With the growth and evolution of the German panzer force, it was realized that there is a need for dedicated and mobile anti-tank weapons to be a part of new armoured formations. As early as March of 1940, Germans produced first self-propelled anti-tank gun mounted on tank chassis – Panzerjager I armed with ex-Czechoslovak 47 mm Pak(t) 36 gun that used PzKpfw I Ausf B tank chassis.
The vehicle was followed by Marder I vehicles that used captured French tank chassis, Marder II that used various PzKpfw II chassis and Marder III that used ex-Czechoslovak PzKpfw 38(t) chassis. All Marders were armed with German made 75 mm Pak 40 or captured Soviet 76.2 mm Pak 36(r) guns and offered minimal protection for their crews. All those vehicles were created in order to increase the mobility of anti-tank weapons by mounting them on variety of available and often obsolete tank chassis. They were the first generation of tank destroyers/tank hunters and were all seen as ..interim solution” implemented to fill the gaps until better designs can be introduced into service.
The real need was for a dedicated and purpose build tank destroyer/tank hunter that could carry large calibre anti-tank weapon and offer full protection for the crew. The concept was to utilize existing tank chassis and mount it with a low superstructure that would house the main armament, ammunition and crew. Lack of turret would allow this vehicle to carry large calibre gun that could not be normally mounted in the turret. Early Sturmgeschutz III followed that concept and proved to be a successful tank destroyer, while being originally designed as an infantry support vehicle. In March of 1942, Stug III Ausf F, armed with 75 mm L/43 and later with L/48 gun, entered production. It was not only an assault gun but also a badly needed first purpose build tank destroyer. It was followed by Ausf F/8 and finally by Ausf G. All three models proved to be very successful tank destroyers and remained in service to the last days of war. In December of 1942, new tank destroyer with 100 mm frontal armour, armed with 75 mm Pak 42 L/70 gun (variant of the gun that was used to arm the Panther) and based on PzKpfw IV was requested by the Waffenamt. The vehicle was to have low silhouette with main gun mounted in a superstructure. It was to be the first vehicle of the second generation of tank destroyers / tank hunters.
Jagdpanzer IV was an improved and modified version of Stug III, designed as eventual replacement for it. The new vehicle was designated as Sturmgeschutz neuer Art mit 7.5cm PaK L/48 auf Fahrgestell PzKpfw IV (Sd.Kfz.162) but was also known as Jagdpanzer E 39 and more commonly as Jagdpanzer IV. Work on its design took place in early 1943 and on May 13th of 1943, Vomag .(Vogtlandische Maschinenfabrik AG of Plauen) produced a wooden mock-up, which was show to Hitler in September of 1943. The main role of the new vehicle was to be a tank destroyer. First soft steel prototype was ready in October of 1943, which was then shown to Hitler as well. In December of 1943, final prototype of Jagdpanzer IV was ready and Vomag was ordered to start production as soon as possible.
The first vehicles of 0-Serie (pre-production test series) had front plate with rounded sides (curved corners) and were armed with 75 mm Pak 39 L/43 gun without muzzle break. First production vehicle was produced in January of 1944, on modified PzKpfw IV Ausf F chassis and was designated as (leichter) Jagdpanzer IV Ausf F (Sd.Kfz.162). It was armed with 75 mm Pak 39 L/48 gun (with muzzle break) and two 7.92 mm MG42 machine guns. Due to the production problems with 75mm L/70 gun and its adaptation for use in Jagdpanzer IV, readily available 75mm L/48 gun was mounted instead. As a result of slow development of Jagdpanzer IV and great need for new armoured fighting vehicles new vehicle was created. It was done by installing modified Stug III superstructure on PzKpfw IV chassis creating Sturmgeschutz IV, which was used in the same manner as Stug III. Work on 75mm L/70 armed Jagdpanzer IV began in January of 1944 and lasted until April of 1944. Work on second Jagdpanzer IV armed with 75 mm L/70 gun started in June of 1944 and ended in July of 1944. Both vehicles then entered production in August of 1944.