After breaking through the Polish line in the Battle of Wizna, the German XIX Army Corps under General Heinz Guderian started its rapid advance south. The corps, composed of the 3rd Panzer Division, the 10th Panzer Division, the 20th Motorized Infantry Division, with the 2nd Motorized Division in reserve, was ordered to capture the old fortress in Brześć Litewski and then strike further southwards towards Kowel and Galicia. The purpose of this attack was to cut Poland in two and paralyze the defenses east of the Bug River.