 From March 1932 to September 1935 he commanded the 5th Legions' Infantry Regiment ("5 Pułk Piechoty Legionów") in Wilno (it was part of the elite 1st Legions Infantry Division), then returned to again head Section II.As chief of the Second Department of Polish General Staff, Pełczyński, like his predecessor Colonel Tadeusz Schaetzel and like deputy chief Lt. Col. Józef Englicht, was very supportive of Marshal Józef Piłsudski's Promethean project, aimed at liberating the non-Russian peoples of the Soviet Union.Pełczyński was the longest-serving prewar chief of the Second Department (1929–32, and 1935 – January 1939).