Schwerer Gustav – The Largest Gun Ever Built

Schwerer Gustav, or the “Heavy Gustav,” was the largest and most powerful gun used in World War II. It was initially commissioned by Hitler to destroy the French Maginot Line; however, it was actually only used extensively in the siege of Sevastopol on the Eastern Front. Dismantled by the Germans before losing the conflict, the gun was the heaviest piece of mobile artillery ever built and had the greatest caliber of any rifled weapon used in war. The raw power came with a price. Its 7-tonne shells could break through over 7-meters of reinforced concrete, but 500 people were needed to fire it, and about 4,000 more were required to protect and operate it on the battlefield.

The Maginot Line

In 1934 Adolf Hitler already knew he would be invading France. The French, however, saw a German advance coming and started building the Maginot Line. The row of fortifications along the Franco-German border was intended to divert any upcoming invasion to Belgium, which would be protected by several divisions of the French Army. That way, they hoped to avoid replicating the damage and destruction of World War One to French territory.

The fortifications included block houses, rail lines, and bunkers. The barrier was extensive and comprehensive, seemingly impenetrable.

Because of these defenses, Hitler was left in need of a powerful new weapon that could do what no other existing weapon could…

Development

The Oberkommando des Heeres, the German Army High Command, reached out to the Essen weapons producer Friedrich Krupp AG in 1934 to commission a gun that could take down the forts along the Maginot Line. The main requirement was that the shells needed to go through a meter of steel armor plate or seven meters of reinforced concrete from a significant distance to prevent compromising said weapon.

Krupp engineer Erich Müller was put in charge of the project, and his estimates led him to the conclusion that this new weapon needed to be bigger and stronger than anything built before.

Müller’s calculations established that his team needed to create an 80 cm caliber cannon capable of firing a 7-tonne projectile from a 30-meter long barrel. He expected the weapon to weigh over 1,000 tonnes, which meant moving and handling it would be a challenge.

The Krupp team proposed twin sets of railway tracks to facilitate the movement of the cannon. Similar to smaller railway guns, the mount itself would only move the barrel up or down. Targeting the weapon would mean moving it along a curve in the railway line.

They made plans for different calibers between 85 cm and 1 m presented in the proposal to the Oberkommando des Heeres. Although traditional German weapons manufacturing practices meant that Krupp offered to make the first of these guns for free (with a price tag only negotiated if more were required) the OKH made no official commitment to obtaining it.

The project was on standby until Hitler visited Essen in March of 1936 and asked about the feasibility of building the massive cannon. After talks with Krupp, they began working on the design of an 80 cm caliber model. The plans were formalized, and development started in early 1937.

Schwerer Gustav

Production on the Schwerer Gustav commenced halfway through 1937. Although 1940 was set as a completion date, logistical issues with producing the massive sheets of steel needed pushed the start back.

A test model was ready in late 1939, which Krupp sent to Hillersleben for testing. During the tests, the gun was able to penetrate the meter of armor plate and the seven meters of concrete with a single shot from a high elevation.

Testing was completed in 1940, by which time the carriage had undergone several modifications. Hitler and Alfried Krupp met at that Rügenwalde Proving Ground in 1941 for confirmation of the Schwerer Gustav’s capabilities.

The Oberkommando des Heeres placed an order for two of these cannons. The first commissioned gun was fired for the first time on September 10th from a makeshift carriage. It was then tested in Poland using the 7,100-kilogram shell at a distance of nearly 40-kilometers from the target.

The Schwerer Gustav was an impressive weapon. The barrel was more than 100 feet long, longer than any other gun barrel at the time, and its body was bigger than any Allied or Axis tank.

The gun was mounted on a chassis with eight bogies (undercarriages) that had to be transported along two parallel railway tracks. The bogies gave the weapon a total of 80 wheels. The shells themselves were taller than two soldiers stacked on top of each other and weighed an intimidating 20,000 pounds. While this was necessary to pierce the barriers at the Maginot Line, it meant that multiple soldiers had to be involved in loading the Schwerer Gustav.

This first gun was free for the German Army, but the second one commissioned along with it had a price tag of seven million Reichsmark…

In Action

The enormous new German gun was not ready by the time Hitler needed it to break the Maginot Line, so his army had to take France without using it. Despite his previous belief that an extraordinary weapon would be necessary for that conflict, the Germans took over France with relative ease because the German troops overwhelmed the defensive forces.

