One big bang!
In 1939, Adolf Hitler needed to figure out how to get past the French Maginot line, a 1500km defensive wall of fortifications, tank barriers, artillery and machine gun nests running along the French-German and French-Italian borders. Before he figured out to simply run around the line via Belgium, Hitler schemed to destroy it outright…
To that end, he recruited the Friedrich Krupp A.G. company of Essen, Germany, to build him a weapon capable of doing so. By 1941, the Krupp company had designed and built the largest gun of all time, the ‘Gustav Gun.’
via The Presurfer