▁idea ▁for ▁a ▁heavy ▁inf antry ▁support ▁vehicle ▁capable ▁of ▁demol ishing ▁heavily ▁def ended ▁buildings ▁or ▁fort ified ▁areas ▁with ▁a ▁single ▁shot ▁came ▁out ▁of ▁the ▁experiences ▁of ▁the ▁heavy ▁urban ▁fighting ▁in ▁the ▁Battle ▁of ▁St aling rad ▁in ▁ 1 9 4 2 . ▁At ▁the ▁time , ▁the ▁We hr macht ▁had ▁only ▁the ▁St urm - In fan ter ieg esch üt z ▁ 3 3 B ▁available ▁for ▁destroy ing ▁buildings , ▁a ▁St urm gesch üt z ▁III ▁variant ▁armed ▁with ▁a ▁ 1 5 ▁cm ▁s IG ▁ 3 3 ▁heavy ▁inf antry ▁gun . ▁Tw elve ▁of ▁them ▁were ▁lost ▁in ▁the ▁fighting ▁at ▁St aling rad . ▁Its ▁successor , ▁the ▁St ur mp an zer ▁IV , ▁also ▁known ▁by ▁Al lies ▁as ▁Br um mb är , ▁was ▁in ▁production ▁from ▁early ▁ 1 9 4 3 . ▁This ▁was ▁essentially ▁an ▁improved ▁version ▁of ▁the ▁earlier ▁design , ▁mount ing ▁the ▁same ▁gun ▁on ▁the ▁Pan zer ▁IV ▁ch ass is ▁with ▁greatly ▁improved ▁arm our ▁protection . ▁ ▁While ▁greatly ▁improved ▁compared ▁to ▁the ▁earlier ▁models , ▁by ▁this ▁time ▁inf antry ▁anti - t ank ▁weapons ▁were ▁impro ving ▁dram atically , ▁and ▁the ▁We hr macht ▁still ▁saw ▁a ▁need ▁for ▁a ▁similar , ▁but ▁more ▁heavily ▁arm oured ▁and ▁armed ▁vehicle . ▁Therefore , ▁a ▁decision ▁was ▁made ▁to ▁create ▁a ▁new ▁vehicle ▁based ▁on ▁the ▁T iger ▁tank ▁and ▁arm ▁it ▁with ▁a ▁