During the 1939 Invasion of Poland he served as a quartermaster of the 33rd Infantry Division. Taken prisoner by the Soviets in early October, he managed to escape and returned to his native Vilna, where he soon joined the Polish underground: the Service for Poland's Victory, the Union of Armed Struggle and finally the Home Army. He took part in the Operation Ostra Brama as commanding officer of the East group attacking the city of Vilna from the direction of Nowa Wilejka and Belmont.