Schwerer Gustav: The World’s Biggest Gun Ever Used in Combat

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The gigantic 80-cm kanone known as “Gustav” owed its origin to a 1935 Wehrmacht study into what would be needed to penetrate the thickness of concrete, being boasted of in French newspapers, in the newly completed Maginot Line. Krupp AG, a leading German steelworks and armaments manufacturer, were approached with a request to provide ballistic data for hypothetical guns of 70-cm, 80-cm, and 100-cm calibres.

In March 1936, Adolf Hitler visited the Krupp factory and asked Gustav Krupp (von Bohlen und Halbach), head of the Krupp organization, what type of weapon was needed to smash through the Maginot Line. Krupp, recalling the recent report, was able to answer Hitler’s question in some detail. Krupp explained that a 33.5 in (80 cm) railway gun could be constructed and would be able to defeat the Maginot Line. After Hitler’s visit, Krupp directed his design staff to begin the layout of such a weapon. Erich Müller was the head of the artillery development department at Krupp and began working on the gun’s design.

Schwerer Gustav cradle assymblyNicknamed Dora by its crew, the massive gun was broken down into 25 pieces and transported by rail to its firing location. Two gantry cranes were used to reassemble the gun. Here, the cradle is being positioned into the carrier. Note the three normal railroad tracks and the special track for the cranes.

In early 1937, Krupp met with Hitler and presented him with the design for the 33.5 in (80 cm) railway gun. Hitler approved of what he saw, and the German Army High Command (Oberkommando des Heeres) commissioned Krupp to build three guns under the designation 80 cm Kanone (E). However, the guns quickly became known as Schwerer Gustav (Heavy Gustav), named after Gustav Krupp. Hitler wanted the first gun to be ready by March 1940. After Hitler had departed, Gustav Krupp decided to take a gamble, and set his design team to work on the 80-cm model. In early 1937 he was in a position to lay a set of drawings before Hitler, who approved, and consented to the allocation of 10 million Marks for the project. The only stipulation being, that gun should be ready to demolish the Maginot Line defences by the spring of 1940.

The Schwerer Gustav was an absolutely huge weapon. The rifled barrel consisted of two halves, with the rear half covered by a jacket. The complete barrel was 106 ft 7 in (32.48 m) long, and its rifling was .39 in (10 mm) deep. Attached to the rear of the barrel was the cradle and breechblock. Mounted to the cradle were four hydraulic recoil absorbers. Trunnions held the gun’s cradle in two huge carriers and enabled the barrel to be elevated from 0 to 65 degrees. Each carrier was supported by four railroad trucks: two in the front and two in the rear. Each of the eight trucks was made up of five axles, giving the Schwerer Gustav a total of 80 wheels that were carried on two parallel sets of railroad tracks. The gun used a diesel-powered generator to provide power to run its systems. The Schwerer Gustav was 155 ft 2 in (47.30 m) long, 23 ft 4 in (7.10 m) wide, and 38 ft 1 in (11.60 m) tall. The barrel, cradle, and breech weighed 881,848 lb (400,000 kg), and the complete gun weighed 2,976,237 lb (1,350,000 kg).

This image gives a good view of the tracks needed to assemble the Schwerer Gustav. One pair of D 311 locomotives is positioned in front of the gun.

In addition to needing parallel tracks, the Schwerer Gustav required its track to be curved up to 15 degrees. The gun had no built-in ability to traverse, so horizontal aiming (azimuth) was accomplished by moving the entire gun along the curved track. Extra bracing was added to the inside rail of both tracks along the shooting curve. This bracing helped prevent the tracks from being damaged due to the gun’s recoil. A massive effort was needed to transport and set up the Schwerer Gustav for firing.

The gun was broken down and transported on 25 freight cars, which did not include crew or supplies. Near where the gun was to be deployed, a spur line was laid from the main rail line. Three parallel tracks were then laid where the Schwerer Gustav was to be assembled. Two of the tracks supported the gun, and the third track allowed for parts and equipment to be brought in. A single rail was laid on both sides of the three parallel tracks. These widespread rails were for two gantry cranes to take parts from the third track and move them in position to assemble the Schwerer Gustav. Two parallel tracks extended from the assembly point to the firing position of the Schwerer Gustav. Dirt was piled up high on both sides of the double track to protect the gun from attack and allow it to be covered by camouflage netting. It took around 250 men 54 hours to assemble the Schwerer Gustav, and it took weeks for 2,000 to 4,500 men to lay the needed tracks and prepare the gun’s firing position. In addition, two Flak (Flugabwehrkanone or air defense cannon) battalions were needed to protect the gun from an aerial assault.

