Alexander Macomb (1782–1841) was a major in the United States Army Corps of Engineers serving as chief engineer of coastal fortifications in Georgia and the Carolinas. With one brief hiatus, 1800–01, the native of Detroit served in the regular army from 1798 until his death, starting as a cornet and ending with thirteen years as major general and army commander in chief. Macomb toured the southeastern frontier as secretary to General James Wilkinson, 1801–02, was one of the first two students selected for instruction at the new United States Military Academy at West Point in the latter year, and served with distinction in the War of 1812. He wrote A Treatise on Martial Law, and Courts-Martial; as practised in the United States of America (Charleston, S.C., 1809; Sowerby, description begins E. Millicent Sowerby, comp., Catalogue of the Library of Thomas Jefferson, 1952–59, 5 vols. description ends no. 2021), the first such American study (ANB description begins John A. Garraty and Mark C. Carnes, eds., American National Biography, 1999, 24 vols. description ends ; DAB description begins Allen Johnson and Dumas Malone, eds., Dictionary of American Biography, 1928–36, 20 vols. description ends ; Heitman, U.S. Army description begins Francis B. Heitman, comp., Historical Register and Dictionary of the United States Army, 1903, 2 vols. description ends , 1:680; Allan Seymour Everest, The Military Career of Alexander Macomb and Macomb at Plattsburgh, 1814 [1989]).

On 6 Oct. 1809 John Smith chief clerk of the War Department, wrote TJ from Washington that the day before he had received TJ’s note enclosing this letter and had immediately forwarded the latter to Macomb at Charleston, South Carolina, “where he is at present engaged in the duties of his profession” (RC in MHi; at foot of text: “Thomas Jefferson Esqr”; endorsed by TJ as received 11 Oct. 1809 and so recorded in SJL). TJ’s covering note to Smith is not recorded in SJL and has not been found.