Civil War Union Major General. He was born in Anne's City, Maryland, and graduated 14th in the West Point class of 1831. He was called "Bold Emory" by his classmates, and received the rank of brevet Second Lieutenant in the 4th Artillery. He later would resign his commission after 4 years' service; reenlisting in 1838 as a First Lieutenant in the Topographical Engineers. Over the next several years he developed exceptional skill as a surveyor, notably as second in command during the Northwest boundary dispute from 1844 to 1846. During the Mexican War he served as Lieutenant Colonel of Volunteers, winning 2 brevets for gallant and meritorious service. Until the Civil War he stayed in the Southwest as a surveyor, as commissioner by presidential appointment to establish the Gadsden Purchase boundaries, and as a writer and compiler of maps of the country west of the Mississippi. He was promoted to Captain in April 1851, to Major of the 2nd Cavalry in March 1855, and at the outbreak of the Civil War held rank as Lieutenant Colonel of the 3rd Cavalry. In March 1861 he was sent from Washington D.C., to Fort Smith, Arkansas, with orders to hold Indian territory. Finding the Confederate position too strong, he withdrew the Federal troops to Fort Leavenworth, Kansas, without losing a man in his command. He was commissioned Brigadier General of Volunteers on March 17, 1862. He served under Major General George B. McClellan during the Peninsula Campaign, receiving high praise, and 1 of 4 wartime brevets, for his successful maneuvers to divide the wings of the Confederate army at Hanover Court House on May 27, 1862. Ordered to Louisiana in 1863, he assumed division command under Major General Nathaniel P. Banks and conspicuously led the XIX Corps during the Red River Campaign in 1864. The expedition itself failed, but at the Battle of Mansfield, on April 8, his determined stand inspired Brigadier General Robert A. Cameron's disorganized division to rally long enough to permit an orderly retreat. Later that year he and the XIX Corps were transferred to Major General Philip H. Sheridan's command in the Shenandoah Valley. Though a dedicated and talented soldier repeatedly brevetted in both the volunteer and Regular armies, he did not receive rank as Major General of Volunteers until September 25, 1865. He returned to the Regular Army and successively commanded the Department of West Virginia, the Department of Washington, and the Department of the Gulf before being retired with the rank of Brigadier General on July 1, 1876. In all, he devoted 45 years to the military of the United States.