COOPER, Samuel, soldier, born in Hackensack, New Jersey, 12 June, 1798; died in Cameron, Virginia, 3 December, 1876. His father, of the same name, served during the Revolutionary war, and fought in the battles of Lexington, Bunker Hill, Monmouth, and Germantown. At the close of the war, having attained the rank of major, he settled in Dutchess county, where he married Miss Mary Horton. He was graduated at the United States military academy in 1815, and promoted to second lieutenant in the artillery. His services were retained on the reorganization of the army after the war of 1812, and he served on garrison duty and in Washington for several years, meanwhile he had been promoted to first lieutenant. From 1828 till 1836 he was aide-de-camp to General Alexander Macomb, becoming captain in June, 1836, and until 1841 was on staff duty at army head-quarters as assistant adjutant general. During the Florida war he was chief of staff to Col. William J. Worth. He remained on special duty in the war department in Washington from 1842 till 1852, was brevetted colonel for meritorious conduct in the prosecution of his duties in connection with the Mexican war, and then, until 1861, was adjutant-general of the United States army, with the rank of colonel of the staff, dating from 1852. For a short time during this period he was secretary of war ad interim. In March, 1861, he resigned his commission and offered his services to the seceding states. He was appointed adjutant and inspector-general of the Confederate army, of which he was the ranking officer, standing first on the list of generals. In 1827 he married a granddaughter of George Mason, of Gunston Hall, Clermont, Fairfax County, Virginia, and subsequent to the civil war, lived in retirement at his country seat near Alexandria, Virginia He was the author of "A Concise System of Instructions and Regulations for the Militia and Volunteers of the United States" (Philadelphia, 1836).