Schwerer Gustav Was the Largest Gun Ever Made

Schwerer Gustav, stood as a formidable weapon of war. A hallmark of Second World War artillery was the development of increasingly large and high-caliber cannons.

The 36-inch (914 mm) Little David, built for the American army, was another such weapon. Designed to attack Japanese bunkers at the end of WWII, this mortar was the largest in the world but never saw combat, as Japan surrendered before its deployment.

Hitler initiated the creation of Schwerer Gustav before WWII started, envisioning it as a tool for the German Army to break through the Maginot Line during the invasion of France.

Although its construction missed the timing of the French invasion, it participated in various actions during the war. Despite years of development and construction, Schwerer Gustav’s overall impact on the war was minimal. Despite its impressive size and power, the weapon’s end was ignominious.


Maginot Line

In the 1930s, France built the Maginot Line, a series of fortifications and obstacles to defend against invasions from the east, particularly Germany. The Maginot Line aimed to act as an unbreakable defensive barrier. In response, countries typically race to develop technologies to overcome new defense systems.

A massive 31 inch/800 mm shell from the German 'Dora' railway gun next to a Jeep.... shells weighing 7 tons and had a range of 29 miles/47 km…
A massive 31 inch/800 mm shell from the German ‘Dora’ railway gun next to a Jeep…. shells weighing 7 tons and had a range of 29 miles/47 km…

German Wehrmacht (combined armed forces) planners, after examining details of the Maginot Line fortifications published in French newspapers, realized they lacked weapons capable of breaching these fortifications.

In 1935, the Wehrmacht asked Friedrich Krupp AG (Krupp), an Essen-based heavy industry conglomerate in Germany, to produce ballistics reports for guns firing shells from 27.6 to 39.4 inches (70 to 100 cm).

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Their objective was a gun that could operate beyond enemy artillery range and penetrate 23 feet (7 meters) of reinforced concrete or 3 feet (1 meter) of steel armor. Krupp conducted the necessary calculations and provided the information, but did not proceed further.

In March 1936, Adolf Hitler visited the Krupp factory and inquired with Gustav Krupp (von Bohlen und Halbach), the head of the Krupp organization, about the type of weapon needed to break through the Maginot Line.

Remembering the recent report, Krupp detailed that a 33.5-inch (80 cm) railway gun could be built to defeat the Maginot Line. Following Hitler’s visit, Krupp instructed his design team to start planning such a weapon, and Erich Müller, head of Krupp’s artillery development department, began working on the gun’s design.

Design Was Approved

In early 1937, Krupp presented Adolf Hitler with the design for a 33.5-inch (80 cm) railway gun. Hitler approved, and the German Army High Command (Oberkommando des Heeres) tasked Krupp with building three guns, designated as 80 cm Kanone (E). These guns quickly gained the name Schwerer Gustav (Heavy Gustav), after Gustav Krupp. Hitler wanted the first gun ready by March 1940.

The Germans are known to have had four of these long-range weapons.
It was a marvel of engineering – caliber of 800mm, weight of 1350 tons

The Schwerer Gustav was a colossal weapon. Its rifled barrel, consisting of two halves with the rear half encased in a jacket, stretched 106 feet 7 inches (32.48 meters) long with .39-inch (10 mm) deep rifling. A cradle and breechblock attached to the barrel’s rear, and four hydraulic recoil absorbers mounted to the cradle.

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Trunnions anchored the gun’s cradle in two massive carriers, allowing barrel elevation from 0 to 65 degrees. Each carrier rested on four railroad trucks, two at the front and two at the rear, with each of the eight trucks comprising five axles. This gave the Schwerer Gustav a total of 80 wheels on two parallel sets of railroad tracks.

The gun operated with power from a diesel generator. Overall, the Schwerer Gustav measured 155 feet 2 inches (47.30 meters) in length, 23 feet 4 inches (7.10 meters) in width, and 38 feet 1 inch (11.60 meters) in height. The barrel, cradle, and breech alone weighed 881,848 pounds (400,000 kg), and the entire gun weighed 2,976,237 pounds (1,350,000 kg).

4,500 men

Besides requiring parallel tracks, the Schwerer Gustav needed its track to have up to a 15-degree curve. Since the gun couldn’t traverse on its own, operators aimed it horizontally (azimuth) by moving it along this curved track.

To prevent damage from the gun’s recoil, extra bracing reinforced the inside rail of both tracks along the shooting curve. Setting up the Schwerer Gustav for firing demanded a massive effort.

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Crews broke down the gun into parts and transported it on 25 freight cars, excluding the crew and supplies. Near the deployment site, they laid a spur line from the main rail line. Then, they constructed three parallel tracks at the assembly site: two supported the gun and one brought in parts and equipment.

Alongside these tracks, they laid a single rail on both sides for two gantry cranes to move parts from the third track into position for assembling the Schwerer Gustav. Two parallel tracks led from the assembly area to the firing position. They piled dirt high on both sides of this double track for protection and camouflage netting concealment.

