In March 1943, Krupp proposed the construction of a heavy assault mortar. In May, they presented a design called Bär (bear). The Bär mounted a 305 mm gun, capable of firing high-explosive and concrete-piercing ammunition, and used elements from the Panther and Tiger I.
On 27 May 1943, Alkett presented a design which mounted a 380 mm mortar on a Tiger I chassis. On this design, the superstructure was mounted at the rear, as on the Ferdinand. It was decided to pursue Alkett's design, rather than Krupp's.
The rear-mounted superstructure, which would have required that the engine be moved to the front of the vehicle, was quickly abandoned. The simpler design of the Panzersturmmörser (armored assault mortar) was presented on 20 October 1943. The original intention was the build Tiger I chassis specifically for the Panzersturmmörser. Due to delays, however, it was decided to use existing Tiger I chassis sent back from the front for field repairs.
A modified 380 mm anti-submarine rocket launcher, the 38 cm Raketenwerfer 61 L/5,4, was used for the Panzersturmmörser. It fired a fin-stabilized 345 kg rocket at a speed of 300 m/s.
The first three vehicles were not completed until August 1944, with a further ten built in September 1944, and the final five in December 1944.
The Panzersturmmörsers were organized in special Sturm-Mörser-Kompanien (assault mortar companies). The first unit, Sturm-Mörser-Kompanie 1000, was sendt to Warsaw with two Panzersturmmörsers during the Warsaw uprising. Two more units, Sturm-Mörser-Kompanie 1001 and 1002, were created, with an authorized strength of four Panzersturmmörsers each. Sturm-Mörser-Kompanie 1000 and 1001 fought against the Western Allies in the Ardennes in December 1944.
There is anecdotal evidence of Panzersturmmörsers fighting Allied tanks. One story reports how three Medium Tank, M4's were destroyed by a single rocket. In another instance, a former US soldier recalls how a Panzersturmmörser destroyed Medium Tank, M4's, leaving holes in the ground the size of the vehicle itself. While the Panzersturmmörser was certainly well-armored, it was however in no way suited for fighting tanks, given its excessive weight and slow loading time.
|Panzer-Ersatz-Abteilung 500||1||-||-||Cast iron|
|Sturm-Mörser-Kompanie 1000||1||-||-||Fgst. 250 091|
|1||-||-||Fgst. 250 230|
|2||26 October 1944||1 December 1944||
|Sturm-Mörser-Kompanie 1001||4||-||11 October 1944||
|Sturm-Mörser-Kompanie 1002||2||8 December 1944||11 December 1944||Fgst. 250 237|
|2||13 December 1944||13 December 1944||
|Sturm-Mörser-Kompanie 1000||30 December 1944||4||0|
|15 February 1945||3||1|
|Sturm-Mörser-Kompanie 1001||30 December 1944||4||0|
|15 February 1945||4||0|
|Ersatzheer||1 March 1945||0||0|
|Firing height||2.00 m|
|Ground clearance||0.47 m|
|Ground pressure||1.24 kg/cm²|
|Hull, front||100-150 mm|
|Hull, sides and rear||60-80 mm|
|Hull, top||25-40 mm|
|Hull, bottom||25 mm|
|Maximum speed||37.5 km/h|
|Road speed||30 km/h|
|Cross-country speed||20-25 km/h|
|Trench crossing||2.30 m|
|Vertical obstacle||79 cm|
|Fording depth||170 cm|
|Fuel capacity||540 l|
|Mileage (road)||4.50 l/km|
|Mileage (cross-country)||6.35 l/km|
|Cruising range||120 km|
|Cross-country range||85 km|
|Make and model||Maybach HL 230 P 45|
|Displacement||23 000 cc|
|Max. governed speed||2500 rpm|
|Main weapon||38 cm Stu M|
|Auxillary weapon||9 mm MP (2)|
- Pz Kpfw Tiger Ausf. E
- Information about the Panzerkampfwagen Tiger Ausf. E.
- Information abuot the Sturmpanzer.
- BÜHLER & SÖRENSEN. Unterlüss Report No. 295 Part XI : Raketen-Abschußgeräte. Unterlüss : Work Center Unterlüss, 1948. p. .
- Generalinspekteur der Panzertruppen. Zeweusung von Panzern an die Panzerverbände November 1944 - April 1945. Berlin : Oberkommando des Heeres, 1945. p. .
- Generalinspekteur der Panzertruppen. Gep.Kfz.Lage. Berlin : Oberkommando des Heeres, 1945. p. .
- Generalinspekteur der Panzertruppen. Panzerlage vom 1.2.45. Berlin : Oberkommando des Heeres, 1945. 11 p. .
- Generalinspekteur der Panzertruppen. Panzer-Bestand im Ersatzheer : Stand: 1.3.1945. Berlin : Oberkommando des Heeres, 1945. p. .
- JENTZ, Thomas L. & DOYLE, Hilary L. Panzer Tracts No. 20-1 - Paper Panzers : Panzerkampfwagen, Sturmgeschuetz, and Jagdpanzer. Boyds, MD : Panzer Tracts, 2001. 60 p. ISBN 0-9708407-3-X.
- JENTZ, Thomas L. & DOYLE, Hilary Louis. Panzer Tracts No. 8 - Sturmgeschuetz : s.Pak to Sturmmoerser. Darlington, MD : Darlington Productions, 1999. 60 p. ISBN 1-892448-04-X.
- PAWLAS, Karl R. Waffen-Revue W 127 - Datenblätter für Heeres-Waffen, -Fahrzeuge und Gerät. Nurnberg : Publizistisches Archiv für Militär- und Waffenwessen, 1976. 248 p. ISBN 3-88088-213-4.