It was during the American Civil War that Surgeon (Major) Jonathan Letterman, Medical Director of the Army of the Potomac, realised a need for an integrated medical treatment and evacuation system. He saw the need to equip this system with its own dedicated vehicles, organisations, facilities, and personnel. The Letterman plan was first implemented in September 1862 at the Battle of Antietam, Maryland. The United States Army’s need for medical and scientific speciality officers to support combat operations resulted in the creation of two temporary components: the US Army Ambulance Service, established on June 23, 1917 and the Sanitary Corps, established on June 30, 1917. Officers of the Sanitary Corps served in medical logistics, hospital administration, patient administration, resource management, x-ray, laboratory engineering, physical reconstruction, gas defence, and venereal disease control. They were dedicated members of the medical team that enabled American generals to concentrate on enemy threats rather than epidemic threats. On August 4, 1947, Congress created the Medical Service Corps.