The StuG IV (or Sturmgeschutz IV, SdKfz 167) was a newer approach to the successful StuG III tank destroyer / assault gun line. The type saw extensive combat actions throughout World War 2, primarily with German infantry divisions. The new vehicle was built atop the chassis of the Panzer IV Medium Tank and featured the powerful 7.5cm (75mm) StuK 40 L/48 gun set within the fixed hull superstructure, retaining the exceptionally low profile of its predecessor. It was fielded beginning in December of 1943 after Hitler's personal approval of the program and would see production running up until the final weeks of the war in 1945.
Among the features that distinguished the new "StuG" design from the preceding StuG III was the aforementioned use of the Panzer IV Medium Tank hull (albeit sans the turret emplacment). As a turretless design in which the gun, recoil system and breech were all set within the hull superstructure itself, the StuG IV could be produced more quickly in greater numbers. However, this was at the expense of tactical flexibility which forced the crew to aim the entire tank in the direction of the enemy (as opposed to rotating solely the turret). The vehicle was given six smoke grenade dischargers for basic screening and self-defense. Additionally, the crew could call upon one or two 7.92mm MG34 General Purpose Machine Gun(s) to counter enemy infantry (one was fitted with a collapsing armored shield). Side skirt armor was made standard to counter attacks from anti-tank weapons along the vulnerable flanks. Frontal armor was increased for the better and Zimmerit paste coating was applied on surfaces for protection against "sticky" bombs (grenades, mines or homemade explosives attached to the tank by enemy infantry). A Maybach HL 120 V-12 series water-cooled gasoline engine of 300 horsepower powered the vehicle up to speeds of 25 miles per hour. Operational range was 130 miles.
For the 75mm gun, the distinctive "pig's mantlet" armored shield was affixed to the where the barrel entered the hull superstructure. This offered increased point protection at a vulnerable area where the thick angled surface of the mantlet could be called upon to deflect or absorb enemy projectiles or shell splinters. The vehicle carried a supply of up to 63 x 75mm projectiles which proved greater that that on the previous StuG III offering.
The vehicle was operated by four personnel including the driver, vehicle commander, gunner and ammunition handler. The driver was seated at the front-left of the vehicle with the remaining crew in the main portion of the hull.
Production of StuG IV series assault guns was undertaken by Krupp of Germany from 1943 to 1945. 1,139 of the vehicles were eventually delivered (compared to the 9,000 or so StuG IIIs produced prior). As assault guns, the type could be called upon to serve in an offensive or defensive role depending on the current state of the battle - engaging enemy formations or enemy armor with equal lethality. The German 75mm main gun certainly proved its penetrating excellence at range against most Allied armored vehicles of the war save for a few Soviet-originated heavy-weights. Naturally, captured StuG IV vehicles in working condition were reconstituted by the Soviets along the Eastern Front in their brutal fight with the Germans. As their numbers restricted their availability, the StuG IV did not outright replace the capable StuG III vehicles but were instead used in conjunction when possible.
Very few StuG IV vehicles remain for display today (2013).