In 1911, he had accepted a commission as a First Lieutenant in the United States Army Medical reserve Corps. This eventually led to his taking a leave of absence from the University in February 1915 to serve at the American Ambulance Hospital outside Paris. Sutton and others from his days at Columbia and Roosevelt arrived at College of Juilly on February 23 where hospital facilities had been set up only 40 miles from the front lines of World War I. Within 2 months, he was surgeon-in-chief handling administrative duties in addition to his surgical responsibilities. His inventive aptitude was perhaps never more valued as he developed fluoroscopic techniques to identify and localize shrapnel within the soldier's bodies and then removed the foreign items with instruments of his own design. After his return, he documented these techniques in Binnie's Manual of Operative Surgery. Sutton's return sailing from France was on June 26, 1915 having stayed only four months, but have made a significant contribution to wartime medical treatment.