War had resumed in September 1939 following a Nazi-Soviet Non-aggression pact that opened the way for a repeat partition of Poland between the two dictatorships. It ended in May 1945 with the central part of what had been Germany, including Thuringia, under Soviet Military Administration. In 1945 Jung became a member of the Communist Party regional leadership team in Erfurt. Between June and September 1946 he was employed as the manager at the Employment Office in Waltershausen: then from October 1945 till January 1946 he served as deputy administrator ("Landrat") in Gotha. Between February 1946 and October 1948 he served in Weimar-Erfurt as First Secretary of the People's Solidarity organisation, a non-parliamentary Mass movement after the Leninist model, focused in this instance on funding and administering care for the elderly.