an S-1 76.2 mm tank gun (a cheaper variant of the renowned F-34/ZIS-5 guns which were already mounted on T-34 and KV-1 tanks respectively) in a casemate superstructure but retained the original German Maybach gasoline engine and its torsion-bar suspension system. Around 200 of these ex-German vehicles were sent for conversion into SU-76is at Factory No. 37 to supplement the existing SU-76. They were issued to tank and self-propelled gun units starting in the fall of 1943. They were eventually withdrawn from the front in early 1944 and then used for training and testing until the end of 1945. Only 2 have survived the war, most having been scrapped after 1945. A similar vehicle called SG-122 existed, which was a similar Panzer III conversion, but armed with 122 mm M-30 howitzer. Only around 20 were converted, as the M-30 was considered an insufficient weapon for infantry support. The also unrelated SU-76P (1941) was based on the T-26 chassis. It was built in Leningrad during the Siege of Leningrad and involved removing the turret from the T-26 and mounting a 76 mm regimental gun M1927 on the engine deck. This was created due to the lack of high-explosive 45 mm ammunition inside Leningrad due to the siege, so some T-26 tanks were rearmed with 37mm or 76mm guns for which a reliable source of ammunition was available. They served until 1944, when the siege was broken. They were originally called "SU-76s", until the SU-76 came into service, upon which it was renamed "SU-76P" ("polkovaya" - regimental). Combat history The SU-76M virtually replaced infantry tanks in the close support role. While its thin armour and open top made it vulnerable to antitank weapons, grenades, and small arms, its light weight and low ground pressure gave it good mobility. The SU-76M combined three main battlefield roles: light assault gun, mobile anti-tank weapon and mobile gun for indirect fire. As a light assault gun, the SU-76M was well-regarded by Soviet infantrymen (in contrast with their own crews). It had more powerful weapons than any previous light tank for close support and communication between infantry and the SU-76M crew was simple due to the open crew compartment. This was extremely useful in urban combat where good teamwork between infantry and AFVs was a key to success. Although the open compartment was highly vulnerable to small arms fire and hand grenades, it very often saved the