William Hemsley Emory was born in Queen Anne's County, Maryland in 1811. He was a graduate of the United States Military Academy in 1831, and served his country as a soldier for more than four decades. During the Mexican War he served as Lieut. Colonel, Regiment of Maryland and District of Columbia Volunteers.

During the Civil War he served in a variety of capacities and numerous campaigns including: in the defense of Washington, 1861 to 1862; in the Virginia Peninsular Campaign (Army of the Potomac), Mar.-Aug. 1862; being engaged in the Siege of Yorktown, Battle of Williamsburg, Hanover Court House in 1862; in the Department of the Gulf, Dec. 1862 to July 1863. In 1864 he was transferred with 19th Army Corps to the defense of Washington, D.C., including service in the Shenandoah Campaign.

Ultimately, however, his reputation rests less on his ability as a fighting officer who inspired his troops by example, but rather more on his outstanding work as a scientist and scholar. Trained as an engineer at West Point, Emory meticulously recorded his explorations of the American Southwest during the 1840s and 1850s. The subsequent publications of his findings earned him the applause of both amateur and professional scientists and made him the authority on this region of the United States.