During the invasion of Poland in 1939, General Biernacki commanded the Army "Prusy", which was supposed to be the strategic reserve that would be used to launch a concentrated counter-attack as the enemy approached Warsaw. However, Army "Prusy" was far from concentrated or ready for action on 1 September.[1] He was actually commanded a part of the army consisted of 3 infantry divisions (19, 29, 13) and one cavalry brigade (Wileńska Cavalry Brigade). He made an attempt to stop the German XVI Army Corps who had broken through the front near Częstochowa and pushed towards Warsaw. After Battle of Piotrków and Battle of Tomaszów Mazowiecki his forces were broken and scattered, and he gave the orders to retreat to the right bank of the Vistula river. On 10 September he become commander of Northern Front, consisted of remaining fragments of Polish Army. After his defeat at Battle of Tomaszów Lubelski, he managed to evacuate to France through Hungary, where he was immediately arrested by order of the Commander-in-Chief General Wladyslaw Sikorski for political reasons. In October 1940 he was sentenced to two and a half years in prison and demotion to the rank of private for "breaking military discipline and attempting to cause ferment in the ranks of soldiers". In November 1940 he was discharged from the army. When General Kazimierz Sosnkowski took over the position of Commander-in-Chief in 1943, Dąb-Biernacki was released from prison and went to Ireland, where he was engaged in beekeeping.
Honours and awards
Knight's Cross of the Order of Virtuti Militari (previously awarded the Gold Cross and Silver Cross)
