William Hemsley Emory, United States Army officer and boundary surveyor of Texas, son of Thomas and Anna Maria (Hemsley) Emory, was born at Poplar Grove estate in Queen Anne's County, Maryland, on September 7, 1811. He attended the United States Military Academy, West Point, New York, and graduated in 1831. He resigned from the army in 1836 to work as a civil engineer but returned to the service in 1838. That year he married the great-granddaughter of Benjamin Franklin, Matilda Wilkins Bache of Philadelphia; they had three children. In the coming years, as a lieutenant, captain, and major in the topographical engineers, Emory specialized in exploration and conducting boundary surveys along the Texas-Mexican border (1844), the United States-Canadian border (1844–46), the United States-Mexican border (1848–53), and the Gadsden Purchase (1854–57).
In 1844 Emory served on an expedition that produced a new map of Texas showing Texas claims westward to the Rio Grande. He came to public attention as the author of Notes of a Military Reconnaissance from Fort Leavenworth in Missouri to San Diego in California, published by the Thirtieth Congress in 1848. This report described terrain and rivers, cities and forts, pueblos and prehistoric ruins, animals and plants, and Indians and Mexicans, primarily in New Mexico, Arizona, and Southern California. It was then and later considered one of the important chronicles and descriptions of the Southwest, especially for its maps. Emory was a reliable cartographer and drew dozens of maps of the West. His accurate rendering of the topography usually made other maps obsolete. He acquired his greatest fame as supervisor of the United States-Mexican boundary survey between 1848 and 1853. That survey included an exploration of the Big Bend region of the Rio Grande River. Emory's maps and reports made him the foremost authority of the trans-Mississippi Southwest in the United States.
During the Mexican War (1846–48), Emory served in the Southwest and in California as chief engineer in the Army of the West under Gen. Stephen W. Kearny. At the outbreak of the Civil War in 1861 he was stationed with soldiers in Indian Territory and withdrew forces under his command to Fort Leavenworth. He served as a brigade commander in the Union's Army of the Potomac (1862). After transfer to the Western Theater, he commanded a division in the Port Hudson campaign and the Red River campaign in Louisiana (1863–64). He subsequently returned to the East as commander of the Nineteenth Corps, which performed badly in the Shenandoah Valley (1864), especially at the battle of Cedar Creek, where Emory was rescued by Gen. Philip Sheridan's arrival.
After the war Emory held a number of posts, most importantly commander of the Department of the Gulf (which included soldiers in Louisiana, Arkansas, and Mississippi)-a demanding and dangerous Reconstruction assignment. General Sheridan removed Emory from command and saw to it that he was retired in 1876. The Department of the Gulf was soon shifted to Sheridan's large Division of the Missouri, which included Texas. Emory died on December 1, 1887, in Washington, D.C.