Assembling the Schwerer Gustav took about 250 men 54 hours. Preparing the tracks and the firing position required weeks of work by 2,000 to 4,500 men. Additionally, two Flak (Flugabwehrkanone or air defense cannon) battalions were necessary to defend the gun against aerial attacks.

Diesel-Electric Locomotives

Krupp manufactured special diesel-electric locomotives to maneuver the Schwerer Gustav into its firing position and to haul supplies. These locomotives, designated D 311, worked in pairs as a single unit, requiring a total of four engines to move the gun.

Insane size

Each locomotive used a 940 hp (700 kW) six-cylinder MAN diesel engine to power a generator. This generator supplied electricity to traction motors on the locomotive’s bogies. Crews delivered ammunition to the Schwerer Gustav via twin rails positioned behind the gun. Hoists on the gun’s rear lifted the ammunition to the firing deck.

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They hoisted the shell up one side of the gun and the powder bags and a brass obturation case up the other. A hydraulic ram then loaded the shell into the breech, followed by the powder bags and the case. Once loaded, operators raised the gun into its firing position. Loading the gun and preparing it to fire took between 20 to 45 minutes, limiting its firing capacity to only 14 to 16 shots per day.

A Range of 29.2 miles

The Schwerer Gustav fired two types of shells: armor-piercing (AP) and high explosive (HE). Crews fired the 11-foot-10-inch (3.6-meter) long AP rounds with 4,630 pounds (2,100 kg) of propellant. Made of chrome-nickel steel, these rounds weighed 15,653 pounds (7,100 kg) and contained 551 pounds (250 kg) of explosives.

Casings that held the propellant, those drums on the right are 44 gallon drums.
Casings that held the propellant, those drums on the right are 44 gallon drums.

They achieved a muzzle velocity of 2,362 feet per second (720 meters per second) and a maximum range of 23.6 miles (38 km). At maximum range, the AP projectile reached approximately 39,370 feet (12 km) in altitude and stayed airborne for two minutes.

The 13-foot-9-inch (4.2-meter) long HE ammunition, fired with 4,938 pounds (2,240 kg) of propellant, weighed 10,582 pounds (4,800 kg) and carried 1,543 pounds (700 kg) of explosives. These rounds had a muzzle velocity of 2,690 feet per second (820 meters per second) and a maximum range of 29.2 miles (47 km), creating craters about 33 feet (10 m) wide and deep upon impact.

Both AP and HE shells, traveling over twice the speed of sound, were fitted with an aluminum alloy ballistic nose cone. Spotter aircraft directed and assessed the gun’s fire.

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Construction of the Schwerer Gustav began in spring 1937, but forging the massive, complex barrel caused significant delays. By 1939, Alfried Krupp (von Bohlen und Halbach) started assuming leadership of the company as his father’s health declined.

Late that year, testing commenced on sample components, with the gun’s AP projectile successfully penetrating 23 feet (7 meters) of concrete or 3 feet (1 meter) of steel. It became clear that the Schwerer Gustav would not meet Hitler’s March 1940 deadline.

Schwerer Gustav Worn Out

The Schwerer Gustav saw use for three additional days before running out of ammunition. During this period, it is thought to have fired a total of 47 shells at the city, resulting in significant wear to its barrel. Some sources suggest the barrel, designed for a 300-round lifespan, was the same one used for 250 test rounds.

Gustav was eventually captured by US troops and cut up

Others argue that the barrel was new, theoretically capable of 100 shots before wearing out, yet showed signs of wear after just 15 shots. Regardless, crews replaced the worn barrel of the Schwerer Gustav with a spare, and sent the original barrel back to Germany for repairs.

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Of the 47 rounds fired, only 10 landed within 197 feet (60 meters) of their intended target, with the most inaccurate shot missing its mark by 2,428 feet (740 meters). Nevertheless, each enormous shell inflicted massive damage around its impact area.

Schwerer Gustav

Sevastopol fell on July 4, 1942, and several weeks after, Gustav Krupp personally gifted the first Schwerer Gustav to Hitler as a sign of his support and allegiance to the Third Reich. Krupp company planned to charge only for subsequent guns.

The Schwerer Gustav was then moved and set up for a planned offensive against the besieged Leningrad. Although the gun was assembled and ready to fire, the operation was called off, leading to its disassembly and return to Rügenwalde.

The firing chamber of the 800mm railway gun. Poised to be transformed into scrap metal. Loading one of its 7-ton shells took approximately 45 minutes.
The firing chamber of the 800mm railway gun. Poised to be transformed into scrap metal. Loading one of its 7-ton shells took approximately 45 minutes.

After an overhaul and the fitting of an improved, lined barrel, the Schwerer Gustav underwent a test firing on March 19, 1943, at Rügenwalde. This event was attended by Hitler, Albert Speer, Alfried Krupp, and several other officials. They fired two shots, with the second shell landing 29.2 miles (47 km) away.

