This article is about the history of the German 3.7 cm L/45 guns — mainly the PaK 36* and KwK 36 — as well as the tangentially related Navy 3.7 cm FlaK M42 L/69. The PaK 36 was the mainstay of towed anti-tank guns for Germany during World War II, being used from the war’s onset until the last days of the war, and were used in all sorts of roles, ranging from anti-tank operations in the late 1930s to infantry support using HE and fin-stabilized HEAT grenades during the closing days of the war. While the PaK 36 and its derivatives were largely obsolete by the end of World War II, their large production volume (20,000 units) meant that it wasn’t too hard to find them across various frontlines, still putting in work.