After the end of the Greater Poland Uprising the regiment was reformed, reinforced with HMGs and partially demobilized. It took part in taking over the town of Wieleń from the German administration on January 17, 1920. Again renamed, this time to "1st Reserve Regiment", it was included in the Polish Army and sent to the front of the Polish-Bolshevik War. Almost annihilated during the Battle of Grodno, it was reinforced by Lt. Lisewski it again entered combat during the Battle of the Niemen River, after which it was withdrawn to the training ground in Biedrusko. After the cease-fire and signing of the Riga peace treaty, the regiment was moved to Lubliniec on June 26, 1922.