GD Logo small.gif (6909 bytes) Self Propelled Artillery - Mörser Karl

Historical Information for Mörser Karl

The Karl-Gerät siege guns were built byRheinmetal during the Second World War. In March 1936 Rheinmetall made a proposal for a super-heavy howitzer to attack the Maginot Line. The initial concept was for a weapon that would be transported by several tracked vehicles and assembled on site, but the lengthy preparation time drove Rheinmetall to change it to a self-propelled weapon in January 1937. Extensive driving trials took place in 1938 and 1939 using the Neubau Fahrzeug No. 1 and a scale model to investigate the extremely high ground pressure and steering such an enormous vehicle. The full-scale driving trials were held at Unterluss in May 1940. Firing trials took place in June 1939. Delivery of the six production vehicles took place from November 1940 to August 1941. General Karl Becker of the Artillery was involved in the development, (explaining where the huge weapon gained its nickname).

The 124 ton vehicle was propelled by a Daimler-Benz MB 503 A 12-cylinder liquid-cooled gasoline engine or a MB 507 C 12 cylinder liquid-cooled diesel engine, but this was mainly used for aiming (the mount had only 4 degrees of traverse on each side) as the engines provided a top speed of only 6.2 miles per hour (10 km/h) with massive fuel consumption. The weapon was moved longer distances via rail on a variant of a Schnabel car; the whole chassis was hung between two huge pedestal-mounted swiveling arms fixed to five-bogy railway flatbed cars. When it reached its destination, the weapon was detached from its supporting arms, driven to its intended firing location, then the chassis was lowered to the ground to distribute the recoil forces more evenly in preparation for firing. The Karl-Gerät proved to have no problems moving over normal soil, but under no circumstances was it allowed to make turns on soft soil lest it throw a track. The chassis had to be backed into position to fire, which expedited movement to a new position and the firing position had to be precisely leveled and the approach route prepared ahead of time to fill in soft spots and any ditches, etc. The Mörser could only be loaded at zero elevation, so it had to be re-aimed between every shot.

In total, seven Karl-class guns were manufactured. The first six had the nicknames Adam, Eva, Thor, Odin, Loki, and Ziu; the seventh, the research and test weapon, had no name. In February 1941, discussions commenced concerning increasing the range of the weapon, and in May 1942, 54 cm barrels (Gerät 041) were ordered for the six vehicles. At a conference with Hitler in March 1943 it was stated that the first 54 cm Gerät 041 would be delivered by June 1943, and the third, by mid-August. Only three of the 54 cm barrels were completed and they could be mounted on Nos. I, IV and V, although any model could be converted to use the smaller weapon. Thirteen tracked vehicles were outfitted with special cranes as 'Munitionsträger' ammunition transporters/loaders. These were converted from standard Panzer IV Ausf. D, E and F chassis and modified with a superstructure capable of carrying four shells that replaced the turret. Two of these 'Munitionsträger' were assigned to each weapon with one spare.


On 3 January 1941 Batterie 833 was created at the Bergen training ground and ordered to be combat ready by 15 February 1941. On 2 April 1941 it was expanded into schwere-Artillerie Batallion (Heavy Artillery Battalion) 833. The original Batterie 833 was redesignated as the first battery of the new battalion and a new second battery was formed, each battery having two Mörsers, with orders to be combat ready by 1 May 1941 in preparation for Operation Barbarossa. Initially a single battery was to be deployed against the Soviet fortress at Brest-Litovsk, but that was changed by 14 May 1941 when the other battery was to ordered to attack the Soviet border fortifications near Lviv. The First Battery was assigned to IV Army Corps of 17th Army of Army Group South near Lviv while Second Battery was ordered to support the attack by the 4th Army of Army Group Center against the Brest Fortress. The batteries were issued 60 and 36 rounds respectively..

Little is known of First Battery's operations except that IV Army Corps reported on 23 June that the battery was no longer needed and was no longer operational due to technical deficiencies. 2nd Battery's weapons had some assembly problems, issues with the electrical firing mechanism and non-standard ammunition, not surprising for the Karl-Gerät's combat debut, but managed to fire 31 of their 36 rounds by the 24th of June. It was ordered home that day by Army Group Center where the battalion was ordered to reform with eight 21 cm Mörser 18 howitzers on 6 August 1941.

In preparation for the attack on Sevastopol scheduled for the early summer schwere Artillerie-Abteilung 833 was ordered to form a Karl-Batterie with three Mörsers on 18 February 1942. Camouflaged firing positions 15 metres (49 ft) long, 10 metres (33 ft) wide and 3 metres (9.8 ft) deep had to be dug for each howitzer to minimize Soviet counter-fire before they could move into position. On 20 May 1942 11th Army reported all three Karls were at the front with a total of 72 s. Betongranate (anti-concrete shells) and 50 le. Betongranate. LIV Army Corps reported that 19 s. Betongranate were fired between 2 and 6 June, 54 on 7 June and all 50 light shells between 8 and 13 June. More shells (29 schwere and 50 leichte) shipped to the battery before the end of the month. All 50 light shells were fired on 30 June and 25 heavy shells the following day. Many of these shells were fired at the two 305 millimetres (12.0 in) twin-gun armored turrets of the Maxim Gorkii coast defense battery, although shells fired at the turrets had little effect other than to jam one of the turrets and possibly knock out electrical power to the turrets, both of which were repaired without too much trouble. They did rather more damage to the concrete structure supporting the turrets as well as the command center located some 600 meters away (called the Bastion by the Germans). On 19 July 1942 the battery was ordered to ship their weapons to Hillersleben for refurbishment.

