After the might of the German Army had pressed deep into Soviet Russia, it was stopped at the gates of Moscow by a lack of supplies and bad weather. This lull is the action allowed the Soviets to rebuild their strength and call upon fresh reserves stationed in the far east and across Siberia. The Soviet counter-offensive in the winter of 1941 also brought about use of the new T-34 Medium Tank which stunned both German tankers and anti-tank crews alike with its thick armor and fast cross-country performance. The tank, coupled with the weather and Soviet tank doctrine and tactics, all worked against the German invaders and in favor of the Soviet defenders whom were vastly better equipped for such a battlefield than their foe. The summer of 1942 saw an end come to the German overall invasion plan of taking Russia proper and the following winter only yielded more heavy losses for the beleaguered Germans. The Kursk Offensive of 1943 became the last large-scale German thrust against the now-established momentum of the Red Army.
To compensate for the mounting losses, German authorities called for improved tanks - particularly where armor protection and penetrative weaponry were concerned. The response eventually yielded the Panther Medium Tank as well as the highly respected Tiger I and Tiger II Heavy Tanks. To counter the German counter, the Soviets moved to designing family of tracked vehicles with their own increasingly effective armament arrangements and one of these creations became the "SU-100" tank destroyer.
The SU-100 originated through the plain and simple need from the Soviet Army needing to combat the latest generation of German tanks now being fielded across the Eastern Front. Soviet engineers responded by developing a new gun based around the existing - and proven - B-34 naval gun utilized on Soviet warships of the time. To help improve development time, the natural selection of the T-34 chassis was made to ensure the gun could be mounted onto a readily available and proven tracked system. Nearly three quarters of the new vehicle would be made up of the T-34 while the remaining quarter would be largely unique to the new tank destroyer. Design and development of the tank destroyer - designated as the SU-100 (the "100" is derived from the caliber of the main armament) - began in early 1944. The gun was itself designated as the "D-10" in its basic form and, became the D-10T when fitted to a tank while becoming the D-10S when fitted to a self-propelled artillery vehicle. Despite their associated designations, the guns were differentiated largely by the choice of mount required for each installation - tank versions fitted into traversing turrets while self-propelled forms fitted into fixed superstructure hulls. Two pilot vehicles - the "SU-100-1" and the "SU-100-2" - was made ready for testing in March of 1944.
After successful evaluation, the vehicle was quickly accepted into frontline service with the Red Army under its well-known and general "SU-100" designation. Its overall design was rather conventional which much of the hull appearance of the T-34 left largely intact. The key differentiating feature of the SU-100 was its fixed superstructure hull which housed the needed gun mount for the 100mm main gun. The 100mm main gun protruded from the front facing of the vehicle and held limited traversal and elevation, requiring the crew to face the entire tank in the direction it needed to fire. The crew, applicable internal facilities and the engine were all housed under the enclosed armor structure. The driver sat at the front left with the gun to his immediate right. The crew of four also included the tank commander, gunner and an ammunition handler. The glacis plate of the vehicle was efficiently sloped for basic ballistics protection while the sides of the hull superstructure were angled inwards with the hull roof left flat. There was a raised cupola to the right side on the hull roof for the commander and completed with useful vision slots. Another hatch was set to the cupola's left, just aft of the driver's position for the loader. The hull superstructure only ran up to the midway point of the design to which the lower engine compartment was fitted to the rear. The engine exhausted through a pair of pipes at the rear facing which was also sloped inwards, giving the SU-100 its distinct all-around shape. As the T-34 before it, the SU-100's frame made use of five large, rubber-tired road wheels to a track side with the requisite track idler and drive sprocket at either end. The chassis was suspended by a conventional Christie-type suspension system for improved cross-country performance. SU-100s were commonly seen with two or four external fuel drums hooked up to the upper sides of the hull rear - this helping to extend the operational range of the vehicle in keeping up with the main force. All told, the SU-100 was an imposing looking battlefield system - built of Soviet expertise and war time experience.
Primary armament of the SU-100 centered around the use of the potent 100mm D-10S main gun. The system was installed onto a specially engineered mount that made for a rather complex overall system. 33 x 100mm projectiles were typically carried on a given SU-100 and this was usually divided into a standard issuing of 18 x AP (Armor-Piercing) rounds and 15 x HE/FRAG (High-Explosive / Fragmentation) rounds allowing the SU-100 crew to tackle both "hard" armored and "soft" targets. High-explosive ordnance proved highly effective when engaging concentrations of dug-in troops and light-armored vehicles and was issued on nearly every armored fighting vehicle of the war. Interestingly, no thought was given to arm the SU-100 crew with self-defense machine guns - making her susceptible to both enemy infantry attacks and low-flying aircraft.
Power for SU-100s were provided for by the inclusion of a V-2-34M series 12-cylinder, 4-stroke diesel-fueled engine of 500 to 520 horsepower tied to a five-speed transmission system. This allowed the vehicle to reach top speeds of 30 miles per hour over ideal terrain and out to 200 miles of distance - in line with fast-moving Soviet armored doctrine of the time.
In practice, the SU-100 proved her value to Red Army forces, especially when fielded with supporting infantry and armor. Some 65 systems were issued to self-propelled artillery brigades to help bolster the lines. A well-trained and experienced crew could loose up to six rounds per minute from a fighting compartment that was not unlike the T-34 itself - save for the lack of a turret. Engagement was through a pair of sights - one being panoramic and the other telescopic in design - and made for a highly effective tank killer. The D-10S gun could now match German armor as thick as 125mm at ranges out to 6,500 feet with lethality being increased against armored targets within 3,200 feet. First contact action with the enemy regarding SU-100s occurred in March of 1945 in Hungary against German armor where the Soviets prevailed at Lake Balaton.
All was not well for the SU-100 design, however, for initial production models shown some inherent limitations. The complicated gun mounting system led to extended production times that also resulted in sub-par penetration performance of the gun itself when in the field. The problem was not rectified until the end of 1944 by which time the D-10S delivered - on the whole - as promised. Natural teething issues also played a role in limited success very early on. However, once the SU-100 was cleared of its issues, it made for an excellent German tank killing system allowing full production to be reached by the end of 1944 and into 1945. Consider the lack of self-defense weaponry and the SU-100 needed to be sent into battle with accompanying ground infantry for point protection. It was common practice for enemy infantry to swarm a defenseless tank through grenade attacks and attempt to flush out tanker crews, only to shoot them as they exited the vehicle.
It is believed that some 2,335 to 3,000 SU-100s were ultimately produced, allowing the vehicle to stock the inventories of several Soviet-allied nations in the Cold War years. In fact, Soviet production spanned into 1947 - a full two years after the world war was over, such being the value of the nimble little system. Czechoslovakia continued local production of the SU-100 up to 1957. Other operators included Albania, Angola, Bulgaria, Cuba, East Germany, Egypt, Hungary, North Korea, Poland, Romania, Vietnam and Yugoslavia. In Yugoslavian service, the SU-100 went under the designation of "M-44". A tropicalized version intended for desert warfare emerged as the "SU-100M" - the "M" used to showcased its "modified" form. The Egyptians fielded their SU-100s in a large part during the Suez Crisis of 1956, the Six Day War of 1967 and the Yom Kippur War of 1973 and these vehicles proved adequate for their intended role. Likewise, those SU-100s in Yugoslavian service were used for a short time the local civil war until maintenance issues resulted in their removal from active service. For some global forces in the world today - including North Korea and China - the SU-100 remains a viable tank destroyer implement.
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