The battle of Tomaszów Mazowiecki was fought on 6 September 1939 near the town of Tomaszów Mazowiecki, Second Polish Republic, during the invasion of Poland. The area was defended by Polish 13th Infantry Division under Col. Władysław Kaliński, and Germany's assault was carried by two armored divisions of the 16th Panzer Corps. After the day-long battle, German forces broke through the Polish defences and took the town. The Polish 13th Division sustained heavy losses and was forced to retreat towards Warsaw.