The Soviet Union needed upgrades in their armored forces to withstand the newer German Tanks like the Tiger I and Panther tanks. In February 1944 plans developed for a new version of the SU-85 tank destroyer. The 85 mm guns became obsolete after the introduction of the newer generation German tanks.
The T34 chassis was chosen as it was with the SU-85. The newly developed D-10S 100 mm anti-tank gun was used in a casemate like superstructure on top of the T-34 chassis. The first prototype was presented in March 1944 and it used in the Soviet army from Oktober 1944. The Soviets placed a circular viewing tower on the upper structures side for the commander. This gave the SU-100 a great advantage over its foreign counterparts like the Stug III or Jagdpanther and other tanks destroyers without a cupola.
The name during development was Object 138 before it was changed into SU-100. SU comes from Samokhodnaya Ustanovka the name refers to a casemate self-propelled gun like the SU-76.
The newly developed anti-tank gun D-10S used on the SU-100 could penetrate a German Tiger I tank at 2000 meters and the sloped frontal armor of the Panther at 1500 meters. Its frontal armor was 75 mm inclined at 55 degrees making it effective at 125 mm thickness. This forced older German tanks like the Panzer IV and the StuG III to close in at point blank range to penetrate the US-100 frontal armor. The Tiger I had to close in under 1000 meters, giving the SU-100 a great advantage until it was outmatched by the Tiger II tank, the King Tiger.
The SU-100 was also used to break through fortifications even though it wasn’t developed for this role. It always needed infantry support and air support for it lacked close defense capabilities, there weren’t any machineguns installed. The SU-100 had a crew of 4 and reached speeds up to 48 km/h with a maximum distance of 140 km, 180 km with extra fuel tanks.
SU-100 in Musea
Almost 8.000 units were produced and it was used and produced long after the Second World War. It was built under license by Czechoslovakia, these self-propelled guns are well seen in European museums. There are on display as the Soviet SU-100 Tank Destroyer but are in fact Czechoslovak SD-100 tanks like the ones in MM-Park museum in France, or Músee des Blindes also in France, the Tank Museum in Munster Germany or the Tank Museum in Bovington England. The original Russian SU-100 Tank Destroyers are a bit harder to find in western Europe, but they are there. Like this one photographed in front of the Ravensbrück Concentration Camp.