The Medical Director of the Army of the Potomac, Dr. Jonathan Letterman, organized the Army into a system of Divisional hospitals in October 1862. This system of organization and management eventually spread throughout the Federal Army.
Commanded by one medical officer rather than a line officer, it consisted of four operating teams of three surgeons each and numerous medical attendants and support staff. Each hospital carried sufficient medical supplies to house and care for a typical division of 7,000-8,000 personnel. Division surgeons performed more thorough examinations and treatment of wounds and emergency surgeries. A large portion of surgeries were postponed until reaching the much larger Depot evacuation hospitals. At the end of the day’s campaigning, each division hospital set up what was referred to as a “Ambulance hospital” that treated minor wounds and common illness’ such as sunstroke and diarrhea. Division hospitals were organized into centrally located Corps Hospitals consisting of three to four divisions.