Developed in 1942, the 12 cm (about 4.7 in) GrW 42 was an attempt to give German infantry units a close support weapon with greater performance than the mortars used in general service at the time.

The 120 mm Brandt m35 was used in limited quantities during the Battle of France and exported to the USSR and other nations before the country's capitulation in 1940.

The Soviet PM 38 120 mm mortar, were captured in large quantities during the war in the East and pressed into service by the Germans and other Axis nations before the introduction of similar nationally produced 12 cm mortar designs.

[3] The GrW 42 was basically the usual three-part construction made up of a circular base plate like the previous Soviet design, the tube itself and the supporting bi-pod.

Because of the greater weight of the weapon (280 kilograms or 620 pounds) a two-wheeled axle was utilized, enabling the mortar to be towed into action.