Karl-Gerät (040/041) ( in German), also known as Mörser Karl, was a World War II German self-propelled siege mortar (Mörser) designed and built by Rheinmetall. Its heaviest munition was a diameter, shell; the range for its lightest shell of was just over . Each gun had to be accompanied by a crane, a two-piece heavy transport set of railcars, and several modified tanks to carry shells.
Seven guns were built, six of which saw combat between 1941 and 1945. It was used in attacking the Soviet fortresses of Brest-Litovsk and Sevastopol, bombarded Polish resistance fighters in the Warsaw Uprising, participated in the Battle of the Bulge, and was used to try to destroy the Ludendorff Bridge during the Battle of Remagen. One Karl-Gerät has survived; the remainder were scrapped after the war.
Development In March 1936 Rheinmetall made a proposal for a super-heavy howitzer to attack the Maginot Line. Their initial concept was for a weapon that would be transported by several tracked vehicles and assembled on site, but the lengthy preparation time drove them to change it to a self-propelled weapon in January 1937. Extensive driving trials took place in 1938 and 1939 using the first Neubaufahrzeug tank prototype and a scale model to investigate the extremely high ground pressure and steering of such an enormous vehicle. Firing trials took place in June 1939.Jentz, pp. 4–8 The full-scale driving trials were held at Unterlüss in May 1940. General Karl Becker of the Artillery was involved in the development, from whom the huge weapon gained its nickname.Jentz, p. 1
In total, seven Karl-Gerät howitzers were manufactured. The first six had the nicknames "Adam" (later "Baldur"), "Eva" (later "Wotan"), "Thor", "Odin", "Loki", and "Ziu"; the seventh, the research and test weapon (Versuchs-Gerät), had no name. Delivery of the six production vehicles took place from November 1940 to August 1941.Jentz, p. 17
In February 1941, discussions commenced concerning increasing the range of the weapon, and in May 1942, Gerät 041 barrels were ordered for the six vehicles. At a conference with Adolf Hitler in March 1943 it was stated that the first Gerät 041 would be delivered by June 1943, and the third by mid-August. Only three of the Gerät 041 barrels were actually completed for mounting on Karl-Gerät Nr. I, IV and V,Jentz, p. 49 although any vehicle could be converted to use the smaller weapon.
Twenty-two Panzer IV Ausf. D, E and F chassis were modified, with a superstructure capable of carrying four shells that replaced the turret, and outfitted with a crane as Munitionsschlepper für Karl-Gerät ammunition transporters/loaders.Chamberlain & Doyle, p. 262 Two or three of these Munitionsschlepper were assigned to each weapon.
Variants Gerät 040: original model, with a shorter (L/7) calibre barrel Gerät 041: later model, with a long (L/11.55) calibre barrel.
Description
The 124-ton vehicle was propelled by a Daimler-Benz MB 503A 12-cylinder liquid-cooled gasoline engine or a Daimler-Benz MB 507C 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 . For longer distances the Karl-Gerät was disassembled using a special mobile crane into seven loads. The chassis was loaded onto a six-axle Culemeyer-Strassenroller lowboy trailer. The other parts of the gun were lighter and used four-axle trailers. If the trailer with the chassis on board had to cross a bridge that couldn't carry their combined weight the chassis had to be off-loaded and driven across under its own power.Jentz, pp. 8, 14–16
Long-range transport and preparation procedures The weapon was moved long 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-axle bogies.Jentz, p. 8 When it reached its destination, the weapon was detached from railcars' supporting arms and driven to its intended firing location. The chassis of the ordnance was then lowered to the ground by "raising" the continuous track units' roadwheels by rotating their torsion-bar-sprung suspension arms to drop the chassis close to the ground to distribute the recoil forces more evenly in preparation for firing - the roadwheels for each trackset were also similarly "raised" to allow the tracks to clear the rails while being transported by rail, between the pair of Schnabel railcars. 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, but the land to be used for the ordnance's firing position had to be precisely leveled and the approach route prepared ahead of time to fill in soft spots and any ditches, etc.Jentz, p. 19 The mortar could only be loaded at zero elevation, so it had to be re-aimed between shots.Jentz, p. 8
Automotive features The various Karl-Geräte used two different types of transmissions, engines and suspension system in a bewildering set of combinations. The table below outlines how each vehicle was outfitted. After May 1944 the gasoline engines were replaced by diesels. Little information is available for No. VII, the experimental model, and the data below must be regarded as unconfirmed.Jentz, p. 17
