At the beginning of the last century, German industry was actively working on the creation of promising siege weapons of special power. In the event of a full-scale armed conflict, such weapons were to be used to destroy enemy fortresses and other fortifications. For several years, leading German companies have created a number of different samples of such systems. One of the most famous representatives of its class was the siege mortar Dicke Bertha.
The development of siege weapons was carried out by the forces of the Krupp concern, which by the beginning of the 20th century had become one of the world leaders in the field of artillery. In the first decade of the century, he developed several variants of large-caliber guns, the last of which was the so-called. 42 cm Gamma-Gerät. Based on the results of tests and refinements, it was decided to adopt this system. In 1913-18, the manufacturer built ten such 420 mm howitzers / mortars and handed them over to the customer. Subsequently, such weapons were actively used during the First World War.
The prototype "Big Bertha" is being tested. Photo Landships.info
In 1912-13, the German military department tried to determine the prospects for the developed weapons of special power. The Gamma product was of great interest to the army, but at the same time it had serious drawbacks. The gun was distinguished by its large mass and extremely strong recoil, which is why it had to be installed on a specially prepared concrete slab of appropriate dimensions. The deployment of such an artillery system lasted more than a week, and most of the time was spent on the hardening of concrete. As a result, the mobility of the gun, to put it mildly, left much to be desired.
The military ordered the serial production of 420-mm cannons, requiring the construction of the foundation, but at the same time they demanded to create a more mobile system with similar combat qualities. In 1912, an official order appeared for the creation of such an artillery complex. The new project was to be developed by a recognized industry leader - the Krupp concern. Max Draeger and Fritz Rausenberg were appointed as project leaders.
Initially, the gun did not have a shield. Photo Wikimedia Commons
Considering the importance of the work and the need to keep the project's goal secret, the development company assigned the project the symbol M-Gerät (“M device”). The name M-Gerät 14 was also used to reflect the year the design was completed. In addition, over time, the designation Kurze Marinekanone 14 ("Short naval gun of 1914") appeared. These designations were official and used in documents.
From the point of view of its role on the battlefield, a promising system was to become a siege weapon. At the same time, some characteristics make it possible to unambiguously clarify such a classification. The project proposed the use of a barrel with a length of 12 calibers. This barrel length corresponds to the generally accepted definition of a mortar. Thus, the army in the future was to receive super-heavy siege mortars.
Fully loaded mortar. Photo Kaisersbunker.com
A little later, the new project received the unofficial nickname Dicke Bertha ("Fat Bertha" or "Big Bertha"). According to the widespread version, the gun was named after Berta Krupp, who was one of the leaders of the concern at that time. According to another, less well-known version, the witches had in mind the writer and activist of the pacifist movement Bertha von Suttner. However, there is no unequivocal evidence in favor of this or that version. It is possible that the new weapon was named Bertha without any connection with a specific person, simply using one of the common female names. One way or another, the promising weapon was widely known under the name Dicke Bertha, while official designations were more often used in documents than in living speech.
In accordance with the customer's requirements, the new weapon had to be similar to the existing model. However, for a number of reasons, it had to be developed from scratch, albeit using some of the existing ideas and solutions. The result of this approach should have been the appearance of a 420-mm siege gun on a towed wheeled carriage. The large caliber, the need to ensure high structural strength and the requirements for special equipment led to the formation of an unusual appearance of the gun. Externally, "Fat Bertha" was supposed to resemble other existing towed guns of smaller calibers. At the same time, there were major differences in layout and other aspects.
Demonstration of the weapon to the military. Photo Landships.info
For a weapon of special power, it was necessary to develop a towed wheeled carriage with appropriate characteristics. The main element of the gun carriage was the lower machine, which was responsible for positioning and transmitting the unquenched recoil impulse to the ground. The main part of the lower machine was a large T-shaped unit, which had fasteners for mounting all other equipment. On its front part, fasteners were provided for installing wheels and a support device for a rotary upper machine. There were also two jacks for additional fixing of the tool. The rear part of the main unit served as a bed with a coulter, for which it had a curved shape and increased width. Below, on the rear opener of the bed, a plane was provided, entering the ground and securing the carriage in place. On top there was a toothed rack necessary for horizontal guidance.
The upper carriage of the carriage was made in the form of an elongated plate of high elongation. In its front part, means for installation on the lower machine were provided, as well as racks with mounts for the swinging artillery unit. The rear of the slab passed over the bed of the lower machine and reached the rack. To interact with the latter, there was an appropriate mechanism on the plate. It was proposed to provide the convenience of the calculation with the help of a large platform above the rear bed. When the horizontal guidance angle was changed, the platform moved with the gun. A set of ladders was envisaged for lifting the crew to their places. The upper machine had mounts for mounting a curved armor shield.
