , further development in siege technology concentrated on the " Hauptbüchse " , and bombards largely disappeared from the leading artillery arsenal of the dukes of Burgundy . At about the same time super - sized bombards were phased out in Western Europe , the technology was transmitted to the Ottoman army by Orban , a Hungarian gunfounder , on the occasion of the Siege of Constantinople in 1453 . The extant Dardanelles Gun , cast by the Ottoman gunfounder Ali several years later , is assumed to have followed closely the outline of Orban ' s guns . A similar super - sized bombard was employed by the Ottoman navy aboard a carrack of possibly Venetian design at the Battle of Zonchio in 1499 . In India , there is a forge - welded Iron Cannon in Thanjavur , Tamil Nadu . This cannon was built during the reign of Raghunatha Nayak ( 1600 - 1645 AD ) , and it is said to be one of the largest cannons in the world . Artillery was used by Indian armies predominantly for defending against besieging armies . World Wars . The World War I German military were especially interested in the development of these superweapon s due to the need for the Schlieffen plan to march past a line of Belgian fortifications constructed specifically to stop such an invasion route . During the opening phases of the war , the Germans employed a 420 mm Krupp howitzer ( the Big Bertha ) and two 305 mm Skoda Mörser M . 11 mortars to reduce the famous fortresses of Liège and Namur . Their low overland mobility made them arrive later than the infantry at Liège , so several infantry assaults were made with heavy loss of life and generally little success . The guns arrived a few days later and reduced the forts at Liège one - by - one over a short period of a few days . Larger artillery after this opening period was generally limited to railway gun s , which had much greater mobility , or naval monitors ( two of the British Lord Clive class monitor s were fitted with an 18 inch ( 457 mm ) gun , and HMS General Wolfe fired at a railway bridge in Belgium ) . All of the major powers involved employed such weapons in limited numbers , typically between 280 and 305 mm ( 11 to 12 inches ) although some larger weapons were also used . 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 . Development continued during the inter - war era , although at a more limited pace as aircraft were expected to take over in the long - range bombardment role . Nevertheless the Germans built a handful of powerful Krupp K5 s and the great 800 mm ( 31 . 5 in . ) Schwerer Gustav and Dora . The latter had been designed specifically to defeat the Maginot Line , firing a 7 ton shell to a range of . Although their original role proved unnecessary , Gustav was used successfully to demolish several heavy fortifications , most notably those at Sevastopol . Dora was readied for combat at Stalingrad , but was withdrawn before it could be used . Gustav and Dora were the largest artillery pieces ( by caliber ) ever used in combat . Development may have ended there but for the ever - increasing Allied air power , which limited Hitler ' s options in terms of re - opening bombing attacks on London . This led to the development of the V - 3 " London Gun " or " " Hochdruckpumpe " " , fired from Mimoyecques in the Pas de Calais , about away . Two attempts to build underground bunkers for the huge weapons were thwarted by massive Royal Air Force bombing raids , which made further attempts futile . Two smaller prototype versions of the gun were used during the Battle of the Bulge . Modern developments . Canadian - born engineer 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 , and Bull turned to military designs , eventually developing the GC - 45 howitzer . 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 , terminating development , and the parts were confiscated by British customs after the Gulf War .