William P. Duvall[a] (January 13, 1847 – March 1, 1920) was a career officer in the United States Army.

During the Spanish–American War, Duvall was promoted to temporary major and lieutenant colonel, and served in staff and command assignments including chief of Ordnance for Second Army Corps.

[2] Robert Duvall was a Union Army veteran of the American Civil War and served as a captain in the Cavalry regiment commanded by William Henry Purnell.

[4] From July 1884 to September 1889, Duvall performed special duty in the office of the Adjutant General of the United States Army, first as disbursing officer for the World Cotton Centennial in New Orleans, the Centenniel Exposition in Cincinnati, and the Southern Exposition in Louisville, then as recorder for the Army board that reviewed and acted on claims for lost and damaged property in Kansas during the American Civil War.

[4] In addition to serving as chief of Ordnance, Duvall was the acting Judge Advocate for the Second Army Corps from October 1898 to May 1899.

[4] From July to October 1906, he performed detached duty as an observer during maneuvers of the Imperial German Army.

[4] Duvall was on a leave of absence in China from December 1910 to January 1911, when he attained the mandatory retirement age of 64.

[4] After his retirement from the military, Duvall traveled the world, including time in Burma, India, the Malay States, Java, China, Italy, Germany and France.

[4] Assigned to command the army's Southeastern Department despite being over 70 years old, Duvall served at its Charleston, South Carolina headquarters until January 1918, when he retired for the second time.

[4] Fort Duvall, a Coast Artillery post that was part of the Harbor Defenses of Boston, was in operation from 1917 to 1974.

[6] Lee later took the name Mary, and was the wife of Louis Eugene Marié, an architect and United States Navy veteran of the Spanish–American War.