The ISU-152 (, meaning "IS tank based self-propelled installation with 152mm caliber gun") is a Soviet self-propelled gun developed and used during World War II. It was unofficially nicknamed Zveroboy (; "beast killer") in response to several large German tanks and guns coming into service, including Tigers and Panthers. Since the ISU-152's gun was mounted in a casemate, aiming it was awkward, and had to be done by repositioning the entire vehicle using the tracks. Therefore, it was used as mobile artillery to support more mobile infantry and armor attacks. It continued service into the 1970s and was used in several campaigns and countries. History The beginnings of the ISU-152 came on 24 January 1943, when the first prototype of the SU-152 was unveiled. This was a fully enclosed 152mm gun-howitzer on the KV-1S tank chassis. It was designated ("Project 236") . Project 236 was completed in Factory No. 100 in Chelyabinsk, and was tested successfully from 24 January to 7 February 1943. On 14 February the vehicle was adopted and put into production under the KV-14 (кв-14) designation; in April 1943 the designation was changed to SU-152" (СУ-152). Although the SU-152 was successful in combat, production of the KV-1S tank chassis was ending, which made the modernisation of the vehicle necessary, using the new IS tank chassis. On 25 May 1943 the administration of Factory No. 100 ordered the modernisation of the SU-152, which included increased armour protection and other improvements. Development began in July 1943, under the supervision of Josef Kotin, the chief designer of Soviet heavy tanks, and G. N. Moskvin as the main designer. The new design, designated IS-152 (ИС-152), was tested from September to November 1943. Testing revealed a large number of deficiencies, which sent it back for further improvement. On 6 November 1943 an order was issued for adoption of the improved variant, under the ISU-152 () designation, and in December production began at the Chelyabinsk Kirovsk Plant, replacing the SU-152. Design On 15 April 1942, at the plenum of the artillery committee, where the development of assault guns for support of the infantry was discussed, the necessity of also developing assault guns capable of destroying fortified positions was acknowledged. It was intended these assault guns would be armed with a 152.4 mm gun-howitzer and used for penetration of the enemy defence in the offensive operations planned for 1942–1943. This resulted in the development