Thomas Williams (1815-1862) was a career artillery officer ot the US Army.

Thomas Williams (1815-1862) was a career artillery officer of the regular US Army whose active, distinguished service was almost entirely on the frontiers of the Old Northwest, Florida, and the Far West until the last year of his life, during which he assumed general responsibilities as a brigadier commanding volunteer troops of combined arms. He died of a gunshot wound at age forty-seven in 1862 while leading his brigade in the Union Army's successful defense of Baton Rouge, Louisiana against a Confederate counterattack.

Williams was literally a child of the War of 1812, having been born in Albany, New York to which his family had temporarily revived in the wake of the British capture of Detroit, where his father had served as a senior officer of American militia troops. Thereafter Thomas Williams fought in every major American conflict preceding the Civil War, including Illinois' Black Hawk War (1832), in which he accompanied his father's Michigan troops as a teenaged private; the Second Seminole War (1835-1842); the Mexican War (1846-1848); and the Utah War (1857-1858). During the late 1850s, when Thomas Williams wrote most of the letters in this collection, he was a captain in the Fourth U.S. Artillery, the regiment in which he had served since graduating from the U.S. Military Academy two decades earlier, standing twelfth in the Class of 1837. In addition, he held the rank of major by brevet, reflecting his receipt of two brevet promotions for gallant and meritorious conduct during the Mexican War battles of Contereras, Churubsco, and Capultepec. During a portion of that conflict, Williams served as an aide to General Winfield Scott as well as a battery commander. In May 1861, with the outbreak of the Civil War, Williams was promoted to the substantive grade of major and transferred to the Fifth U.S. Artillery, a new regular regiment in which his son, Thomas Williams, Jr., simultaneously received a direct commission as a first lieutenant. Notwithstanding the senior Williams' appointment, four months later as a brigadier general for volunteers and his departure from the Fifth for greater command responsibilities, that regiment and his continuing rank as its major defined Williams' regular army status at the time of death. Note: Biographical sketch written by Bill MacKinnon of Santa Barbara. Sketch was received by David Whittaker 5 March 2009. Full sketch by MacKinnon is available in collection.