The Largest Self-Propelled Artillery Piece in History, The Karl-Gerat, World War II,
A massive mortar constructed for the German Army during World War II, the Karl-Gerat is the largest self propelled artillery piece in history. Built by Rheinmetall, seven of these behemoth guns were produced between 1941 and 1945. Weighing in at 142 tons, the gun itself was 24 inches in caliber and could fire a 4,800 lb shell around 6 miles. More importantly it was mobile, an important feature due to the mobile nature of warfare in WWII Europe. For the most part the Karl-Gerat guns wrecked havoc in Eastern Europe, being used to destroy the fortifications of Brest-Litvosk Fortress and playing a role in the Siege of Sevastopol. They were also used during the Battle of the Bulge, the Warsaw Uprising, and the Remagen Bridgehead.
While the Karl-Gerat was certainly intimidating and deadly, they had a weakness that made them sitting ducks in combat. While they were mobile, they were not that mobile. Powered by a 12 cylinder Daimler-Benz gasoline or diesel engine, the gun was transported on a caterpillar tracked undercarriage. A whole team of vehicles as well as a dedicated crew was needed to service the gun; a crane for loading the gun, several converted tanks to carry ammunition, a fleet of trucks, and a heavy trailer. For long distance transportation the gun had to be disassembled by the crane and stowed on the heavy trailer, otherwise the gun could only move at around 6 miles per hour. It was not uncommon for the gun to be disassembled when crossing bridges or certain types of terrain because the gun and carriage was too heavy. Often the Karl-Gerat could not make turns lest it throw a track. Another weakness was that the massive recoil of the gun often threw the entire assembly of target, meaning the gun had to be re-zeroed after every shot.
By the end of the war two had been destroyed by enemy forces. Others were captured by the US Army and the Red Army. Both conducted numerous tests of the weapons but determined them to be impractical for future warfare and scrapped. Of the seven only two still exist, being housed at the Kubinka Tank Museum in Russia.
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An early example of a self-propelled gun, the gun carrier “Dublin" moves toward the front with a 6-inch howitzer and its crew. Although the howitzer could be fired without having to be removed from the carrier, the carriers were also used with the 60-pdr Mk. Is, which had to be removed to fire.