IS-1

The IS-2 tank first saw combat in early 1944. IS-2s were assigned to separate heavy tank regiments, normally of 21 tanks each. These regiments were used to reinforce the most important attack sectors during major offensive operations. Tactically, they were employed as breakthrough tanks. Their role was to support infantry in the assault, using their large guns to destroy bunkers, buildings, dug-in crew-served weapons, and other 'soft' targets. They were also capable of taking on any German AFVs if required. Once a breakthrough was achieved, lighter, more mobile T-34s would take over the exploitation.

The IS-3 first appeared to Western observers at the Allied Victory Parade in Berlin in September 1945. The IS-3 was an impressive development in the eyes of Western military observers, the British in particular, who responded with heavy tank designs of their own.

By the 1950s the emergence of the main battle tank concept—combining medium-tank mobility with the firepower and later armour of the heavy tank—had rendered heavy tanks obsolete in Soviet operational doctrine. In the late 1960s the remaining Soviet heavy tanks were transferred to Red Army reserve service and storage. The IS-2 Model 1944 remained in active service much longer in the armies of Cuba, China and North Korea. A regiment of Chinese IS-2s was available for use in the Korean War, but saw no service there. In response to border disputes between the Soviet Union and China, some Soviet IS-3s were dug in as fixed pillboxes along the Soviet-Chinese border. The IS-3 was used in the 1956 Soviet invasion of Hungary and the Prague Spring in 1968.

During the early 1950s all IS-3s were modernised as IS-3M models. The Egyptian Army acquired about 100 IS-3M tanks in all from the Soviet Union. During the Six Day War, a single regiment of IS-3M tanks was stationed with the Egyptian 7th Infantry Division at Rafah and the 125th Tank Brigade of the 6th Mechanized Division at Kuntilla was also equipped with about 60 IS-3M tanks. Israeli infantry and paratrooper units had considerable difficulty with the IS-3M when it was encountered due to its thick armour, which shrugged off hits from normal infantry anti-tank weapons such as the bazooka. Even the 90 mm AP shell fired by the main gun of the Israeli Defense Force (IDF) M48 Patton tanks could not penetrate the frontal armour of the IS-3s at normal battle ranges. There were a number of engagements between the M48A2 Pattons of the IDF 7th Armoured Brigade and IS-3s supporting Egyptian positions at Rafah in which several M48A2s were knocked out in the fighting. However, in one engagement between a battalion of IS-3s and 90MM-gun-armed M48A3's, 7 IS-3s were destroyed. The slow rate of fire, poor engine performance (the engine was not well suited to hot-climate operations), and rudimentary fire control of the IS-3s proved to be a significant handicap, and about 73 IS-3s were lost in the 1967 war. Most Egyptian IS-3 tanks were withdrawn from service, though at least one regiment of IS-3 tanks was retained in service as late as the 1973 October war. The IDF itself experimented with a few captured IS-3M tanks, but found them ill-suited to fast-moving desert tank warfare; those that were not scrapped were turned into stationary defensive pillbox emplacements in the Jordan River area.

After the Korean War, China attempted to reverse-engineer the IS-2/IS-3 as the Type 122 medium tank. The project was cancelled in favour of the Type 59, a copy of the Soviet T-54A.

IS-1
Class Vehicle
Type Armoured Fighting Vehicle
Manufacturer Factory No.100 Kirovskiy Works in Chelyabinsk
Production Period 1943 - 1944
Origin Russia (USSR)
Country Name Origin Year
Russia (USSR) 1943
Country Name Operational Year Retirement Year
Russia (USSR) View
ManufacturerName Production From Production To Quantity
Factory No.100 Kirovskiy Works in Chelyabinsk 1943 1944 107 View

The IS Tank was a series of heavy tanks developed as a successor to the KV-series by the Soviet Union during World War II. It was named after Soviet leader Joseph Stalin. The heavy tank was designed with thick armour to counter the German 88 mm guns, and carried a main gun that was capable of defeating the German Tiger and Panther tanks. It was mainly a breakthrough tank, firing a heavy high-explosive shell that was useful against entrenchments and bunkers. The IS-2 was put into service in April 1944, and was used as a spearhead in the Battle of Berlin by the Red Army in the final stage of the Battle of Berlin.

