Brummbär The Sturmpanzer ( also known as " Sturmpanzer 43 " or " Sd . Kfz . 166 " ) was a German armoured infantry support gun based on the Panzer IV chassis used in the Second World War . It was used at the Battles of Kursk , Anzio , Normandy , and helped to put down the Warsaw Uprising . It was known by the nickname Brummbär ( German : " Grouch " ) by Allied intelligence , a name which was not used by the Germans . Just over 300 vehicles were built and they were assigned to four independent battalions . Development . The " Sturmpanzer " was a development of the Panzer IV tank designed to provide direct infantry fire support , especially in urban areas . The result was the " Sturmpanzer " , which used a Panzer IV chassis with the upper hull and turret replaced by a new casemate - style armored superstructure housing a new gun , the " Sturmhaubitze " ( StuH ) 43 L / 12 developed by Skoda . It fired the same shells as the 15 cm sIG 33 heavy infantry gun . Thirty - eight rounds , with separate propellant cartridges , could be carried . It used the Sfl . Zf . 1a sight . The combined weight of the shell and cartridge ( for an HE shell and for a propellant cartridge ) made the work of the loader arduous , especially if the gun was elevated to a high angle . An MG 34 machine gun was carried that could be fastened to the open gunner ' s hatch , much like the arrangement on the " Sturmgeschütz " III Ausf . G . Early vehicles carried a MP 40 sub - machine gun inside , which could be fired through firing ports in the side of the superstructure . The driver ' s station projected forward from the casemate ' s sloped frontal armor plate and used the Tiger I ' s " Fahrersehklappe 80 " driver ' s sight . The fighting compartment was ( badly ) ventilated by natural convection , exiting out the rear of the superstructure through two armored covers . Sideskirts were fitted on all vehicles . Early vehicles were too heavy for the chassis , which lead to frequent breakdowns of the suspension and transmission . Efforts were made to ameliorate this from the second series onwards , with some success . In October 1943 it was decided that the StuH 43 gun needed to be redesigned to reduce its weight . A new version , some lighter than the StuH 43 , was built as the StuH 43 / 1 . Some of the weight was saved by reducing the armor on the gun mount itself . This gun was used from the third production series onwards . Zimmerit coating was applied to all vehicles until September 1944 . Production series . First . Production of the first series of 60 vehicles began in April 1943 . Fifty - two of these were built using new Panzer IV Ausf . G chassis and the remaining 8 from rebuilt Ausf . E and F chassis . Survivors , about half , were rebuilt beginning in December 1943 ; they were mostly rebuilt to 2nd series standards . Second . Production restarted in December 1943 of another 60 vehicles , using only new Ausf . H chassis , and continued until March 1944 . The " Sturmpanzer ' s " baptism in combat at the Battle of Kursk proved that the driver ' s compartment was too lightly armored and it was reinforced . The gunner ' s hatch was removed and a ventilator fan was fitted , much to the relief of the crew . Internally sprung , steel - rimmed road wheels replaced the front two rubber - rimmed road wheels in an effort to reduce the stress on the forward suspension that was only partially successful . Third . Production of the 3rd series ran from March to June 1944 with few changes from the second series . The Fahrersehklappe 80 was replaced by periscopes and the lighter StuH 43 / 1 was used . Fourth . The superstructure was redesigned in early 1944 for the fourth series , which used the chassis and HL120TRM112 engine of the Ausf . J , and was in production between June 1944 and March 1945 . It featured a redesigned gun collar , as well as a general reduction in height of the superstructure . This redesign also introduced a ball mount in the front superstructure for a MG 34 machine gun with 600 rounds . The vehicle commander ' s position was modified to use the cupola of the " Sturmgeschütz " III Ausf . G , which could mount a machine gun for anti - aircraft defense . The first unit to take the " Sturmpanzer " into battle was " Sturmpanzer - Abteilung 216 " . It was formed at the end of April 1943 and transferred in early May to Amiens to train on its new assault guns . It was organized into 3 line companies , each with 14 vehicles , and a battalion headquarters with 3 vehicles . It arrived in Central Russia on 10 June 1943 to prepare