Soon after the German invasion of the USSR in 1941, "Wehrmacht" units encountered new Soviet tanks, the medium T-34 and the heavy KV. The thick and/or sloped armor of these vehicles gave them invulnerability against German towed 3.7 cm Pak 36 anti-tank guns. The situation led to requests for more powerful weapons that would be able to destroy them at normal combat ranges. Since Germany already had a suitable design, the 7.5 cm Pak 40, this weapon entered production and the first pieces were delivered in November 1941. However, until enough of these were manufactured, some expedient solution was required.