Meshcheryakov joined the Red Army in March 1918 after a Red Guard detachment was formed from former soldiers of the Imperial Army. Between April and August, he was assistant commander of a machine gun company in the Communist Special Purpose Regiment after the detachment was merged. In July, Meshcheryakov participated in the suppression of the Left SR uprising in Moscow. Between 1918 and 1919, he was a machine gun instructor at the 3rd Moscow Command Courses, staffed by former non-commissioned officers of the Imperial Army. In 1919, Meshcheryakov fought in the Defense of Petrograd with the Consolidated Moscow Cadet Brigade against White general Nikolai Yudenich, and in the elimination of Lieutenant General Viktor Pokrovsky's White partisans in the Caucasus in early 1920, after the courses were relocated to Maykop.