Finally, the division arrived at the Modlin Fortress, where it received reinforcements and manned the defences of the area. The 32nd Regiment manned the Forts No. 1 and 2, the organic artillery (including the 8th Heavy Artillery Detachment) manned the line east of Kazuń. Overnight of September 7, the 21st Regiment arrived in the area, but was then dispatched further southwards to take part in the battle of Warsaw, while the 13th Regiment under Lt.Col. Alojzy Nowak manned the line along the Vistula near Gniewniewice, west of Modlin. Despite being badly shaken in the first days of the war, the division was successfully reorganized and defended its positions until the capitulation of the Modlin Fortress on September 29.