Big Bertha: Krupp's 42 cm Howitzer That Smashed the Belgian Forts in 1914

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Rifled artillery made old masonry star forts obsolete, so France and Belgium buried their defenses in reinforced concrete with low steel cupolas, including Belgium's National Redoubt. Germany's Schlieffen Plan depended on crossing Belgium fast, and its largest 21-centimeter howitzer could barely mark the new forts. Inspired by Japan's use of 28-centimeter coastal guns at Port Arthur in 1904, Krupp first built the Gamma-Gerät, which weighed 150 tons, ran on special rails and needed a concrete foundation. The answer by 1911 was the M-Gerät: a 42-centimeter howitzer of 42.6 tons, split into five loads, towed by tractors on wheels fitted with broad steel plates at about 4.3 miles per hour.

Its high explosive shells weighed over a ton and carried delay fuses that let them bore up to 12 meters into the earth before detonating. From August 12, 1914 the forts around Liège collapsed, and Namur, Maubeuge and Antwerp followed within days. At Fort de Loncin the 25th shot detonated the main magazine, and General Gérard Leman was pulled unconscious from the rubble. By Verdun in 1916 the French had added sand layers to forts such as Vaux and Douaumont, so shells exploded short. Faulty shells began bursting in the barrels, crews fired by lanyard from cover, and three of four Beta-M-Gerät conversions blew up.

• German troops named the gun Dicke Bertha after Bertha Krupp, heiress of the firm that built it.
• A base plate with a spade dug into the ground replaced the concrete foundation and let the gun traverse 360 degrees.
• The guns still worked on the Eastern Front, where older Russian forts at Kaunas shattered like the Belgian ones.
• The two surviving guns went to the Aberdeen Proving Ground in Maryland after the war and were scrapped.
• The Big Bertha name is often confused with the Paris Gun, a railway gun that shelled Paris from 75 miles away.