On 15 September the unit was yet again advancing in pursuit of the withdrawing Red Army. That day the unit captured Kamień Koszyrski, where it took more than 1000 prisoners of war and the matériel depot of an entire division. During the Battle of the Niemen River Bałachowicz's unit prevented the enemy from forming a defensive line in Polesie. Overnight of 21 September his unit outflanked and then destroyed completely the Bolshevik 88th Rifle Regiment near the town of Lubieszów. Perhaps the most notable victory of the Bułak-Bałachowicz's Group took place on 26 September, when his forces took Pinsk in the rear. The city was the most important rail road junction in the area and was planned as the last stand of the Bolshevik forces still fighting to the west of that city. According to a book published in 1943, after Bułak-Bałachowicz's troops entered Pinsk, they may have committed a series of pogroms on the Jewish population. There were hundreds of victims of rape and murder in Pinsk and in the vicinity around that time, although none specifically linked to Bułak-Bałachowicz.