It would only be a matter of time before the United States would become involved in the First World War (1917 - 1918). By that time Dr. Ralph Fitch, Orthopedist to Rochester General Hospital was already in France in charge of a French military hospital
In 1915, the Surgeon General, William C. Gorgas asked Dr. John M. Swan to organize a military general hospital for service in Europe in the event that the U.S. entered the war. Swan's organization was the third civilian hospital to be raised and the first not attached to a university. It was activated in February 1918, becoming Base Hospital 19. The hospital's staff was drawn from Rochester's hospitals and Nursing Alumni associations. In July 1918 they were the second medical unit to arrive at the hospital center established in Vichy, France, where they set up a 1,000-bed hospital. Between July 1918 and February 1919 the unit treated 11,000 patients.
At home this cut the hospital's staff by 50%; the complement of six interns was reduced to two, and graduate nurses, orderlies and non-professional staff were called into service. Many doctors came out of retirement; and the Twigs furnished volunteers to help man the hospital during this difficult time. By the end of the war 53 medical staff and former interns and 84 graduates of the School of Nursing had served with Base Hospital 19 and other units at home and abroad.