A purpose built support weapon, replacing the Ausf H. Using it's 15 cm Howitzer to soften up targets in preparation for infantry assaults.
SdKfz 138/1 Grille Ausf K/M
The German Army used the sIG 33 15cm infantry gun as a close support weapon to smash enemy strongpoints. However, the guns large size meant it was difficult to manhandle.
It also needed a large team of horses or a powerful tractor to move it any great distance. This was a major drawback for such an important weapon in the Panzer and Panzergrenadier divisions.
An interim solution to the mobility problem was found by mounting the whole gun on top of a Pz I chassis with a large superstructure around the front and sides.
Although it was unwieldy it worked! Later in 1942 a better solution was designed that used the Pz38(t) chassis with the gun mounted in an open topped compartment.
90 of this Ausf H (Grille H GE143) version were built and issued to the Panzergrenadier heavy infantry gun platoons from February 1943 and some were still in service in Normandy in 1944.