William Hammond was born in Maryland in 1828 and received a degree in Medicine from the University of the City of New York in 1848. After a brief stint in the Army, he joined the University of Maryland as Professor of Anatomy and Physiology. However, after he came into contact with some of the wounded soldiers in the Baltimore Infirmary he decided to rejoin the Army as Assistant Surgeon. His initial duties included purchasing supplies, organizing hospitals and inspecting field camps.
His organizational ability was such that he attracted the attention of the U.S. Sanitary Commission, which recommended that he be appointed Surgeon General. He took up the post in April 1862 and immediately undertook a reorganization of the medical department. At the same time he established the Army Medical Museum and the principles of accumulating and recording data on battlefield wounds and disease for the purpose of learning from the experience of war.
Despite his successes, Hammond was not supported by the Secretary of War, Edwin Stanton, and he was relieved of his post in 1864, following a trial by court martial in which he was found guilty of medical supply purchasing "irregularities". He subsequently became Professor of Nervous and Mental Disease at the Bellevue Medical Hospital and (in 1874) at the University of the City of New York. In 1878, he was exonerated by the United States Congress and was officially reinstated in the Army. He died in Washington, D. C. in 1900.