James S. Gillett, lawyer, military officer, and adjutant general, son of Jonathan and Hannah (Shackleford) Gillett, was born at Lincoln, Kentucky, in 1810. Before 1820 his family moved to Howard County, Missouri, with the family of Henry Smith, his brother-in-law, who was later appointed by Antonio López de Santa Anna to be the first provisional governor of Texas. Three of his sisters were married at different times to Smith. In 1827 Jonathan, with his son Roswell and daughters Catherine and Sarah, left Missouri with Smith and his family to go to Texas. In March 1827 Jonathan applied for a land grant from Mexico and returned to Missouri for his family. Before he could return to Texas, he and his wife died. James remained in Missouri with a sister and her husband, but shortly thereafter left for Santa Fe. On the trip his party was attacked by Osage Indians, and he and three other youths were captured. The Indians released them unharmed after two weeks. They made their way to Santa Fe, where Gillett lived for several years and mastered Spanish.
He next moved to Van Buren, Arkansas, where he studied law and was admitted to the bar. In 1839 he moved to Paris, Texas. In 1846, when Texas was admitted to the Union, he was elected the first representative from Lamar County to the First Legislature, which met on February 16, 1846. When Mexico threatened war over the annexation of Texas, Gillett organized a company as captain in Col. John C. Hays's Second Regiment, Texas Rangers. War was declared on May 9, 1846. Gillett's company was stationed along the frontier with the companies of captains Johnston, Ross, Highsmith, and Baylor under Lt. Col. Peter H. Bell. Gillett was promoted to major on July 11, 1848, and served until February 15, 1849. In 1850 he married Elizabeth Harper, daughter of Capt. R. H. Harper, a planter from North Carolina, who had in 1846 established a plantation in Washington County. They had five children. The first two boys died in infancy. Another, James Buchanan Gillett, born in 1856, was a Texas Ranger, author, and rancher.
In 1851 Gillett ran for lieutenant governor but was defeated. He was appointed adjutant general of Texas on November 24, 1851, by Governor Bell. On October 10, 1855, fire destroyed the adjutant general's office and all records, including all muster rolls and evidence upon which county and land warrants were issued. The following year the legislature did not fund the office, and Governor Elisha M. Pease suspended it on February 4, 1856. In 1858 Gillett was appointed quartermaster of the Texas Rangers.
In the early days of the Confederacy he was rejected for military service because of age. When there was a call for more men, he enlisted in Capt. W. H. D. Carrington's company, on July 15, 1863, and was mustered out March 16, 1864. He returned from war broken in health and spirit, with his slaves freed and his landholdings in Austin and Grimes County not very productive. Though there was little law practice under Reconstruction, he managed to support his family. Because of his wife's ill health, they moved to Lampasas in 1872. Gillett died there in April 1874. There is a Texas historical marker at his gravesite.