 In January 1939 he was relieved of this post and placed in command of the 19th Infantry Division ("19 Dywizja Piechoty"), stationed in Wilno.His tenure as chief of Section II had reportedly been ended by his wife Wanda's political activities against Marshal Edward Śmigły-Rydz and General Felicjan Sławoj-Składkowski.Pełczyński may have made his greatest contribution to Allied victory in World War II well before the opening of hostilities, when he proposed giving Polish knowledge of the German Enigma machine to the French and British.