Schwerer Gustav, or the “Heavy Gustav,” was the largest and most powerful gun used in World War II. It was initially commissioned by Hitler to destroy the French Maginot Line; however, it was actually only used extensively in the siege of Sevastopol on the Eastern Front. Dismantled by the Germans before losing the conflict, the gun was the heaviest piece of mobile artillery ever built and had the greatest caliber of any rifled weapon used in war. The raw power came with a price. Its 7-tonne shells could breakthrough over 7-meters of reinforced concrete, but 500 people were needed to fire it, and about 4,000 more were required to protect and operate it on the battlefield…