On September 5 the Brigade defended the line of the Warta river, near Sieradz. Threatened with encirclement, it withdrew eastwards, crossing the Ner to the area of Zgierz. On September 8, as a result of German attacks, it dispersed. Remnants crossed the Vistula on September 10 and joined the Northern Front of General Stefan Dąb-Biernacki, fighting in the Battle of Tomaszów Lubelski. Last units of the Brigade capitulated on September 26, after skirmishes in the area of Sadowa Wisznia.