From 1922 to 1926, Jung served in the War History Department of the General Staff, after which he was a teacher in war history and strategy at the Royal Swedish Army Staff College from 1926 to 1928. He was promoted to Major in 1928, after which he was acting head of the War History Department in the General Staff from 1928 to 1929 and regular head of the same from 1929 to 1933. He was secretary of the issues regarding the Swedish Army in the 1930 Defence Commission from 1930 to 1935. In 1933 he was promoted to Lieutenant Colonel, after which he was head of the Foreign Affairs Department in the General Staff from 1933 to 1936. He was secretary of the Committee on Defence during the Riksdag of 1936.