DUNCAN, Thomas, soldier, born in Kaskaskia, Ill, 14 April 1819 ; died in Washington, D. C., 7 January 1887. He early became a soldier, and served as a private in the Illinois mounted volunteers in 1832, during the Black Hawk war. Subsequently he was connected for some years with military expeditions, and in 1846 was appointed from Illinois as 1st lieutenant in the U. S. mounted rifles, now the 3d cavalry, He served during the war with Mexico, and was engaged in the siege and surrender of Vera Cruz. Later he was on recruiting duty, was promoted captain in March 1848, and was on garrison duty at various posts till 1856. He was stationed with his regiment in New Mexico till 1862, had command of Fort Burgwin, Fort Massachusetts, Fort Garland, and Fort Union, participated in the Navajo expedition of 1858, defeated the Comanche Indians in the action at Hatch's Ranch in May 1861, and became major of his regiment in June 1861. During the civil war he had command of Fort Craig in New Mexico, was in charge of the cavalry forces at the battle of Valverde, N. M., and of his regiment in the action in Albuquerque, N. M., where a cannonball carried a portion of his skull away. He was assistant provost marshal of Iowa in 1863'6, became lieutenant colonel of the 5th U. S. cavalry in July 1866, and commanded the district of Nashville till September 1868. He then was ordered to the Department of the Platte, was stationed successively at Fort McPherson and Fort D. A. Russell, and was afterward in charge of the construction of Sidney barracks, till November 1871. Failing health compelled him to obtain sick leave till January 1873, when he was retired from active service. Colonel Duncan received several brevets, including that of brigadier general, for his services during the civil war.