Dicke Bertha cannon disassembled and loaded onto regular transport. Photo Kaisersbunker.com
The carriage received a wheel drive of the original design. On two large metal wheels, it was planned to install swinging base plates, which made it possible to increase the size of the supporting surface. When working on an unprepared site, special large box-shaped supports should be substituted under the wheels. They were intended to accommodate the main wheels and install additional jacks.
Other requirements for mobility led to the need to use a new design of the barrel and associated units. The gun received a 420 mm rifled barrel with a length of 12 calibers (over 5 m). Due to the high loads, it was necessary to use a barrel of a complex shape. Its muzzle and front half were in the shape of a truncated cone. The breech and part of the pipe next to it was made in the form of a cylinder with walls of relatively large thickness. On this section of the barrel, fasteners were provided for connecting with a cradle and recoil devices.
Towards a position. Photo Landships.info
The gun received a sliding wedge breech, which moves in a horizontal plane, which is traditional for German artillery. The shutter was equipped with a remote-controlled trigger. Due to the high power of the propellant charge and the corresponding noise, it was allowed to fire a shot only from a safe distance using a special remote control.
The tool cradle was made in the form of a part with a cylindrical inner channel and mounts for two pairs of cylinders on the upper and lower surfaces. Above the barrel and under it were placed recoil devices of the hydraulic type with two recoil brakes and two knurled rollers. A cradle with recoil devices could swing on trunnions mounted on the corresponding supports of the upper machine.
Lower machine and other units before assembly. Photo Kaisersbunker.com
The Dicke Bertha gun received manual guidance mechanisms controlled by several crew numbers. Horizontal guidance within a sector with a width of 20 ° was carried out using the interaction of the opener toothed rack and the mechanism of the upper machine. At the same time, the latter rotated on its axis, changing its position relative to the lower machine. The gear transmission as part of the vertical guidance mechanism made it possible to raise the barrel at angles from + 40 ° to + 75 °.
For use with the new 420-mm mortar, it was decided to develop new shells. Later it was found that such ammunition, subject to certain rules, can also be used by the 42 cm Gamma Mörser howitzer. "Big Bertha" could fire a high-explosive or concrete-piercing shell weighing 810 kg. After the outbreak of the First World War, a 400-kg high-explosive projectile was created. Throwing ammunition was provided by a variable charge placed in a metal sleeve. High-explosive shells of a large mass could leave behind large craters in the ground, as well as cause serious damage to concrete structures. The fragments of the body shattered by the explosion flew to a distance of 1.5-2 km, posing a great danger to manpower.
Installation of the cradle. Photo Kaisersbunker.com
The large mass of the projectile and cartridge case forced the designers to equip the gun with the appropriate equipment. On the left side of the upper machine, a light crane with a manual winch was mounted, with which the crew could lift ammunition to the dispensing line. After training, the gunners could reload the gun in 8 minutes. At the same time, in practice, it took more time to execute a shot, since before firing the crew had to move to a safe distance in order to avoid injury to the hearing organs.
A promising siege mortar in a combat position had a length of about 10-12 m, depending on the position of the barrel. The combat weight was 42.6 tons. When using the maximum propellant charge, the initial speed of the heavy 810-kg projectile reached 330-335 m / s. For a light 400 kg ammunition, this parameter was 500 m / s. A more powerful projectile flew at a distance of up to 9.3 km, a light one - at a distance of 12.25 km.
Installation of the upper machine. Photo Kaisersbunker.com
The large dimensions and mass of the gun, despite all the efforts of the authors of the project, imposed noticeable restrictions on mobility. For this reason, it was proposed to use the wheeled carriage only for transporting the gun over short distances. A different transfer was to be carried out only after disassembly. The design of "Fatty Bertha" provided for the disassembly of a single complex into five separate units, transported separately on their own trailers. In a few hours, the crew could assemble a gun at a firing position, or, conversely, prepare it for departure.
The assembly of the gun began with the unloading of the two main units of the carriage, followed by their connection. At the same time, the transport axle was removed from the lower machine, instead of which the opener was mounted. Then it was proposed to install a cradle on the upper machine, after which the barrel was loaded into it. The assembly was completed with the installation of the platform, shield and other devices. When deployed in position, the wheels of the guns had to be installed on special metal support boxes. The latter had a protruding front plate, against which the front carriage jacks rested. The rear coulter of the carriage plunged into the ground.
Completion of the mortar assembly. Kaisersbunker.com
The order for the construction of the first M-Gerät mortar was received in June 1912. In December of the following year, the concern-developer presented this product for testing. Almost a year earlier, in February 1913, the army ordered the construction of a second gun of a similar type. "Big Bertha" # 2 was manufactured by the beginning of the summer of 1914. By this time, the first prototype had successfully passed part of the tests and was even shown to the country's top leadership. The project received approval, as a result of which the guns could count on mass production and operation in the army.
