first lieutenant and served again as a flying instructor, at Galveston, Texas, and San Diego. In August 1914, Milling accompanied the U.S. Relief Commission to Europe to assist in the repatriation of Americans stranded in war-torn Europe. In March 1916, he was again detailed to the Office of the Chief Signal Officer and promoted twice (to captain July 31, 1916, and to lieutenant colonel August 5, 1917). In August 1917, he was placed in charge of Air Service Training in Europe, and in October 1918 succeeded Billy Mitchell as chief of the Air Service of the U.S. First Army, American Expeditionary Force, and promoted to colonel. Milling returned from France in January 1919 and served in a variety of assignments for the next seven years: assistant chief, Training and Operations Group, including president of a board to determine all aerial laws, rules and regulations, (January 1919 to June 1920); officer in charge, Air Service Field Officers' School, Langley Field, Virginia (July 1920 to June 1922); assistant commandant, Air Service Tactical School, Langley Field (June 1922 to January 1925); operations officer, Second Bombardment Wing, Langley Field (January to June 1925); and Air Service Engineering School, McCook Field, Dayton, Ohio, completing the course in August 1926. Milling then attended the Command and General Staff School at Fort Leavenworth. Graduating in June 1927, he was assigned to the War Plans Section, Office of Chief of the Air Corps in Washington, D.C., where his duties were mainly administrative in connection with war planning and legislation. In June 1930, Milling was sent to the Colorado National Guard in Denver, Colorado to serve as an Air Corps instructor. In September 1931, he served briefly at Rockwell Air Depot, California, then was admitted to Fitzsimons General Hospital in Aurora, Colorado, where he was a patient from October 1931 to July 31, 1933, when he retired from active duty due to poor health. World War II service During World War II, Milling was recalled to active duty as a major on March 16, 1942, to serve on the War Department Decorations Board in Washington, D.C., and was promoted to lieutenant colonel April 27, 1942, and to colonel September 24, 1942. In December 1942, he served as the air representative on the United States Congress Joint Intelligence Sub-Committee and later was a member of the Joint Intelligence Staff in the office of the Assistant Chief of Staff, Intelligence, until