After the cease-fire and the Treaty of Riga, the division was partially demobilized and its regiments were stationed in a number of Mazovian towns, including Modlin, Pułtusk, Warsaw, Działdowo and Płock.
As the Mazowiecka Cavalry Brigade operating further eastwards was also endangered by German armoured troops, the army commander ordered the division to split its forces and attack in two directions: towards Grudusk east of Mława and towards Przasnysz.
However, conflicting orders and German saboteurs operating in the rear disrupted both attacks and led to chaos in the Polish ranks.
In the evening, the division was mostly dispersed and only the 21st Infantry Regiment of Colonel (later General) Stanisław Sosabowski managed to withdraw from the fights towards the Modlin Fortress.
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.
The new unit, formed primarily of Polish soldiers previously held in Soviet Gulags, was commanded by Col. Bronisław Rakowski and received the name of 8th Infantry Division.
After the Soviet take-over of much of Poland in 1944, the Communist authorities started to form the 8th Division of the Polish People's Army in the area of Siedlce.
On April 15, it was attached to the Polish 2nd Army and the following day it entered combat in the area of the Lausitzer Neisse river during the Battle of Dresden.
After crossing the river, the division - deprived of artillery and air cover - took part in the heavy fighting for Nieder Neudorf and the village of Biehain.
On April 17, aided by the badly beaten Polish 16th Armoured Brigade, the division continued its assault on Ober and Mittel Horka defended by the elite Brandenburger Regiment.
After the initial failure, the division managed to break the German resistance in an all-out assault and reached the Weisser Schops River, which it crossed under heavy enemy fire.