Duval was born and raised in Wellsburg, West Virginia (then Virginia) in Brooke County. He attended the common schools as a child. As a young man, he traveled to Fort Smith, Arkansas, where he joined an elder brother who was running a trading post. Afterward, he became a scout on the Western Plains and Rocky Mountains, and joined the Gold Rush in 1849.

He was a member of the Lopez expedition to Cuba that sought to aid the Cuban national independence movement. After his time as a filibuster, he returned to Wellsburg in 1853 and worked as a merchant.

During the Civil War, Duval was commissioned as the first major of the 1st Virginia Volunteer Infantry on June 1, 1861. He was later promoted to colonel of the 9th West Virginia Volunteer Infantry. In September 1864, he was badly wounded in his thigh at the Battle of Opequon. After he recovered, he was promoted to the rank of brigadier general and given charge of a brigade of infantry in the VIII Corps.

By the end of the war, Duval had fought in 36 separate engagements and commanded two different divisions in the VIII Corps. He had eleven horses killed and wounded under him. On May 17, 1865, after the surrender of the main Confederate armies under Generals Lee and Johnston, but with some other Confederate units still in the field in the west, an unknown attacker tried to kill Duval at Staunton, Virginia.^[1] Duval was mustered out of the volunteer service on January 15, 1866.^[1] On February 24, 1866, President Andrew Johnson nominated Duval for appointment to the brevet grade of major general of volunteers, to rank from March 13, 1865, and the U.S. Senate confirmed the nomination on May 4, 1866.^[2]

After completing his Union Army service, Duval returned to West Virginia, where he served as member of the West Virginia Senate and as the state's adjutant general from 1867 to 1869. He was elected as a Republican to the Forty-first Congress (March 4, 1869–March 3, 1871). He declined to be a candidate for renomination in 1870.

He then served as States Assessor of Internal Revenue in 1871 and 1872. He worked as the U.S. Collector of Internal Revenue for the first district of West Virginia from 1872 to 1884. He served as member of the West Virginia House of Delegates from 1887 to 1889.

Duval died in Wellsburg, West Virginia, on July 10, 1902, and was buried at Brooke Cemetery. His country home, known as the Gen. I.H. Duval Mansion, was listed on the National Register of Historic Places in 1986.^[3]

• List of American Civil War generals (Union)
• United States congressional delegations from West Virginia

• Eicher, John H., and David J. Eicher, Civil War High Commands. Stanford: Stanford University Press, 2001. ISBN 0-8047-3641-3.

  This article incorporates public domain material from the Biographical Directory of the United States Congress

• United States Congress. "Isaac H. Duval (id: D000576)". Biographical Directory of the United States Congress. Retrieved on 2008-02-12

• Dillon, Richard H., and Shaw, Charles, Texas Argonauts : Isaac H. Duval and the California Gold Rush. San Francisco: Book Club of California, 1987. OCLC 18311782.

• Duval biography