The BMM factory in Prague was developing a mid-engine Pz.Kpfw.38(t) chassis for use as a dedicated self-propelled gun (eventually named the Grille Ausf.M), but this program met with delays. In the interim it was decided to mount the 15cm s.IG.33 gun on 90 or so existing rear-engine Panzer 38(t) chassis in order to get the weapon into service as soon as possible. The resulting Grille Ausf.H was produced from February to April 1943, and it was widely used in German panzergrenadier regiments until the end of WWII.