The gun was then disassembled and stored near Chemnitz, Germany, in September 1943. It remained there until April 14, 1945, when German troops destroyed it a day before US soldiers captured the area.

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The Soviets reportedly recovered parts of the Schwerer Gustav and transported them to Russia. The second Schwerer Gustav, reportedly completed but never deployed, was moved from Rügenwalde to Grafenwöhr, Germany, in March 1945 and destroyed on April 19, 1945.

Länger Gustav (Longer Gustav)

In November 1943, the Germans initiated plans to shell Britain from across the English Channel using a cannon. They decided to build the third Krupp 80 cm Kanone (E) specifically for this task.

Named Länger Gustav (Longer Gustav), this gun aimed to fire a 20.5-inch (52 cm) diameter projectile weighing 1,499 pounds (680 kg) over a distance of 99 to 124 miles (160 to 200 km) from a 157-foot (48 m) long barrel.

American forces, who found it being dismantled in the woods near Grafenwöhr, nicknamed it “Big Bertha.” However, the Germans referred to this gun — one of the two 800mm K(E) railway guns developed and produced by Krupp,

However, the gun suffered damage during a bombing raid while still under construction. In 1945, Allied troops discovered some components of the Länger Gustav at the Krupp factory in Essen.

In December 1942, Krupp proposed a self-propelled version of the 80 cm Kanone (E) called the Landkreuzer P. 1500 Monster. This massive vehicle, equipped with the same 31.5-inch (80 cm) main gun as the Schwerer Gustav, also featured two 5.9-inch (15 cm) sFH 18.1 L/30 field guns and several 15 mm MG151/15 cannons.

Albert Speer

Powered by four 2,170 hp (1,618 kW) nine-cylinder MAN M9V 40/46 diesel engines, the P. 1500 measured 137 feet 10 inches (42 m) in length, 59 feet 1 inch (18 m) in width, and 23 feet (7 m) in height.

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Weighing 3,306,930 pounds (1,500,000 kg), it required a crew of over 100, had a top speed of 9.3 mph (15 km/h), and a range of 31 miles (50 km). Albert Speer, the Minister for Armaments, cancelled the P. 1500 project in 1943 before any significant development occurred.

The shell weighed 7 tons

After the war, Alfried Krupp and Erich Müller, the gun’s designer, received 12-year prison sentences for crimes against humanity, including participation in plundering, devastation, and exploitation of occupied countries, as well as involvement in various war crimes. Krupp received a pardon after three years, while Müller was released after four years.

Schwerer Gustav Survivors

On April 14, 1945, a day before US troops arrived, German forces destroyed Schwerer Gustav to prevent its capture. Its remnants were found on April 22, 1945, in a forest 9.3 miles (15 kilometers) north of Auerbach and about 31 miles (50 kilometers) southwest of Chemnitz. In the summer of 1945, Soviet specialists examined the Schwerer Gustav, and in the autumn, they moved it to Merseburg, where the Soviets were collecting German materials.

Schwerer Gustav was not a battlefield weapon. It was used for bombardment of cities.
Schwerer Gustav was not a battlefield weapon. It was used for bombardment of cities.

In March 1945, the Germans transferred Dora to Grafenwöhr, where it was destroyed on April 19, 1945. American troops found the debris later, following the discovery of Schwerer Gustav’s ruins. This debris was scrapped in the 1950s.

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After the war, parts of the third gun were found in the Krupp production facilities in Essen. The largest collection of “Dora” artifacts is housed in the Military History Museum of the Bundeswehr in Dresden.

Was it Worth it

The construction of the Heavy Gustav is often criticized as a significant waste of time and resources. Indeed, in some respects, it was, although those defending Sebastopol might have a different view. However, if the Maginot Line had not been bypassed and if Gibraltar had been a viable target, Heavy Gustav could have played a major role in Germany’s war efforts. Many weapons that are now commonly used were once dismissed as ineffective.

On April 19, 1945, the Germans demolished a section of the second Schwerer Gustav to stop it from being captured. A US soldier standing beside the gun's barrel provides a sense of its immense size.
On April 19, 1945, the Germans demolished a section of the second Schwerer Gustav to stop it from being captured. A US soldier standing beside the gun’s barrel provides a sense of its immense size.

For example, Napoleon deemed the submarine useless, and General Haig labeled the machine gun as an ‘over-rated weapon’. Ultimately, Heavy Gustav never really got the opportunity to demonstrate its full potential against a target that matched its immense firepower.

Given the minimal tactical advantage it provided during the war, the massive investment in terms of manpower and finances seems unjustifiable. Nevertheless, Heavy Gustav served as a unique laboratory for studying heavy projectiles in flight, and the insights gained significantly advanced the fields of gunnery and ballistics. It stands as a remarkable feat of engineering.