The KV-1 was criticized by its crews for its poor mobility and lack of any heavier armament than the T-34 medium tank. It was much more expensive than the T-34, without having greater combat performance. This led Moscow to order a portion of KV-1 assembly lines to shift to T-34 production, which fed into fears that KV-1 production would be halted and the SKB-2 design bureau led by Kotin closed. In 1942 this problem was partially addressed by the lighter, faster KV-1S tank. The production of the KV-1S was gradually replaced by the SU-152 and ended completely on April 1943. However, the capture of a German Tiger tank in January 1943 led to a decision to develop a new heavy tank, which was given the codename Object 237.

In response to intense tank fighting in the summer of 1943, while the Objekt 237 was still in development, Dukhov's team was instructed to create a stopgap KV tank, the KV-85, which was armed with the 52-K-derivative gun of the SU-85, the 85 mm D-5T that proved capable of penetrating the Tiger I from 1000 meters. The KV-85 was created by mounting an Object 237 turret on a modified KV-1S hull. This necessitated increasing the diameter of the turret ring by adding fillets to the sides of the hull. The radio operator was removed and in his place was inserted an ammo rack for the larger 85 mm ammunition. The hull MG was then moved to the opposite side of the driver and fixed in place to be operated by the driver himself. Soviet industry was therefore able to produce a heavy tank as equally well armed as the Tiger I before the end of 1943. There was a short production run of 148 KV-85 tanks, which were sent to the front beginning in September 1943 with production ending by December 1943. The complete Objekt 237 prototype, itself an evolution of the cancelled KV-13, was accepted for production as the IS-85 heavy tank. First deliveries were made in October 1943 and went immediately into service. Production ended in January 1944. Its designation was simplified to IS-1 after the introduction of the IS-122, which itself was redesignated to IS-2, for security purposes.

GENERAL DATA
Other DesignationsIS-1 [IS - Iosef Stalin, also IS-85, and JS-1]
Manufacturer(s)Factory No.100 Kirovskiy Works in Chelyabinsk (ChKZ or Tankograd)
Production Quantity1071Production PeriodLate 1943 - Early 1944
TypeHeavy TankCrew4
Overall Length8.3 m (27' 3")Barrel Overhang1.6 m (5' 3")
Width3.1 m (10' 2")Height2.7 m (8' 10")
Combat Weight44000 kg (97000 lbs)Radio Equipment10R or 10RK
FIREPOWER
Primary Armament85mm Gun D-5T85Ammunition Carried59
Traverse (degrees)360°Elevation (degrees)-4° to +23°
Traverse speed (360°)n.a.Sight10T-15, PT-4-15
Secondary Armament3 x 7.62mm DT MG
(coaxial, turret rear, bow)
Ammunition Carried2520

MOBILITY CHARACTERISTICS
Engine Make & ModelV-2-IS (V-2K)Track Links87-90/track
Type & DisplacementV12, 38.9 litersTrack Width65 cm (26")
Horsepower (max.)600hp@2000rpmTrack Ground Contact436 cm (172")
Power/Weight Ratio13.6 hp/tonneGround Pressure0.78 kg/cm2 (11.1 psi)
Gearbox4 forward, 1 reverseGround Clearance0.46 m (1' 6")
FuelDieselTurning Radius0
Range on road150(260) kmGradient36°
Mileage on road330 l/100kmVertical Obstacle1.0 m (3' 3")
Fuel Capacity520 (+ 360 external)2 lFording1.3 m (4' 3")
Speed on/off road37/19 km/hTrench Crossing2.5 m (8' 2")
ARMOR PROTECTION
Armor DetailFrontSideRearTop/Bottom
Hull100mm@60°90mm@90°60mm@49°30mm@0°(front)
60mm@18°(glacis)20mm@0°(back)
Superstructure120mm@60°(driver)90mm@75°60mm@41°30mm@0°
Turret100mm@round100mm@72°100mm@60°30mm@0-5°
Mantlet100mm@round---
NOTES
1At least 102 of these vehicles were later rearmed with the 122mm D-25 gun. It is unclear whether any of the vehicles with the original configuration were actually used in combat.
2It is assumed here that the four 90 liter tanks were all used for fuel.

End notes