On 7 July 1942 schwere Artillerie-Abteilung 833 was ordered to form a new battery with one or two Karl-Gerät. This was done by 15 August as schwere Batterie 628 (Karl) with two weapons, although sufficient personnel to man three guns was to be furnished by schwere Artillerie-Abteilung 833. On 22 July OKH issued an order to send the batterie to Army Group North to support its planned offensive, Operation George, against Leningrad. The order for Operation George, dated 22 August, specified Batterie 628 with three guns, presumably with two operational guns and one in reserve. Army Group North reported the batterie's arrival on 1 and 2 September 1942, but the Soviets preempted George with heavy attacks against the German forces besieging Leningrad so the Karl-Geräte didn't get into action.

On 18 October OKH ordered the 11th Army to transfer the batterie as soon as possible to Leipzig, but the 11th Army asked to retain it to use in a new version of George to begin later that month. George was again postponed in late October, and later canceled. A new attack, code-named Feuerzauber (Fire Magic), was planned in which the batterie was to participate, but it, too, was canceled after the Soviet encirclement of the German forces attacking Stalingrad. OKH finally ordered the transfer of the batterie on 4 December 1942 when it was clear that it had no mission.

OKH issued orders to create a schwere Artillerie-Abteilung (Karl) on 4 May 1943 using the vehicles and equipment of schwere Artillerie Batterie 628. This became the first battery of the new battalion while the other battery was raised from scratch on 15 May as was the battalion Stab (Headquarters). Each battery had two Karl-Geräte plus a fifth in reserve. 18th Army of Army Group North had plans to use one Karl-Gerät against the Oranienbaum Bridgehead west of Leningrad during the summer of '43, but the battalion was ordered to return the Karl-Geräte to Leipzig on 8 August. Just like the 833rd the battalion was ordered to reform with eight 21 cm Mörser 18 howitzers on 29 August 1943 with effect by 10 September. A Kommando für Karl-Geräte was formed on that same date as caretakers for the weapons. This was redesignated Kommando für Sonder-Gerät des schwere Artillerie-Abteilung (mot.) 628 (Unit for Special-Equipment of heavy Artillery Battalion (motorized) 628) on 2 June 1944.

On 13 August 1944 a battery was ordered to be created immediately with one 54 cm Karl-Gerät and sent to the 9th Army to help it suppress the Warsaw Uprising. The next day the Kommando für Sonder-Gerät formed the Heeres Artillerie Batterie (bodenständige) 638 (Army Heavy Artillery Battery (Static)) with 60 cm Karl-Gerät Nr. VI since no 54 cm was available and a firing table hadn't yet been computed. It arrived at the Warsaw West train station at 0700 on 17 August 1944, although the ammunition train didn't arrive until the following morning.

On 24 August OKH noted that it had been very successful in combat and ordered another Karl-Gerät sent to Warsaw. A second battery, numbered 428, was formed 2 days later by the Kommando für Sonder-Gerät, but it didn't arrive at the Warsaw West train station until 1257 on 7 September 1944. A third Karl-Gerät 040 was shipped to Warsaw on 10 September and incorporated into H.Art.Bttr. (bo.) 428. Karl-Gerät Nr. VI needed repairs and was shipped on 22 September back to Juterbog. At some point a fourth Karl-Gerät was shipped to Warsaw as it was reported as operational on 25 September.

Three days later H.Art.Bttr. 638 was ordered to transfer to Budapest and was loaded without any Karl-Gerät. Nr. V was rerouted to Budapest to equip the battery. H.Art.Bttr. 428 followed on 10-11 October 1944. Both batteries were ordered back to Warsaw on 19 October, although they didn't arrive until 28 October. On 6 November H.Art.Bttr. 638 transferred one Karl-Geräte 040 to H.Art.Bttr. 428 and returned to Jüterbog on 10 November to rearm with a Geräte 041. H.Art.Bttr. 428 didn't remain near Warsaw much longer and departed for Jüterbog itself on 15 November.

In 1945, "No. II (Eva)" as well as "No. V (Loki)" were captured by US forces in the period 21 March to 11 April 1945. No. VI was captured by the Red Army, probably at Jutobog on 20 April 1945. This is on display at Kubinka, although marked as No. I (Adam). No. IV was captured by the Red Army. No. VII (experimental chassis) was captured by the US Army in Hillersleben and later shipped to Aberdeen Proving Grounds but later scrapped.

The fate of guns No.I and No.III are not known. It is probable both were captured by the Red Army in Jüterbog.

Technical Information Moser karl

Production history







Number built



Gerät 041



124,000 kilograms (122 LT; 137 ST) (firing)


11.15 metres (36.6 ft)

Barrel length

420 centimetres (170 in) L/7


3.16 metres (10.4 ft)


4.38 metres (14.4 ft) (firing)


21 (Gun Commander, Driver, Assistant Driver, 18 x Gunners)


separate loading, cased charges


60 centimetres (24 in)


horizontal sliding wedge




55° to 70°


Rate of fire

1 round/10 min

Muzzle velocity

220 m/sec (s. Betongranate)

Effective range

4,320 metres (2.68 mi)


Gerät 040


Daimler-Benz MB 503 A gasoline or Daimler-Benz MB 507 C diesel 580 hp




42 kilometres (26 mi) (gasoline engine)
60 kilometres (37 mi) (diesel engine)


6 km/h (3.72 mph) to 10 km/h (6.2 mph)