The Panzer III represented half of that future. Its design orders were first issued in 1935, and for security purposes it was initially designated “platoon commander’s vehicle.” The first four prototypes, offered by four different firms, were tested in late 1936. The winner was Daimler-Benz, but the contract proved a mixed blessing. The original specifications were for a tank weighing 15 tons and capable of 25 miles per hour. Daimler made the weight by limiting the armor to Panzer II levels, and adapted a suspension system from its civilian vehicles that restricted the speed to 20 miles per hour. The result was more tinkering. A reworked suspension and a more powerful engine improved the speed even when the armor was increased to as much as 30mm, offering reasonable protection against large fragments from artillery shells and glancing hits from antitank rounds. The design’s final weight was 19.5 tons—still well below the 24 tons that were the limit of German field bridges.
All this took time. The Panzer III went through no fewer than four type designations before the Model E was considered sufficiently refined to manufacture in some numbers. Even then the first general-production version of the tank was one letter later. The Mark F went into production in September 1939—just too late for the Polish campaign.
Replacing the panzers’ material losses was not a simple one-for-one process. The workhorse Panzer III was increasingly outclassed by its Soviet opponents—less from any qualitative improvement than because the Russians were beginning to learn how best to take tactical advantage in particular of the T-34’s powerful gun and high maneuverability. The Panzer III’s chassis was too light, its turret ring too small, to be a useful transition to the next panzer generation. They were issued as stopgaps, and by mid-1943 appeared in no more than company strength.
The Panzer IV, in contrast, had a future. Improved muzzle braking enabled it to carry the 43-caliber Tank Gun KwK 40, and a more powerful 48-caliber version introduced in late 1942. More than 1,700 of these F and G models were produced or upgraded before they gave way in March 1943 to the definitive late-war Panzer IVH. Its armor was significantly increased: 80mm on the front and 50mm on the turret, 30mm on the sides and 20mm in the rear—the latter reflecting Red Army infantrymen and antitank crews’ willingness to come to close quarters for a kill. The additional protection increased weight to 25 tons and reduced speed to 21 miles per hour, but the Model H could still move and maneuver well enough. Its 75mm, 48-caliber gun was roughly equivalent to the T-34’s main armament, and effective against almost anything it could reach.
The Panzer IVH/J integrated a useful set of upgrades into a state-of-the-art light medium tank, intended to equip one battalion in each panzer division. More than 3,000 would be built in 1943, and more than 3,100 in the war’s final 18 months. They were nevertheless regarded as stopgaps, holding the line for a new generation of exponentially more powerful armored fighting vehicles.