The Nazis clearly had a thing for big guns — these two 31.5-inch calibre German cannons were absolute behemoths. And in fact, they are the largest cannons the world has ever seen. Each of them had to be transported in several pieces, assembled, and then mounted on a prepared emplacement — a procedure that required around 4,000 men! The Nazis deployed an entire anti-aircraft regiment to protect them, along with special troops to guard against partisan attacks.
Of the two, only Gustav was put into active service. It fired 42 shots during the 1942 siege of Sebastopol — and the penetrative power of its huge shells, each weighing 11,000 pounds (4,800 kg), was enough to destroy an ammunitions dump protected by 100 feet (30 m) of rock. There were plans to equip it with rocket-propelled shells that could reach targets as far as 90 miles (145 km) away. Weapons expert Alexander Ludeke refers to them as “technological masterpieces” but says they were “basically a waste of materials, technological expertise, and manpower.”