Even though the original goal of the Schwerer Gustav had been accomplished without it, Hitler still wanted his new toy to be used on the battlefield. He saw the siege of Sevastopol as an opportunity to use it and display its grandeur before his enemies. The Heavy Artillery Unit E 672 was sent to Crimea along with the railway gun. The train carrying the weapon itself was 25 cars.

In early March, the train reached the Isthmus of Perekop, where it waited until April while the special railway for the gun was built. In April, the Schwerer Gustav was placed on the new tracks going from Simferopol to Sevastopol.

The gun was successfully used during the siege, its first time in combat. It took five weeks to get it into firing position, with input and assistance from 4,000 people. It began shooting on June 5th, with 500 soldiers participating in the firing process.

By the time Sevastopol fell on July 4th, the city had been destroyed. The Schwerer Gustav had fired 48 rounds. It shot at several valuable targets, including a munitions depot 98 feet underground that collapsed due to the shot.

The barrel ended up in a precarious state due to its continuous use since testing. It was sent back to Essen, and the gun received a spare barrel that had been kept inside the train.

Soon after the battle was won, the colossal railway cannon was dismantled so it could be transported. The German Army had it sent to the north of the eastern front so it could be used against Leningrad in a planned attack.

The Schwerer Gustav spent the winter near the Soviet city… before it could be used again, the attack was called off.

Further Development

Three additional versions were either built or planned after the design of the Schwerer Gustav.

The second gun produced, and the only other one used in battle was named Dora, after Erich Müller’s wife. It cost seven million Reichsmark, equivalent to 24 million U.S. dollars in 2015.

Dora was deployed to the west of Stalingrad halfway through August of 1942 but was not ready for combat until September 13th. Since the Soviets were about to encircle the Germans soon after, the German troops decided to retreat, taking the mighty weapon with them.

The Langer Gustav was a second-generation cannon that was destroyed by British bombings over Essen while it was under construction. The gun would have had a 52 cm caliber and a 43-meter long barrel. Its shells weighed 1500 pounds and could shoot from 118 miles away. This meant that the Germans could have shot at London all the way from Calais in France.

The third cannon was designed as part of a 1,500 tonne, self-propelled tank. The Landkreuzer P. 1500 Monster was supposed to carry an 80 cm caliber gun, two heavy howitzers, and MG 151 autocannons to target aircraft.

While some reports claim that the project was canceled by Albert Speer before a prototype was made, others have argued that the lack of evidence pointing at the development of this tank was just an urban myth.

If it were real, and it had been built, the tank would have been 500 tonnes heavier than the heaviest tank ever built, the Panzer VIII Maus.

Massive Potential, Massive Headache

After only limited use on the battlefield, the German Army realized just how complicated it was to operate the Schwerer Gustav.

One of the main problems was the considerable number of soldiers needed to fire each round of ammo. This meant that all those soldiers would be focused on single shots rather than playing multiple roles on the front. 2,000 people were needed to fire the Gustav cannon, the majority of them providing air cover rather than operating it.

Additionally, assembling the five parts of the gun would take around four days. Transporting the gun similarly required multiple days and several troops to avoid having the massive railway weapon from being hit by a plane. Since movement was limited to specially designed tracks, difficult terrain made it impossible to transport, and the rails made it easy for the Allies to predict German positions.

Another major issue with Schwerer Gustav was the rate of fire, since calibrating the cannon required several hours, it could only shoot about 14 rounds a day.

The last nail in the Schwerer Gustav’s coffin was the high cost of producing its shells, which had to be deprioritized with a deeply invaded Germany and high demand for tanks.

The Third Reich’s army eventually decided to retire Schwerer Gustav for the last days of the war.

Dismantling

By April 14th, 1945, the Soviet Union’s Vienna Offensive had been successful, and it was evident that American troops would soon be taking over the country. That same day the leadership in charge of Schwerer Gustav decided to dismantle the cannon to prevent the Allied Forces from capturing and using it.

The weapon’s ruins were found on April 22nd in a forest area near Auerbach and Chemnitz. After being studied by Soviet weapons specialists, it was sent to Merseburg and subsequently lost.

Dora was destroyed on April 19th, and the wreckage was discovered by American troops. Today part of those ruins are housed in the Dresden Military History Museum of the Bundeswehr.