Stupa front view, with its short-barrel 15cm Sturmhaubitze (StuH) assault howitzer in circular mantle. Howitzer definition referred to guns employed as angled artillery or close proximity direct fire, such as pillbox and building busting operations. Howitzer - en.wikipedia.org/wiki/Howitzer

In Fall 1942 Stalingrad street battles, German Blitzkrieg tactics came to an end as Soviets poured reinforcements into the breech, thus forcing Germans to fight intermingled in urban warfare among each city block or buildings. Blitzkrieg : The Lightning War - en.wikipedia.org/wiki/Blitzkrieg

Common stories were that Germans would take the bottom floors while surviving Soviets defended upper floors until their ammunition ran out. PC First-Person-Shooter game simulating this type city combat is : Call of Duty 2 - www.gamespot.com/pc/action/callofduty2/screenindex.html

To counter these fortified positions, Germans required mobile weapon platform able to demolish entire city blocks from a distance rather than costly frontal infantry assaults. Regular tanks were unsuited since their powerful rifled guns could actually pierce through an entire city block before denotation. Stupa large caliber capacity can delivery high explosive yield in single shot, its short barrel design meant shells were fired at low velocity for localized impact. Urban warfare - en.wikipedia.org/wiki/Urban_warfare

Rollover : Engine deck area, the three spare wheels have slightly different hub cap designs. Parallelogram with upside-down T (lower-left of muffler) was German tactical insignia for assault guns. Muffler's annealed rust-like appearance made from painting Elmers Glue onto plastic part, sprinkle baking soda onto its surface, paint with TESTOR Red Brown, dry-brush with TESTOR Tan. German Vehicle Markings - members.shaw.ca/grossdeutschland/vehicle.htm

Inset : Third self-propelled sIG33 version was field-installation into Panzer III chassis, which had wider fighting compartment and better suspension system. Its full German name should be 15cm sIG33 (Sf) auf Panzerkampfwagen III (15cm heavy infantry howitzer on Panzer III tank), but since this was field modified, no official designation exist. Photo above shows service with German Deutsche Africa Korps (DAK) in North Africa. Afrika Korps - en.wikipedia.org/wiki/DAK