The Corps was formed for the second time on 18 September 1942 at Kalinin in the Moscow Military District. General Lieutenant M.E. Katukov took command. It was initially assigned to the 22nd Army of the Kalinin Front. It took part in Operation Mars alongside the 22nd Army. At the beginning of Operation Mars 3rd Mechanised Corps consisted of 232 tanks. Hamazasp Babadzhanian, who commanded the 3rd Mechanised Brigade of the corps, mentioned this operation briefly in his memoirs, quoting a conversation with 22nd Army commander, Vasily Yushkevich, who said, “We will conduct a rather serious offensive together with Western Front forces—we must liquidate the enemy Rzhev grouping.”