Saunders Fleming served in the U.S. Army as a First Lieutenant in the 317th Infantry Regiment, 159th Infantry Brigade, 80th ("Blue Ridge") Division, American Expeditionary Force during World War I. He fought in a number of battles in France and was in the Bois de Moriaux, South of Villones, when, while cleaning his pistol, he shot himself. He died from his wounds on October 23, 1918. He is buried in the Meuse-Argonne American Cemetery, Lorraine, France.
