William H. Leininger (1894 - 1991) enlisted in the Air Service at Ft. Sill on June 4, 1917. Leininger was the Post Sergeant of the 21st Squadron until his transfer to the Cadet School at the University of Illinois. After graduating from Cadet School, Leininger was first transferred to Kelly Field for flying instructions and then to the 3rd Aviation Training Center at Issoudun, France. Leininger was ordered to the Front with the 9th Aero Squadron where he performed both day and night reconnaissance flights. After the Armistice, Leininger was assigned Squadron Leader for the 166th. In 1919, he was relieved of that command and returned to the United States. After the war, Leininger remained interested in aviation matters, but he did not pursue work in the aviation field.