The 15cm schweres InfanterieGeschutz 33 (sIG33) was designed and built to fulfill the requirement for a powerful, close support gun for the infantry. The German Army preferred infantry support guns rather than the mortar that most other countries tended to favor for this kind of role.
The design was conventional but rather heavy for its intended purpose. Originally intended to be horse drawn, later versions had rubber-tired wheels and air brakes to allow them to be towed by vehicles. Attempts were made to lighten the gun but not many of this version were made, as the alloys needed for the job were more essential to aircraft production.
It could fire a 38kg (84lb) HE or smoke shell out to 4700m at the rate of 2-3 rpm. A hollow charge round was developed but was mainly used to destroy bunkers and other fortifications. A Steilgranate round was developed as well but was also rarely used.