 Nygren was appointed commanding officer of the 7th Infantry Brigade in 1926 and Commandant in Boden Fortress in 1928.He was promoted to major general in 1929 and was appointed military commander of Upper Norrland's Troops in 1930.Nygren was after that Chief of the General Staff from 1933 to 1937 and acting Chief of the Army from 1936 to 1937 when he was promoted to lieutenant general.