Schwerer Gustav (English: Heavy Gustav) and Dora were the names under which the German 80 cm K (E) railway guns were known. They were developed in the late 1930s by Krupp in order to destroy large, heavily fortified targets. They weighed nearly 1,344 tons, and could fire a shell that weighed more than 7 tons at distances up to 37 km (23 miles). Designed in preparation for World War II, they were intended to be used against the Maginot Line. But instead of a frontal assault, the Wehrmacht outflanked the line during the Battle of France. One of the guns was used in Russia at the siege of Sevastopol during Operation Barbarossa. It was destroyed near the end of the war to avoid capture. It is the largest calibre rifled weapon in the history of artillery and fired the heaviest shells of any artillery piece. It is only surpassed in calibre by the American 36-inch Little David mortar and a handful of earlier siege mortars which all fired smaller shells. In 1934 the German High Command (OKH) gave to the firm of Krupp of Essen, Germany the problem of designing a gun to destroy the fortresses of the French Maginot Line which was then nearing completion. The gun had to be able to punch through 7 meters of reinforced concrete and an armoured plate 1 meter thick, and do this from a range that kept it out of reach of enemy artillery. Krupp engineer Dr. Erich M�ller calculated that the task would require a weapon with a calibre of around 80 cm, firing a projectile weighing 7 tonnes from a barrel 30 meters long. As such the weapon would have a weight of over 1000 tonnes. The size and weight meant that to be at all movable it would need to be supported on twin sets of railway tracks. In common with smaller railway guns, the only barrel movement on the mount would be elevation, traverse being managed by moving the weapon along a curved section of railway line. Krupp prepared plans for calibres of 70 cm, 80 cm, 85 cm, and 100 cm. Nothing further happened until March 1936, when Hitler visited Essen during which he enquired into the giant guns' feasibility. No definite commitment was given by Hitler, but design work began on an 80 cm model. The resulting plans were completed in early 1937 and approved. Fabrication of the first gun started in the summer of 1937. However, producing such a large weapon proved difficult and it became apparent that the original completion date of spring 1940 would not be met. Krupp built a test model in late 1939 and sent it to the Hillersleben firing range for testing. Penetration was tested on this occasion. Firing almost vertically, the gun was able to penetrate the specified 7 meters of concrete and 1 meter of armour plate [1]. After the tests were completed in mid-1940 the gun and carriage were removed and probably scrapped. Alfred Krupp personally hosted Hitler and Albert Speer (Minister of Armaments) at the Ragenwald Proving Ground during the formal acceptance trials of the Gustav Gun in the spring of 1941. The outcome of the tests resulted in orders for two guns. The first round was test-fired from the commissioned gun barrel on September 10, 1941 from a makeshift gun carriage on the Hillersleben firing range. In November 1941, the barrel was taken to R�genwald where 8 further firing tests took place using the 7,100 kg armor-piercing (AP) shell out to a range of 37,210 meters. In combat, the gun was mounted on a specially designed chassis, supported by two bogies on two parallel sets of railway tracks. Each of the bogies had 20 axles, giving a total of 40 axles (80 wheels). Krupp christened the gun Schwerer Gustav (Heavy Gustav) after the senior director of the firm, Gustav Krupp von Bohlen und Halbach. The ammunition for the gun consisted of a heavy concrete-piercing shell and a lighter high-explosive shell. A super-long-range rocket projectile was also planned with a range of 150 km that would require the barrel being extended to 84 m. This rocket projectile would have enabled the bombardment of England. In keeping with the tradition of the Krupp company, no charge was made for the first gun. However, they did charge 7 million Reichsmark for the second gun Dora, named after the senior engineer's wife.