No. I II III IV V VI VII NicknameAdam/BaldurEva/WotanThorOdinLokiZiuNone Ausf.1233456 EngineMB 503 AMB 503 AMB 507 CMB 507 CMB 507 CMB 503 AMB 503 A Transmission3-speed Ardelt3-speed Voith Turbo4-speed Ardelt4-speed Ardelt3-speed Voith Turbo3-speed Voith Turbo4-speed Ardelt Speed10 km/h10 km/h6 km/h6 km/h6 km/h6 km/h6 km/h Range (km)42426060604242 Roadwheels(number per side/rim type)8 rubber8 rubber11 steel11 steel11 steel11 steel11 steel Return rollers8 rubber8 rubber6 rubber6 rubber6 rubber6 rubber6 rubber Torsion bars (mm)2600260021152115211521152115 Track pitch (mm)170170250240240240240 Link per side1331339494949494 Sprocket teeth17171212121212
Ammunition
The original heavy concrete-piercing shells (schwere Betongranate) made a crater up to wide and deep.Jentz, p. 37 More range was desired and the light concrete-piercing shell (leichte Betongranate) 040 was introduced in 1942. Firing trials for the shells were not completed until the end of 1944 and they were not used in combat before then. The original 600 mm heavy shell had no designation other than the name. The Gerät number was added for the newer shells.Jentz, pp. 24-5 ShellCaliber mm (in)Weight kg (lb)Weight of explosive fill kg (lb)Muzzle velocity m/s (ft/s)Max range m (yd)Penetration m (ft) heavy concrete-piercing shell (schwere Betongranate) + of concrete light concrete-piercing shell (leichte Betongranate) 040 + of concrete light concrete-piercing shell (leichte Betongranate) 041no data of concrete high-explosive shell (Sprenggranate) 041no datano datano datano datano data
Combat history 1941 On 3 January 1941 Heavy Battery (schwere 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 Heavy Artillery Battalion (schwere Artillerie Bataillon) 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 howitzers, 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 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 the 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.Jentz, p. 33
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. Second 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 24 June. It was ordered home that day by Army Group Center where the battalion was ordered to reform with eight Mörser 18 howitzers on 6 August 1941.Jentz, pp. 34–37
1942 In preparation for the attack on Sevastopol scheduled for the early summer Heavy Artillery Battalion 833 was ordered to form a Karl-Batterie with three weapons on 18 February 1942, two of which were "Thor" and "Odin". Camouflaged firing positions long, wide and deep had to be dug for each howitzer to minimize Soviet counter-fire before they could move into position. On 20 May 1942 the 11th Army reported all three Karl-Geräte were at the front with a total of 72 heavy and 50 light concrete-piercing shells. LIV Army Corps reported that 19 heavy shells were fired between 2 and 6 June, 54 on 7 June and all 50 light shells between 8 and 13 June. More shells (29 heavy and 50 light) were 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 twin-gun armored turrets of the Maxim Gorkii coastal defense battery,The history of Maxim Gorki-I Naval Battery, Sevastopol, retrieved on 13 January 2009 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 away (called the Bastion by the Germans). On 19 July 1942 the battery was ordered to ship their weapons to Hillersleben for refurbishment. One dud shell was recovered by the Soviets and flown to Moscow for evaluation.Jentz, pp. 40–43
On 7 July 1942 Heavy Artillery Battalion 833 was ordered to form another battery with one or two Karl-Geräte. 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 Heavy Artillery Battalion 833. On 22 July the Army High Command (Oberkommando des Heeres (OKH)) issued an order to send the battery to Army Group North to support its planned offensive, Operation George (Unternehmen Georg), against Leningrad. The order for Georg, dated 22 August, specified Battery 628 with three guns, presumably with two operational guns and one in reserve was to participate. Army Group North reported the battery's arrival on 1 and 2 September 1942, but the Soviets preempted Georg with heavy attacks against the German forces besieging Leningrad so the Karl-Geräte didn't get into action.Jentz, p. 43
On 18 October OKH ordered the 11th Army to transfer the battery as soon as possible to Leipzig, but the 11th Army asked to retain it to use in a new version of Georg to begin later that month. Georg was again postponed in late October, and later canceled. A new attack, code-named Feuerzauber (Fire Magic), was planned in which the battery was to participate, but it too was canceled after the Soviet encirclement of the German forces attacking Stalingrad. OKH finally recalled the battery on 4 December 1942 when it was clear that it had no mission.Jentz, p. 43
1943