During the revolution he traveled to Minsk, where he got to know the criminal underworld. In Minsk he joined troops fighting for Belarusian independence. Those were soon defeated, and Piasecki himself got wounded. After that he joined the Polish 1st Lithuanian–Belarusian Division which at this time had taken over Minsk and was heading east with offensive (see: Polish–Soviet War); he took part in Battle of Warsaw (1920).