Two types of shells were fired from the Schwerer Gustav: armor piercing (AP) and high explosive (HE). The AP rounds were 11 ft 10 in (3.6 m) long and were fired with 4,630 lb (2,100 kg) of propellant. The AP round was made of chrome-nickel steel. It weighed 15,653 lb (7,100 kg) and carried 551 lb (250 kg) of explosives. The AP shell had a muzzle velocity of 2,362 fps (720 m/s) and a maximum range of 23.6 miles (38 km). At maximum range, the AP projectile reached an altitude of around 39,370 ft (12 km) and was in the air for two minutes. The HE ammunition was around 13 ft 9 in (4.2 m) long and was fired with 4,938 lb (2,240 kg) of propellant. The HE rounds weighed 10,582 lb (4,800 kg) and carried 1,543 lb (700 kg) of explosives. The HE shell had a muzzle velocity of 2,690 fps (820 m/s) and a maximum range of 29.2 miles (47 km). Upon impact, the HE projectile created a crater some 33 ft (10 m) wide and deep. The muzzle velocity for both the AP and HE shells was over twice the speed of sound, and both were fitted with an aluminum alloy ballistic nose cone. Spotter aircraft were used to direct the gun’s fire and assess the results.Krupp built special diesel-electric locomotives to move the Schwerer Gustav into firing position and to transport supplies. These locomotives were designated D 311, and two were paired together to act as a single unit, for a total of four engines to move the gun. Each locomotive was powered by a 940 hp (700 kW) six-cylinder MAN diesel engine. The engine ran a generator that provided power to traction motors mounted on the locomotive’s bogies. Ammunition was delivered via the twin rails behind the Schwerer Gustav. Hoists on the back of the gun would lift the ammunition to the firing deck. The shell was hoisted up one side of the gun, and the powder bags and a brass obturation case were hoisted up the other side. A hydraulic ram loaded the shell into the breach, followed by the powder bags and the case. Once loaded, the gun was raised into firing position. It took 20 to 45 minutes to load the gun and prepare it for firing. Only 14 to 16 shots could be fired each day.

world's largest railway gunThe largest caliber rifled weapon ever to be used in battle, these 80cm railway siege guns had extremely heavy ammunition and required a battalion of 30 men to manage it.

The manufacture of the cannon proved even harder than had been anticipated. Forging and machining the massive barrel posed many difficult problems and the spring of 1940 came and went without the 80-cm gun being completed. Ultimately the Maginot line was simply outflanked by the German Army rather than demolished. Apart from Hitler nobody on the unenthusiastic German General Staff really missed having the wonder weapon.

Towards the end of 1940 the gun barrel was eventually ready and was test fired for the first time on the Hillersleben range near Magdeburg early in 1941. Finally, about a year later, the remainder of the equipment was ready. Taken to the Rugenward range on the Baltic coast of Pomerania, it was assembled and given its final firing tests in the presence of Hitler. Afterwards Krupp presented the Fuhrer with the gun free of charge as his personal contribution to the war effort. The gun was given the name of “Schwere Gustav” in honour of its originator, but the German artillerymen, with a little less respect, soon irreverently began calling it “Dora” (which is why, for a number of years, it was assumed there were two such weapons).

Although termed a railway-gun, the sheer size of Gustav meant that it actually traveled in sections to meet the loading gauge on German railways. Obviously it could not be transported in one piece. The gun itself was broken down into five units; breech ring and block, the barrel in two halves, the barrel jacket, the cradle and the trunnions. The rest of the mounting was split lengthwise so that as well as being dismantled from the top down, it was also broken into two halves for movement. All these components were carried on special flat-wagons, except for the bogie units which ran on their own wheels.

Gustav eventually went to war at the siege of Sevastopol in July 1942. The whole process of assembling Gustav’s 1,329 tons took about three weeks and a force of 1,420 men commanded by a Major-General. When fully assembled it would be 141 feet long, 23 feet wide, and the axis of the barrel some 25 foot above the track. A special four-track section had to be laid to put the gun into action; on the inner tracks the gun bogies were assembled and linked together, and on the outer pair ran a gantry crane for assembling the rest of the weapon. Various parts of the mounting were then built up on top of the bogies; the barrel was assembled by inserting the rear half into the jacket and then fitting the front half on and locking everything together with a massive junction nut. The barrel was then fitted into the cradle and the whole assembly hoisted up and lowered onto the mounting. After this the breech ring was fitted to the end of the barrel by another huge nut and the 20-ton breech block slid into place.

Once ready it opened fire on the Soviet fortifications, within the besieged city, with 4.7-ton high-explosive shells effective to a maximum range was 29 miles. With 7-ton concrete-piercing shells a range of 23 miles was achieved, and one such shell is reported to have penetrated 100-foot of earth before detonating inside an underground ammunition store. Some fifty or so of these massive shells were fired into Sevastopol causing immense damage.

After Sevastopol, Gustav trundled out of the lime-light. It was taken off to besieged Leningrad, but the Russians had other ideas and had pushed the German army back before the Gustav could be made ready. Its only other recorded appearance was outside Warsaw in 1944 when some 30 shells were fired into the city during the abortive rising. After that Gustav vanished. Numerous reports of its discovery in pieces, its scrapping, its capture or abandonment have been suggested but none of them stand up to very close examination; spare barrels and ammunition were found, but the gun itself was never seen again (Despite some reports that it was found wrecked on its special train by a US army unit in Bavaria at the end of the war). It seems likely that it was simply scrapped some time during late 1944.

Links & Reference Sources

The Heavy Gustav, Hitler and generals inspecting the largest caliber rifled weapon ever used in combat, 1941
Krupp 80 cm Kanone Schwerer Gustav (Dora) Railway Gun
80 cm Gustav Railway Gun
Hitler’s Doomed Schwerer Gustav: Largest Gun Mankind Has Ever Built

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