To get more artillery to be self propelled chassis from light and medium tanks were converted to carry a 15 cm infantry gun. They were successful as they could be brought into action quicker than a horse or vehicle towed howitzer.7
By late 1943 these were withdrawn from combat as they were being replaced by other assault weapons.7
15 cm siG33 (Sf) auf PzKpfw I Ausf B; GW 1 für 15cm sIG 33; 15cm sIG 33 auf Geschuetzwagen I Ausf B: Alkett converted 38 PzKpfw I Ausf B in mid 1939.5 Had entire carriage and wheels of 150 mm howitzer mounted.7,8 Had shield to partially protect crew.7,8
15 cm siG33 auf Fahrgestell PzKpfw II (SF); 15cm sIG 33 auf Fgst PzKpfw II (Sf) Verlaengert; GW II für 15cm sIG 33: Used a modified PzKpfw II chassis.8 It was widened and lengthened and an additional wheel was added.7 Range of 4,700 meters. The 150 mm gun could fire a 36.8 lb HE shell at a muzzle velocity of 790'/sec.4
Sturminfanteriegeschütz 33B, 15 cm s.I.G. 33 on PzKpfw III; Sturm-Infantriegerschütz 33B Sfl; 15cm sIG 33 auf Pz III; StuIG 33 auf Fgst PzKpfw III: Made from PzKpfw III chassis.7 Howitzer was completely enclosed.7
15 cm siG33 (Sf) auf PzKpfw I Ausf B
Used in Poland, France in 1940, and in Russia.7 Equipped sIG Kompanien (heavy infantry gun companies) 701-706 and were used in Belgium, Holland, and France in 1940. The last ones in service were with the 704th schwere Infanteriegeschütz Abteilung of the 5th Panzer Division in Russia in mid-1943.
15 cm siG33 auf Fahrgestell PzKpfw II (SF)
All were shipped to North Africa in 1942 to the 707 and 708 sIG Kp (SF) (heavy infantry gun companies). Took part in the Gazala spring offensive.