Edward Otho Cresap Ord, United States Army officer and designer of Fort Sam Houston, the third son of James and Rebecca Ruth (Cresap) Ord, was born in Cumberland, Maryland, on October 18, 1818. His father was a United States naval officer, and his mother was the daughter of Daniel Cresap, an officer in the American Revolution. The family moved when Ord was a year old to Washington, D.C., where he received his early schooling. He was appointed to the United States Military Academy at West Point in September 1835 at the age of sixteen. After graduating seventeenth in the class of 1839, he was commissioned as a second lieutenant in the Third Artillery Regiment and after field service against the Florida Seminoles was promoted to first lieutenant two years later. During the Mexican War he was stationed in California. In 1850 he was promoted to captain on Indian duty in the Pacific Northwest. He participated in the suppression of the John Brown insurrection at Harpers Ferry in 1859 but was back in California, stationed at the Presidio, at the time of the firing on Fort Sumter.
He received a commission as brigadier general of volunteers on September 14, 1861, and during the first year of the Civil War commanded a brigade assigned to defend the capital. Ord participated in a skirmish with Jeb Stuart's cavalry at Dranesville, Virginia, on December 20, 1861, was promoted to major general of volunteers on May 2, 1862, and was transferred to the western theater of operations. Although he was not even within the sound of the guns at the battle of Iuka, Mississippi, on September 19, 1862, he was given a colonel's brevet in the regular army "for gallant and meritorious service" on the field. He was severely wounded a few days later at Hatchie, Mississippi, and was incapacitated until June 1863, when he returned to the army in time to take part in the siege of Vicksburg as commander of the Thirteenth Corps. After the fall of Vicksburg on July 4, Ord held commands in Louisiana and in the Shenandoah Valley of Virginia. During the siege of Richmond he commanded first the Eighth Corps and later the Eighteenth Corps. He was again seriously wounded at the storming of Fort Harrison in September 1864 and did not return to his command until January 1865. On March 13, 1865, he was awarded the brevet rank of brigadier general for his role in the battle of Hatchie, Mississippi, and a major general's brevet for his part in the assault on Fort Harrison, Virginia. He was then given command of the Army of the James with responsibility for the Department of North Carolina.
Ord became a brigadier general in the regular United States Army on July 26, 1866. After the surrender of the Confederate armies, he first commanded the Fourth Military District and then the military departments of California and the Platte before receiving assignment to command the Military Department of Texas on April 11, 1875. He supervised the construction of Fort Sam Houston. His command numbered from 3,000 to 3,900 troops, stationed at San Antonio and forts Brown, Concho, Clark, Davis, Duncan, McKavett, and Ringgold. From his headquarters at San Antonio Ord oversaw the scouting, construction of telegraph lines, and post maintenance and repair, as well as suppression of cattle rustling and hostile Indians. Troops under Ord's command were responsible for the discovery of grazing land in the state's trans-Pecos region as well as deposits of silver, iron, lead, and copper.
Ord was married to Mary Mercer Thompson at San Francisco on October 14, 1854. The couple had thirteen children. He retired from active duty on December 6, 1880, with the rank of major general. He was stricken with yellow fever on a cruise ship bound from New York to Veracruz and died in Havana on July 22, 1883. He was buried at Arlington National Cemetery.