Duvall was one of several retired officers recalled to active duty for World War I; despite being over 70 years old, he commanded the army's Southeastern Department from August 1917 to January 1918, when he retired again. He died in Coronado, California on March 1, 1920, and was buried at West Point Cemetery.
After receiving his commission, Duvall was assigned to the 5th Artillery Regiment, and he served at coastal artillery posts including Fort Adams, Rhode Island from 1869 to 1872 and Fort Monroe, Virginia in the summer of 1872.[4] From 1872 to 1875, he served on the faculty at West Point as an assistant professor of mathematics.[4] In addition, he served as an instructor of Artillery tactics, then as an instructor of Infantry tactics.[4] From 1875 to 1877, Duvall acted as West Point's acting commissary of subsistence.[4] He was promoted to first lieutenant in April 1877.[4]
From September 1889 to March 1898, Duvall served in artillery assignments at Fort Schuyler, New York and Fort Monroe, Virginia.[4] He was promoted to captain in the 1st Artillery in March 1898.[4]
In July 1899, Duvall was assigned to command the 26th U. S. Volunteer Infantry, and in September 1899 he was promoted to temporary colonel as commander of the 48th U. S. Volunteer Infantry.[4] Duvall commanded his regiment in the Philippines during the Philippine–American War, including service at La Loma, La Union, and Benguet.[4] He returned to the United States in June 1901 and reverted to his permanent rank of captain.[4]
Duvall served in coastal artillery assignments at Fort Wadsworth, New York, Fort Howard, Maryland, Fort Columbus, New York, and Fort Williams, Maine from July 1901 to September 1903, and he was promoted to permanent major in September 1901.[4] From August 1903 to December 1905, Duvall served on the War Department General Staff.[4] From December 1905 to March 1906, he served as principal assistant to the Chief of Artillery.[4] He was promoted to lieutenant colonel in February 1906, and brigadier general in March 1906.[4]
Later career
After his promotion to brigadier general, Duvall commanded the Department of the Gulf from April 1906 to February 1907.[4] From July to October 1906, he performed detached duty as an observer during maneuvers of the Imperial German Army.[4] From February 1907 to February 1909, Duvall was assigned as assistant to the Army Chief of Staff.[4] In October 1907, he was promoted to major general.[4] From April 1909 to December 1910, he commanded the Philippine Division.[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]
In retirement, he took up residence in the Sand Hills neighborhood of Augusta, Georgia.[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]
In August 1917, Duvall was one of several retired officers who were recalled to active duty for World War I.[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]