Panzer IV Lang (long gun) versions was contemplated since mid-1930s, but its necessity was urgently needed by 1941 when Germans encountered Soviet T-34 tanks which could not be readily defeated by the short-barrel 7.5cm gun. First up-gunned version was commonly known as Panzer IV Ausfuhrung F2 armed with 7.5cm KwK40 L/43 gun, as shown above with German Grossdeutschland Panzer Division, Summer 1942, in rolling steppes of Soviet Union. Grossdeustchland (Greater Germany) in this instance referred to Germans enlisted from throughout Germany rather than from a specific military recruitment region. Note Panzertruppen above wear field green rather than traditional black uniforms, field caps remain black. Großdeutschland Division - en.wikipedia.org/wiki/Grossdeutschland_Division

Grossdeutschland (or Pan-Germanism) was also a socio-political concept of unifying all German tribes within one realm since formation of modern nation-states in past 200 years fragmented German ethnic groups among multiple Europe countries, in which some felt their ethnic, religious, and political rights were being diluted or abrogated. From an average German perspective, WW2 was less about fascism versus democracy, and more about tribal unification, ethnic solidarity, and formation of a new socialist order to supplant corrupt capitalism. Großdeutschland - en.wikipedia.org/wiki/Grossdeutschland

WW2 German military nomenclature were very descriptive, but can be maddening to memorize (to use a British slang). Originally, Panzer IV Lang-versions were called 7/Begleitwagen-Umbau (7th series companion wagon conversion). Next changed to Panzerkampfwagen IV Ausfuhrung F-Umbau (shortened to Pzkpfw IV Ausf F-Umbau) for Tank (or metal-boxed fighting vehicle) version IV model F conversion. Then to designation Panzerkampfwagen IV Ausfuhrung F2 (SdKfz 161/1) to distinguish it from short-barrel F1 versions. SdKfz was German acronym for SonderKraftfahrzeug (special purpose vehicle built for military use), all German military armored vehicles had this designation.

Rollover : 3rd Panzer Division Panzer IV Ausf H in winter white-wash camouflage (white paste mixed with water, brushed onto tank, fades and flakes readily after prolong exposure), armed with long-barrel 7.5cm KwK40 L/48 gun. Note Berlin Bear caricature overlay German national cross on turret schurzen (armored side skirts). By 1943, Panzer IVs began carrying schurzen on turret and hull areas to serve as applique armor (it generally forced shaped-charged enemy warheads to detonate on the skirts rather than the tank). Appliqué Armour - en.wikipedia.org/wiki/Appliqué_armour

Panzer IVs were regularly upgraded with new design and armament, with about 8500 being produced among all model types, it was the most numerous German WW2 tank manufactured. By 1944, hull design was simplified to accelerate mass production (Germans slow to adopt American-style mass production due to their engineering mindset that mass production equates to poor quality product), while gun barrel was lengthened to increase firepower from the short L/24 to L/43 and L/48 long versions (longer barrel meant more propellant gas compression, thus longer range of tank shell). There was a physical limit lengthening the barrel before accuracy was compromised from yawing (shaking after firing) or warping (bending from hot exhaust gas).

Panzer Colors 1 Camouflage of the German Panzer Forces 1939-45 ( ISBN: 0-89747-057-5 )