Jung was chief of the Military Office of the Land Defense ("Lantförsvarets kommandoexpedition") from 1936 to 1937, colonel and executive officer of the Life Regiment Grenadiers (I 3) in 1936 and colonel and Chief of the Army Staff and the General Staff Corps from 1937 to 1940. He became major general of the army in 1938 and was commanding officer of the II Army Division from 1940 to 1942. Jung was then the military commander of the II Military District in 1942 and commanding officer of the IV Military District and was the Commandant General in Stockholm in 1943. He was appointed lieutenant general in 1944 and general in 1944. Jung was the Supreme Commander from 1944 to 1951.