Mörser Karl-Gerät was a World War II German self-propelled siege mortar designed and built by Rheinmetall. It was meant to be behind front lines by a couple miles and expel huge shells to bunkers and buildings to get the enemy out. The Karl-Gerät was a very accurate vehicle, accurate enough from 6 miles to destroy a small bunker.
Seven guns were built (nicknamed Adam or Baldur, Eva or Wotan, Thor, Odin, Loki, and Ziu, the prototype had not nickname), six of which saw combat between 1941 and 1945. There were 2 variants: 040 and 041. Gerät 040: original model, armed with a short 60 centimetres (24 in) calibre barrel; and Gerät 041: later model, armed with a long (L/11.55) 54 centimetres (21 in) calibre barrel.
The original heavy 60 cm concrete-piercing shells made a crater up to 15 m (49 ft) wide and 5 m (16 ft) deep, with a maximum range of 4,320 m (4,720 yd). More range was desired, about 6,440 m (7,040 yd), and the light concrete-piercing shell 040 was introduced in 1942. Firing trials for the 54 cm shells were not completed until the end of 1944 and they were not used in combat before then, being its maximum range of 10,060 m (11,000 yd).
The 124-ton vehicle was accompanied by a crane, a heavy transport trailer, and several modified tanks to carry shells. To rail transport, the Mörser's long distance special railcars were made that suspended the Mörser between them while being transported. To road transport, the Mörsers could be partially disassembled and transported by specially created trailers.
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. Two or three of these Munitionsschlepper were assigned to each weapon.
It was designed to break the Magjnot Line. Although work started in 1936, it was not ready by the fall of France. Nevertheless, plenty of targets in Russia were waiting for it. It was used in attacking the Soviet fortresses of Brest-Litovsk and Sevastopol. Later bombarded Polish resistance fighters in Warsaw, participated in the Battle of the Bulge, and was used to try to destroy the Ludendorff Bridge during the Battle of Remagen.
In this episode World of Tanks will tell you how the mortar got the name "Karl," what its main purpose in battle was, and what part it played during World War II.