In June of 1941, Germany's attention turned to their loose ally, the Soviet Union, as Hitler enacted "Operation Barbarossa". Despite warnings from his advisors on the impending invasion, Soviet leader Josef Stalin failed to heed the signs and was taken by surprise as German Army elements - supported by air power - steamrolled the Soviet western frontier. In their wake they left thousands dead and many more captured as well as captured tanks, artillery and small arms. The Germans were supported by Axis allies from Romania, Italy, Hungary, Slovakia, Croatia and Finland.
Progress was initially good until the army was stopped by stretched supply lines, dogged defenses in several key areas and the onset of the Russian Winter. This provided time for the Soviets to rebuilt their losses and relocate fresh troops to the East Front from Siberia. Additionally, Soviet industry was relocated east of Moscow to continue the military build-up. The Soviet response would be swift and terrible, the ultimate undoing of Hitler's grand war scheme, and leas to the fall of his beloved Reich.
During the Soviet response of 1941, there emerged some interim designs quickly fabricated by Soviet industry to help counter the Axis gains. One such development was completed by Gorky Plant No. 92 to which the proven ZiS-2 series anti-tank gun was mated to the chassis of the Komsomolets artillery tractor to create a pseudo-self-propelled gun tracked solution for the Red Army.
The ZiS-2 was developed as recently as 1940 and formally adopted the following year . Of 57mm caliber, the weapon operated from a vertical breech block with limited elevation and traverse but carried strong penetration properties for a weapon of this sort. A trained crew could fire up to 25 rounds per minute out to 5.2 miles and some 10,016 units were ultimately produced.
The Komsomolets T-20 armored tractor was designed in 1936 and entered production in 1937. A crew of two managed its operation which largely revolved around "pack animal" duty in logging various artillery carriages to and fro the battlefield. In military terms, the vehicle was classified as a "prime mover" and designed as a compact though powerful system capable of hauling men and supplies as required. Armor protection was expectedly light and armament was centered on a single 7.62mm DT series machine gun for suppression of enemy infantry. Top speed was 50 kmh with an operational range out to 250 km. Power was served through a 4-cylinder GAZ-M engine of 50 horsepower and operators eventually went on to include Finland, Romania and Nazi Germany herself (captured examples).
Bringing both designs together, Gorky Plant No. 92 produced what became known in the Soviet inventory as the ZiS-30 system. It was classified as a lightweight tracked battlefield system utilizing the lightly armored chassis of the Komsomolets vehicle to which the ZiS-2 anti-tank gun was fitted to a mounting along the rear upper hull. The operating crew was four personnel, two to manage the hull and the other two to manage the gun. A driver was positioned in the armored compartment at the front left with the bow machine gunner to his immediate right - operating the retained 7.62mm machine gun fitting. Armor protection was between 7mm and 10mm across the various angled facings of the armored cab. The gunnery crew sat behind a thin shield to either side of the gun breech, exposed to the elements. The tracked nature of the ZiS-30 gave it adequate cross-country capabilities and the 57mm anti-tank gun allowed it penetration capabilities against the latest German armor at range.
Despite the logistically friendly conversion process, the ZiS-30 was produced in relatively few numbers owing to the limited surplus of available Komsomolet tractors as well as the ZiS-2 series guns - both of which were needed elsewhere in the war effort. As such, the ZiS-30 led a short operational service life before being quickly replaced by more capable artillery types soon to emerge from Soviet factories. At any rate, the ZiS-30 was a commendable design and an approach dictated by war needs, certainly comparable to similar German developments in mating existing guns to outdate French tractors (as in the Marder series).