The heaviest gun ever built was ordered by Hitler. He wanted the gun to be able to pierce a meter of steel, seven meters of concrete, or thirty meters of dense earth. The original target was the French Maginot Line, the fortifications which were nearly impervious to anything the Nazis had before the war.
Krupp responded by designing a 800 mm railway gun, mounted, due to its great weight, on double tracks. Its great weight also meant that it could only be turned by pushing it on curved railroad tracks. Preparing a firing position and assembling the gun, which was always transported in parts, took six weeks.
The gun fired two types of ammunition: a high-explosive shell containing a 700-kilogram explosive charge and an armor-tipped concrete-piercing projectile containing a 250-kilogram charge and capable of penetrating over 250 feet of reinforced concrete before exploding.
Due to the Krupp tradition of naming heavy cannon after family members (see Big Bertha), the first 800 mm gun was named Gustav after the head of the family, Gustav Krupp von Bohlen und Halbach, who initiated the project.
It is unclear whether Krupp ever manufactured a second gun of this caliber. It may be that the gun known as Dora was actually the original Gustav after being refitted. Dora was named after the chief engineer's wife. I will continue to refer to the 800 mm gun(s) used in the war as Dora, like most sources.
The original order was for three guns, but it is fairly certain that a third one was never finished.
The Maginot Line was bypassed and France had fallen in 1940 before any of these guns were finished, so new targets were sought. High Command's plans to use them against the British fortress of Gibraltar were scrapped after General Franco refused to allow firing the gun from Spanish soil.
While the gun was being demonstrated to Hitler and the Oberkommando des Heeres, Dr. Müller of Krupp told the Führer that it could be used against enemy armor. Panzer General Guderian was stunned by this statement, and replied to Hitler that, while the gun could indeed be fired at tanks, it would never be able to hit them.
Among the special equipment developed by Krupp to operate the gun was an entirely new railway engine, the diesel-electric D 311. It was designed to move Dora in pairs on the curved track to aim the gun, and because of this it had to be able to pull a vast load at very slow speeds.
In June 1942, Dora was used in battle for the first time, firing at the heavily fortified Crimean port of Sevastopol. Spotter aircraft noted the impressive performance of the gun. Fire from Dora and other heavy artillery destroyed Forts Stalin, Lenin, Molotov and Maxim Gorki. A single round from the Dora destroyed an ammunition dump, built under the Severnaya Bay and considered invulnerable to artillery by the Soviets, and a near miss capsized a large ship in the harbor. The barrel was worn out during the siege and replaced. It may have fired a total of 300 rounds during testing and near Sevastopol.
Dora was set up near both
Stalingrad and
Leningrad in late 1942, but in both cases it was hurriedly withdrawn to avoid capture (it would have been very bad publicity to have the Soviets capture the gun and use it against the Germans, even though it was of relatively little military significance).
Dora appeared again outside Warsaw during the September 1944 uprising, firing 30 rounds into the Warsaw Ghetto. After this, it was never used again. The blown-up remnants of a gun of this type were discovered in Bavaria by the Allies.
The 800 mm shells could destroy pretty much anything they hit. However, the gun was ludicrously expensive to build and maintain. First of all, it took a massive amount of steel to build, and the barrel wasn't good for more than a few hundred rounds. Also, the gun required more than a thousand troops to move, assemble, maintain and reload. And since it was such a huge target and could hardly be kept in secret when in use, it needed heavy air defense and could be destroyed by a single successful bombing raid. These factors made it an impractical weapon in war, especially since it was really only suited for destroying massive fortifications (although it could take out a city block with a single shot, normal heavy artillery could do this just as well, and cheaper), and there simply weren't any within range after France and Sevastopol were taken.
Dora was yet another example of the Nazis' obsession with equipment that was either much too heavy or much too advanced to be deployed in any practical manner.
Specifications:
- Caliber: 800 mm
- Range: 45 km (HE), 37 km (concrete-piercing)
- Rate of fire: 2 rounds per hour
- Weight of the shell: 4800 kg (HE), 7500 kg (concrete-piercing)
- Propellant: 1350 kg of smokeless powder
- Size of the shell: 800 mm x 3.75 m
- Muzzle velocity: 820 m/s (HE), 720 m/s (concrete-piercing)
- Weight: 1350 tons (the barrel alone weighed 400 tons)
- Barrel length: 32.5 m (40 times the caliber)
- Overall length: 43 m
- Width: 7 m
- Height: 12 m
- Maximum elevation: 53°
- Crew: 1420 (the main gun crew, who were required to reload the gun, numbered 500)
Sources:
http://www.worldwar.nl/secretweapons/secretgerman2.htm
http://www.5ad.org/gun.htm
http://www.vlewis.net/dora.html
http://palpatine.chez.tiscali.fr/Page13/page13.htm
http://www.cix.co.uk/~nrobinson/railgun/Railwayguns/German/Dora%20index.htm
http://www.cix.co.uk/~nrobinson/railgun/Railwayguns/German/Oil-Electric%20Engines-DORA.html
http://home.att.net/~berliner-ultrasonics/ordnanc2.html
http://www.geocities.com/CapeCanaveral/Lab/1167/edora.html