William Alexander Hammond (28 August 1828 – 5 January 1900) was an American military physician and neurologist.

[3] After his internship and a few months in private practice he became assistant-surgeon in the United States Army, serving from 1849 to 1860.

[6] He conducted research over many years and the resulting paper was awarded a prize by the American Medical Association in 1857.

[7] With a common interest in poisons acting on the nervous system (among them snake venom), he wrote a paper with Silas Weir Mitchell that was published in 1859.

[10] In 1860 he accepted a chair of anatomy and physiology at the University of Maryland School of Medicine in Baltimore and left the army.

When the American Civil War broke out Hammond spent some time at the Baltimore infirmary[11] then joined the army (without recognition of his past service) on 28 May 1861, a month a half after the beginning of the hostilities.

When Finley, the 10th Surgeon General, was fired after an argument with Secretary of War Edwin M. Stanton, Abraham Lincoln, against Stanton's advice and the normal rules of promotion,[12][14] named the 34-year-old Hammond to succeed him with the rank of brigadier general.

[16] He successfully transferred the responsibility for sanitary trains from private companies to the government and personally oversaw the building of the wagons.

Efficiency increased, as Hammond promoted people on the basis of competence, not rank or connections, and his initiatives were positive and timely.

[25] On 4 May 1863 Hammond banned the mercury compound calomel from army supplies, as he believed it to be neither safe nor effective (he was later proved correct).

[2][26] A "Calomel Rebellion" ensued,[27] as many of his colleagues had no alternative treatments and resented the move as an infringement on their liberty of practice.

Hammond's arrogant nature did not help him solve the problem,[28] and his relations with Secretary of War Stanton became strained.

A court-martial found him guilty of "irregularities" in the purchase of medical furniture (Stanton "used false data").

In 1882 he wrote an account of transgender cultural practices among the Pueblo peoples, becoming an early American writer to broach the subject.

[3] He died in Washington on 5 January 1900 of heart failure and was buried with military honors at the Arlington National Cemetery.