The biggest was the “Gustav Gun,” built in Essen, Germany in 1941 by the firm of Friedrich Krupp, A.G. Upholding a tradition of naming heavy cannon after family members, the Gustav Gun was named after the invalid head of the Krupp family ­Gustav Krupp von Bohlen and Halbach. The strategic weapon of its day, the Gustav Gun was built at the direct order of Adolph Hitler for the express purpose of crushing Maginot Line forts protecting the French frontier. To accomplish this, Krupp designed a giant railway gun weighing 1344 tons with a bore diameter of 800mm (31.5″) and served by a 500-man crew commanded by a major general.

The largest gun ever built had an operational career of 13 days, during which a total of 48 shells were fired in anger. It took 25 trainloads of equipment, 2000 men and up to six weeks to assemble. It seem unlikely that such a weapon will ever be seen again.
The 80-cm K (E), for all its size and weight, to say nothing of its ‘overkill’ firepower, went into action on only one occasion. It was originally intended to smash through the extensive Maginot Line forts but when the campaign in the West took place in 1940 the 80-cm K (E) was still in the Krupp workshops at Essen and, in any event, the German army bypassed the Maginot Line altogether. Thus when the 80-cm equipment had completed its gun proofing trials at Hillersleben and its service acceptance trials at Rugenwalde there was nothing for the gun and its crew to do. To justify the labour and effort of getting the huge gun and its entourage into action, the potential target had to justify all the bother involved, and there were no really large fortification lines left in Europe for the gun to tackle. The two major fortification systems, the Sudetenland defences and the Maginot Line, were both in German hands and it seemed that the 80-cm K (E), or ’schwere Gustav’ (heavy Gustav) as it became known, was redundant even before it had fired an aggressive shot.