for " Unternehmen Zitadelle " ( Operation Citadel ) , the German attack on the Kursk salient . For this action it was temporarily assigned as the third battalion of " schweres Panzerjäger Regiment 656 " ( " Heavy Anti - tank Regiment 656 " ) under the command of the 9th Army of Army Group Center . Combat history . It remained in the Orel - Bryansk area until its transfer to the Dnepropetrovsk - Zaporozhe area at the end of August . Its vehicles were refitted there and it remained there until the Zaporozhe Bridgehead was abandoned on 15 October . The battalion retreated to Nikopol where it helped to defend the German salient there until it was withdrawn back to the Reich at the end of December . The Allied landing at Anzio on 22 January 1944 caused the battalion , fully independent once more , to be transferred there in early February with 28 vehicles to participate in the planned counterattack against the Allied beachhead , " Unternehmen Fischfang " . This failed in its objective , but the battalion remained in Italy for the rest of the war . The battalion still had 42 vehicles on hand when the Allies launched their Po Valley offensive in April 1945 , but all were blown up to prevent capture or lost during the retreat before the war ended in May . " Sturmpanzer - Abteilung 217 " was formed on 20 April 1944 at the Grafenwöhr Training Area from cadres provided by " Panzer - Kompanie 40 " and " Panzer - Ersatz Abteilung 18 " , although it did not have any armoured fighting vehicles until 19 ' Sturmpanzer ' s ' were delivered at the end of May It departed 1 / 2 July for the Normandy Front . Here it had to detrain in Condé sur Noireau , some behind the front lines , because the Allies had heavily damaged the French rail network . Many of the battalion ' s vehicles broke down during the road march to the front lines . The first mention of " Sturmpanzer ' s " in combat is on 7 August near Caen . On 19 August , the battalion had 17 " Sturmpanzers " operational and another 14 in maintenance . Most of the battalion was not trapped in the Falaise Pocket and managed to retreat to the northeast . It had only 22 vehicles in October , which were divided between the 1st and 2nd Companies ; the surplus crews were sent to " Panzer - Ersatz Abteilung 18 " . It participated in the Battle of the Bulge , only advancing as far as St . Vith . It was continually on the retreat for the rest of the war and was captured in the Ruhr Pocket in April 1945 . " Sturmpanzer - Kompanie z . b . V . 218 " was raised in August 1944 . It was sent to Warsaw where it was attached to " Panzer Abteilung ( Fkl ) 302 " . It remained on the Eastern Front after the Warsaw Uprising was suppressed and was eventually wiped out in East Prussia in April 1945 . It was supposed to have been the cadre for " Sturmpanzer Abteilung 218 " in January 1945 , but it was never pulled out of the front lines to do so . " Sturmpanzer - Kompanie z . b . V . 2 . / 218 " was raised simultaneously with " Sturmpanzer Kompanie z . b . V . 218 " , but was transferred to the Paris area on 20 August . Nothing is known of its service in France , but company personnel were sent to " Panzer - Ersatz Abteilung 18 " at the end of the year and were supposed to have been used in the formation of " Sturmpanzer Abteilung 218 " . " Sturmpanzer - Abteilung 218 " was ordered formed on 6 January 1945 with three companies with a total of 45 " Sturmpanzer ' s " , but it received " Sturmgeschütz " III assault guns during February instead . " Sturmpanzer - Abteilung 219 " was originally to be formed from " Sturmgeschütz - Brigade 914 " , but this was changed to " Sturmgeschütz - Brigade 237 " in September 1944 . In mid - September 1944 the brigade transferred to the Döllersheim Training Area to reorganize and re - equip . Only ten Sturmpanzer ' s had been received when the battalion was alerted on 15 October to participate in ' Unternehmen Eisenfaust ' , the German coup to forestall Hungary ' s attempt to surrender to the Allies . All the vehicles were given to the " First Company " and it departed for Budapest on the following day . Bomb damage to the rails delayed its arrival until 19 October , by which time it was no longer needed as a pro - German government had been installed . It was railed to St . Martin , Slovakia for more training . The battalion was transferred to the vicinity of Stuhlweißenburg to relieve trapped German forces in Budapest . It remained in the vicinity of Budapest until forced to retreat by advancing Soviet forces . Surviving vehicles . Four Sturmpanzers survive :