William Willis Blackford was born on March 23, 1831, in Fredericksburg, the second of six sons and third of eight children of William Mathews Blackford and Mary Berkeley Minor Blackford. At age eleven he accompanied his father to Bogotá, New Granada, where his father served for three years as chargé d’affaires. Blackford learned Spanish in Bogotá and excelled in horsemanship. The year after he and his father returned to Virginia in 1845, the family moved to Lynchburg. Blackford continued his education and then worked on railroad construction survey crews for three years, saving enough money to study engineering at the University of Virginia for the academic year 1849–1850.
Blackford worked as a civil engineer during the construction of the Virginia and Tennessee Railroad and was acting chief engineer when the road was completed. On January 10, 1856, he married Mary Trigg Robertson, of Richmond. Of their four daughters and three sons, two daughters and one son died in infancy. Between his marriage and the outbreak of the Civil War, Blackford and his wife moved to Washington County, where he became a partner with his father-in-law, former governor Wyndham Robertson, in a gypsum-mining operation near Abingdon.
Following‘s raid on in October 1859, Blackford organized the Washington Mounted Rifles as part of the county militia and was elected lieutenant. Although opposed to , he led his company into Confederate service in July 1861 as part of the 1st Virginia Cavalry, under the command of Lieutenant Colonel James Ewell Brown Stuart. Blackford served as Stuart’s aide-de-camp and on October 3, 1861, was promoted to captain. In May and June 1862 Blackford was detached to supervise construction of pontoon bridges across the , but he rejoined the cavalry before the Seven Days’ Battles and rode with Stuart’s cavalry in every major engagement of the war except (1863). One of Stuart’s best officers, he was wounded twice and had at least three horses killed under him. On January 19, 1864, Blackford was promoted to major of engineers, and on April 1 he was promoted to lieutenant colonel and sent to , where, during the of the city, he supervised the digging of shafts and tunnels to detect Union attempts to place subterranean mines under Confederate emplacements. (Union forces succeeded in detonating one such mine in July 1864, leading to the .) Blackford at Appomattox Court House on April 9, 1865.
After the Civil War ended Blackford worked as chief engineer for the Lynchburg and Danville Railroad. His wife died in 1866, after which he and his children moved to Terrebonne Parish, Louisiana, where he operated a sugar plantation that his father-in-law had given him. A flood in 1874 destroyed much of the property, and Blackford returned to Virginia. From 1880 to 1882 he was professor of mechanics and drawing at the Virginia Agricultural and Mechanical College (later Virginia Polytechnic Institute and State University) at Blacksburg, and he also served as superintendent of grounds and buildings and landscaped the campus. Between 1882 and 1890 Blackford worked as a construction engineer for the Baltimore and Ohio Railroad on its line between Baltimore and Philadelphia and on the construction of a railroad between Lynchburg and Durham, North Carolina. Blackford then retired and moved to Princess Anne County.
A number of Blackford’s Civil War letters appeared in Susan Leigh Colston Blackford’s Memoirs of Life In and Out of the Army in Virginia During the War Between the States (1894–1896; reprinted 1996 and in abridgement as Letters from Lee’s Army, 1947). Douglas Southall Freeman and other historians have found the volume useful. Blackford also composed an account of his Civil War experiences early in the 1890s. It was published as War Years with Jeb Stuart (1946), with an introduction by Freeman. The direct and unembellished style, interesting anecdotes, and vivid descriptions of battlefield scenes make it an outstanding memoir of a Confederate cavalry officer.
During his last two years Blackford worked with the United States Department of Fisheries unsuccessfully experimenting with means of artificially fattening oysters. Blackford died of apoplexy at his home in Princess Anne County on May 1, 1905, and was buried in Sinking Spring Cemetery in Abingdon.
- War Years with Jeb Stuart (1946)