The PaK 36 (Panzerabwehrkanone 36) was a German anti-tank gun that fired a 3.7 cm calibre shell. In-game, the PaK 36 is the most basic weapon in the German anti-tank base. However, its effectiveness is limited, so it is advised to immediately upgrade to the PaK 40 when enemies begin producing heavy tanks.
Design of a horse-drawn, 3.7 cm anti-tank gun (designated 3.7 cm PaK L/45) by Rheinmetall commenced in 1924 and the first guns were issued in 1928. By the early 1930s, it was apparent that horse-drawn artillery was obsolescent, and the gun was modified for motorized transport by substituting magnesium-alloy wheels and pneumatic tyres for the original spoked wooden wheels. Redesignated the 3.7 cm PaK 35/36, it began to replace the 3.7 PaK L/45 in 1934 and first appeared in combat in 1936 during the Spanish Civil War.
It formed the basis for many other nations' anti-tank guns during the first years of World War II. The KwK 36 L/45 was the same gun but was used as the main armament on several tanks, most notably the early models of the Panzer III. It was employed by Finnish troops during World War II, notably during the Defense of Suomussalmi.
The PaK 36, being a small-calibre weapon, was outdated by the May 1940 Western Campaign, and crews found them all but useless against heavy allied tanks like the British Mk.II Matilda and the French Char B1 and Somua S35. A group of these guns claimed to have knocked out a Char B1 by firing at its flank. The PaK 36 can penetrate 35 mm sloped armor at 30 degrees. The Char B1's side armor was 40 mm. However, it was vertical. Thus it could be penetrated by Pak 36 only when fired within 100 m and at a right angle from the side armor.
This was very difficult to achieve in battlefield conditions. Still, the gun was effective against the most common Allied pre-war light tanks, such as the FT-17 during the Battle of France and the T-26 during Operation Barbarossa. The widespread introduction of medium tanks quickly erased the gun's effectiveness; miserable performance against the T-34 on the Eastern Front led to the PaK 36 being derisively dubbed the "Door Knocker" ("Heeresanklopfgerät", literally "army door knocking device") for its inability to do anything other than advertise its presence to a T-34 by futilely bouncing rounds off its armor.