60 cm Morser L / 8.45 cal. 600 mm or 54 cm Morser L / 13 cal. 540 mm and its improved version 60-cm Karl Gerat 041 is the heaviest self-propelled siege mortar used during World War II. It was part of the armament of the German army. Work on this powerful weapon began at the Rheinmetall concern in 1936, and the first example of this weapon entered service with the Wehrmacht in 1940. During the entire war, one prototype was created and six copies were used by the army with proper names: Baldur, Wotan, Thor, Odin, Loki and Ziu. Karl mortars were used in a marginal way during World War II.