The first recorded combat deployment of armored walkers occured on the Eastern Front, where the Kampfläufer series made their debut in German service. Originally developed for use in urban combat, the Kampfläufers were used successfully in the breakout of the encircled 6th Army from Stalingrad in Operation Winter Storm, though not without cost.
Due to the unpredictability of close-quarters combat, the initial unreliability of the Ausf. A-series models, and the inexperience of the first generation of läufer pilots, many Kampfläufers were lost in the savage fighting within and around Stalingrad.
Subsequently, the Soviets captured a number of specimens in varying states of operability. However, because of the Soviet 62nd Army’s preoccupation with regaining the initiative on the Eastern Front following the battle, Marshal Vasily I. Chuikov sent examples of the Kampfläufers over to the United States for study and reverse-engineering.
Following a period of research into the joint and leg structure of the captured Kampfläufers, the US Army was able to develop a sort of “walker conversion kit” for their tanks. This consisted of a power pack with a new high-powered X12 engine and accompanying transmission, as well as a pair of armored hydraulic leg units. The American X12 engine was an imitation of the advanced X20 engine used in Germany’s Kampfläufers, though in effect it was more akin to a pair of stacked V6 engines. Nevertheless, it would be America’s primary light tank at the time, the M5 Stuart, that was selected as the first tank for conversion into a walker.
Referred to as the “Mech5 Stuart“, this walker would be available in limited numbers for use in “experimental battalions” that would participate in the Allied advance in Italy following the Invasion of Sicily. A small production batch of converted Mech5 Stuarts would also be exported back to the Soviet Union as a “thank you” gift for their shipping of the original Kampfläufer samples to the USA for study. It would be these simplified American-made walkers that would inspire the Soviets to develop their own walkers for use in later counteroffensives on the Eastern Front.