Stefan Dąb-Biernacki Army Łódź: Army Prusy: XVI Panzer Corps: Baltic coast 4–10 September Northern Front Southern Front The Battle of Piotrków Trybunalski was a battle in the German Invasion of Poland from 4 to 6 September 1939, which involved Polish and German tank formations.

The army, created as the main operational reserve of Polish commander in chief Marshall Edward Rydz-Śmigły, was also the last to be mobilised in the summer of 1939.

By 4 September 1939, when the German forces broke through the overstretched Polish defences, the Prusy army was far from battle-ready.

[1]: 60 On the morning of 4 September, Hoepner’s XVI Panzer Corps reached Rozprza, just 12km south of Piotrków.

It was a defensive position of the "Lodz" army under command of general Thommee, defended by an improvised infantry battalion without anti-tank weapons, supported by two artillery pieces.

At the same time, Hopener decided to regroup his 1st and 4th panzer divisions, and attack Piotrków next day using the captured bridgeheads.

At the same time, Biernacki, unaware of the loss of the city due to missing reports, continued to prepare for a night attack.