Grw. 120mm is a German Artillery unit.
12 cm Granatwerfer 42 was created for the German Infantry to have a close support weapon with greater performance than the mortars in current at that time service. This mortar was a copy of the Soviet 120-PM-38 120mm Mortar since the axis forces captured large quantities of them and found them useful toward their former owners.
The Grenadier Battalions had one 12 cm Mortar Platoon in either Machine Gun Company or the Heavy Company with the planned strength of four 12 cm mortars. The Panzer Grenadier Battalion has their 12-cm Mortar Platoon in the Heavy Company also with the strength of four 12 cm mortars. In the Armored Panzer Grenadier Battalion are transported by SdKfz 251/1. While the Motorized Panzer Grenadier Battalion use half-track tractors or lorries.
Fallschirmjäger Regiment by proper organization should have a Heavy Mortar Company of three platoons of three 12 cm Mortars. Fallschirm-Granatwerfer-Bataillone 3 was created and destroyed in Normandy.