By the beginning of the First World War, Germany had two Dicke Bertha guns available. In addition, two additional swinging artillery units were made in the form of a barrel and a cradle. In connection with the beginning of the fighting, both ready-made guns were transferred to the army and included in the 3rd battery of short naval guns Kurze Marinekanonen Batterie 3 or KMK 3. Immediately after formation, the unit was sent to Belgium, where German troops tried to take several fortresses. The arrival of two 420-mm mortars and their short combat work made it possible to put an end to several battles. Heavy shells caused serious damage to the fortifications, forcing the enemy to cease resistance.
High-explosive shell and cartridge case. Photo Wikimedia Commons
After the outbreak of World War I, the German command ordered new M-Gerät guns. Until the end of the conflict, the industry managed to build ten full-fledged mortars, as well as produce 18-20 sets of interchangeable barrels and cradles. Serial guns differed from the experienced ones in a number of innovations. So, instead of spliced wheels, products with solid metal rims were proposed. The bolt was improved, and a small additional platform appeared in front of the shield for the placement of gunners. The rest of the serial armament was similar to the experimental one. The serial guns were consolidated into five new batteries.
After Belgium, mortars were sent to France. Subsequently, they were used on all European fronts during various operations. The main objectives of mortars have always been to strengthen the enemy. Over time, as the resource was depleted and problems with ammunition appeared, the artillerymen began to suffer losses. At least two of the Big Bertha guns were destroyed when fired due to the explosion of a shell inside the barrel. After these incidents, the crews of the remaining guns received new orders regarding safety when firing.
Model of the Big Bertha gun: breech and means for loading shells. Photo Landships.info
The large mass of concrete-piercing shells in combination with the speed gained during the fall gave very good results. In some cases, an 810-kg projectile could penetrate up to 10-12 concrete. The use of mortars in Belgium turned out to be especially successful. This country had outdated forts made of concrete without metal reinforcement. Such fortifications were easily destroyed by intensive shelling. A remarkable result of the shooting was obtained during the attack on the Belgian Fort Launsen. The shell broke through the overlap of one of the fortifications and hit the ammunition depot. 350 defenders of the fortress were immediately killed. The fort soon surrendered.
France, unlike Belgium, managed to build a sufficient number of fortifications from more durable reinforced concrete, which made the combat work of the M-Gerät crews noticeably more complicated. Nevertheless, in such cases, the effectiveness of the use of 420-mm projectiles was quite high. Long-term shelling made it possible to inflict significant damage on the enemy's fortress and facilitate its further capture.
The result of the explosion of a projectile in the barrel. Photo Kaisersbunker.com
In 1916, four batteries with eight mortars at once were transferred to the Verdun area to fight the newest French fortifications. The fortresses built according to modern technologies were no longer so easy to succumb to the blows of heavy shells. It was not possible to break the thick, solid floors, which led to corresponding consequences throughout the entire operation. During the Battle of Verdun, German artillerymen for the first time faced a serious problem in the form of enemy aircraft. Enemy pilots identified firing positions and directed counter-battery fire at them. German soldiers had to urgently master the camouflage of large guns.
Siege mortars Dicke Bertha were quite actively used by German troops on all fronts, but the number of such weapons in the troops was constantly decreasing. As the operation progressed, the guns went out of action for one reason or another, primarily due to the bursting of the shell in the barrel. In addition, there is information about the destruction of several guns by the return fire of the French artillery. Due to accidents and retaliatory attacks by the enemy at the time of the end of hostilities, the German army had only two Berts.
One of the last weapons stored in the United States. Photo Landships.info
Soon after the end of the fighting, in November 1918, the victorious countries got the two remaining M-Gerät super-heavy mortars. These products were handed over to American specialists, who soon took them to the Aberdeen Proving Ground for comprehensive testing. American gunners showed great interest in the unique 420-mm gun, but quickly became disillusioned with it. For all its outstanding combat qualities, the German gun had unacceptably low mobility. Even the presence of a wheeled carriage did not allow to quickly transfer it to a new position.
After the completion of the tests, the guns were sent for storage. Later they were restored and included in the museum exposition. Two "Big Berts" remained museum pieces until the forties. In 1942, one gun was decommissioned and disassembled, and in the early fifties the same fate befell the second. On this, all the guns built in Germany ceased to exist.
Modern model of the weapon. Landships.info
The M-Gerät / Dicke Bertha super-heavy siege mortar was a specialized weapon designed for a specific combat mission. During the First World War, such systems performed well in the fight against outdated forts. Newer fortifications with different defenses were no longer an easy target, even for 420 mm guns. Until the end of the war, mortars of special power were used with a certain efficiency in various operations, but the defeat of Germany and the events that followed put an end to the history of an interesting project. Both surviving mortars could now only count on preservation as museum exhibits.
