With the latter, he served as a Red Army man before graduating from the divisional school in 1920 to become a platoon commander. Monakhov fought in battles against the Armed Forces of South Russia in Right-bank Ukraine, the disarmament of the Revolutionary Insurrectionary Army of Ukraine in the Alexandrovsk area, and in the Odessa Operation. In spring and summer 1920 he fought in the Polish–Soviet War in the advance on Kiev, Shepetovka, and Lvov. In November he fought with the division in the elimination of the Ukrainian People's Army and remnants of the Army of Wrangel in western Ukraine, after which the division suppressed anti-Soviet forces in Ukraine.