Remembering World War I: American Medical Units Mobilize Shortly after U.S. Enters the War
Less than a month after the United States entered World War I, Maj. Harry L. Gilchrist with the U.S. Army Medical Corps received orders to move Base Hospital No. 4 to France. On May 8, 1917 the unit departed New York harbor for Europe, and within weeks it had replaced a British hospital and was receiving patients in Rouen, France. Base Hospital No. 4 was one of six mobilized immediately to assist the British Expeditionary Force in France.
While General of Armies John J. Pershing had not yet set foot in France, British forces could not delay in making an urgent plea for medical support. In total they requested sixteen base hospitals and additional medical staff to assist their forces. Because the British had been fighting for nearly three years, they were in desperate need of fresh staff and support. Fortunately, advanced preparation of the American Red Cross (ARC), the Army, and Allied transportation made an immediate response possible.
The Army had established reserves of medical supplies for 67 field, base, and evacuation hospitals, 41 ambulance companies, and 131 combat regiments. These supplies were distributed from medical depots around the United States, and coordinated by an established system of telegraph communication. Even though the United States had never fought in this type of global conflict, the country managed to mobilize resources in an efficient and quick manner based on the realities of the early 20th century.
The Army Nurse Corps, established in 1901, was supplemented by the ARC nursing reserve with around 8,000 trained nurses ready for overseas assignments. The ARC had been providing services in Europe since fall 1914. It worked closely with the Army and Navy, and other private American medical agencies, and it raised funds, trained reserve staff, and acquired supplies and equipment.
The Army Medical Corps had sent American medical observer missions to France, Britain, and Austria-Hungary in 1915. They learned vital practical lessons for Army medical and ARC staff preparing for war. Before April 1917 some American military medical staff resigned their commissions to work as civilian volunteers with ARC, French, and British medical services in Europe. Later their experience made it possible for the Army Medical Corps to combine efforts with the Allied medical organizations. Col. Alfred Bradley, who served as a medical observer in Britain beginning in 1916, became American Expeditionary Forces Chief Surgeon. Before the end of 1917 he would be supervising the six mobilized reserve base hospitals.
Gen. Pershing arrived in France at Boulogne on June 13, 1917, and members of the American Infantry, in their broad-brimmed campaign hats, arrived at St. Nazaire on June 26. By that time, U.S. Army Base Hospital No. 4 was already treating the sick and wounded at Rouen, providing some of the first, on-the-ground support to Allied forces.
 Sanford H. Wadhams and Arnold D. Tuttle, "Some of the Early Problems of the Medical Department, AE.F.,"Military Surgeon 45 (December, 1919), 637.
 Jonathan Hunter, Medical Support for the American Expeditionary Forces in France During the First World War (Thesis), Ft. Leavenworth , Army Command and General Staff College. 1991 pp. 1-2, & 32
 Ibid. p. 19
 Ibid. p. 15