US Army Ambulance Service (USAAS) patch

At the outbreak of World War I, the American Field Service was organized by Americans who were living in Paris. They volunteered themselves to be ambulance drivers and medical staff for the French and British Armies. The United States had not yet entered WWI and the U.S. Army did not have an ambulance service, so these volunteers fell under the jurisdiction of the French government. When the United States entered the war, it was quite evident that there was a great need for an ambulance service during combat. At the request of the French government for the United States to continue to provide ambulance and medical services to the French Army, the U.S. Army established the U.S. Army Ambulance Service in May 1917 as a new organization in the Army’s Medical Department.