By 1945, the Pzkpfw IV was, however, the only basic tank design of pre-1940 origin still in major service in Europe - with any army. The pace of development was such, under the impetus of war, that all other pre-1940 designs were very quickly rendered obsolete in the early years of the conflict. What ensured the everlasting quality of the Pzkpfw IV in the face of rapid technological change was its reliability and its size.
Back in 1940, by contrast, it was the early models of the Panzer IV which were the most impressive vehicles in the victorious panzer divisions. It was these tanks in the propaganda pictures and the newsreels which did most to foster the legend of the invincibility of the German armoured forces which spearheaded the blitzkrieg assaults. At this time the Panzer IV was being used in its intended role, as conceived by General Guderian when he organized the German panzer divisions in the late 1930s. The concept for what became the Pzkpfw IV went back to a policy meeting held in January 1934 by departmental heads of Heereswaffenamt (Wa Pruf 6), the German ordnance department section responsible for organizing the new armoured divisions, envisaged light training and recce tanks (which eventually resulted in the Pzkpfw I and II) and a close support tank, able to fire high explosive and smoke shells. There was a the time an absolute weight limit of 24 tons to meet existing road bridge limitations. Because Germany was not officially allowed to have tanks at that time, a 'camouflage' name was used for this type of vehicle - Battaiilonsfuherwagen (BW for short), or battalion commander's vehicle. Later in 1934, leading arms and automotive firms in Germany were asked to submit designs which met the outline requirement which Wa Pruf 6 had drawn up. A mild steel prototype VK 2001, by Rheinmetall-Borsig, was put forward late in 1934 to meet the BW requirement, but it was another prototype vehicle, the MKA, built by Krupp in 1935, that eventually formed the basis for the design.
The overhanging superstructure and generous access hatches made the Pzkpfw IV (as it was subsequently designated) a very roomy vehicle with good ammunition stowage. For its time the Pzkpfw IV was very well equipped with excellent vision for all crew members and comprehensive fire control systems. The early models were built in small batches only, starting with Ausf (model) A in 1937-39 of which 35 were built. Some 45 of the next model, Ausf B, were built, these having a more powerful Maybach engine (up from 250 HP to 320 HP) and increased front armour. Over a hundred Ausf C were built followed by over 200 Ausf D, and it was models C and D which served in the Polish, Norwegian, and French campaigns in the 1939-40 period. New features on the Aust D included an external gun manlet, with 35mm armour shield, a gimbalmounted hull machine gun in an armoured mount housing, and a distinctive staggered front superstructure with the driver set forward. While this was the basic Pzkpfw Ausf D of 1940, there were many later retrospective modifications, and these included the fitting of anew pattern drive sprocket, wider tracks longer tracks and extra armour (30mm front, 20mm sides) in the from of plates bolted to the superstructure.