The sIG 33 Bison was a self-propelled artillery piece employed by the German Army during World War II. The official name in German was 15-cm sIG 33 auf Geschützwagen I. It was the standard 150-mm heavy field howitzer, which was mounted on the chassis of the Panzer I tank (PzKpfw I). 'sIG' stands for 'schwere Infantrie Geschütz 33', which is German for 'heavy infantry gun model 1933'. It first saw combat action in May 1940 during the Battle of France.
With the creation of motorized and mechanized infantry divisions for the Blitzkrieg, the need for mobile artillery arose. The 150 mm infantry field howitzer and other artillery pieces were too heavy and they needed up to three pairs of mules/horses to haul them around the battlefield. Since they were used as fire support weapons, their cumbersomeness slowed down the advance of the infantry spearhead. The first sIG 33 auf Geschützwagen I self-propelled artillery pieces entered service in early December 1939. Despite some mechanical problems that cropped up along the way, they were successfully used during Fall Rot in Holland, Belgium, and France in 1940.
Below, the sIG 33 Bison first version on Panzer I
At the end of the Battle of France, a problem came up, and it was not mechanical. the sIG 33 Bison had been mounted on a high platform, with tall armor plates to protect the crew. These features gave the Bison a high center of gravity and, above all, a high profile on the horizon of the battlefield as several of them were destroyed by the French 75-mm field gun and the Char B1 tank gun. Therefore, the mechanical problems and the high profile it had led the German Army engineers to mount the same artillery piece, the 15-cm sIG 33, on the chassis of the Panzer II and III, and Panzer 38(t). This is how new versions of Bison arose, such as the sIG 33 auf PzKpfw II Type II B, the Type F, and Type H.
Specifications
Type: self-propelled infantry support howitzer.
Weight: 11.5 and 13 tons, depending on the variant.
Length: 4.8 m
Width: 2.2 m
Height: 2.4 m
Power Plant: one Praga, 6-cylinder, 150-HP, gasoline engine.
Range: 190 km
Maximum Speed: 35 km/h
Armament: one 15-mm-caliber howitzer.
Crew: 4 soldiers.
Below, the sIG 33 Bison Type I A on the battlefield, still on the chassis of the Panzer I tank.
The sIG 33 Type II B on the Panzer II chassis.
Below, the Type F, the 15-cm schwere Infantrie Geschütz auf PzKpfw III
