[1] Cooper attended the University of Virginia from 1832 until 1834; his classmates included future Civil War generals Carnot Posey, Lafayette McLaws, and John B. Magruder.

He served as a captain under the command of Colonel Jefferson Davis, participating in the battles of Monterrey and Buena Vista.

[1] Prior to the Civil War, General Cooper was also a slave owner, holding eleven enslaved people in 1860 when he resided in the Tishomingo area of the Chickasaw Nation.

After the Treaty of 1866 was signed abolishing slavery in the Chickasaw Nation, the people General Cooper enslaved were granted their freedom.

[1] In May, Secretary of War Leroy Pope Walker sent Cooper a letter authorizing him to "take measures to secure the protection of these tribes in their present country from the agrarian rapacity of the North."

Given brigade command, Cooper pursued the Creek Indian leader Opothleyahola in November and December, when the latter led his loyal Union followers toward Kansas.

Cooper's brigade fought at the battles of Round Mountain[6] and Chusto-Talasah,[7] winning a decisive victory at Chustenahlah.

[1] After the war, Cooper continued to live in the Indian Territory and was an ardent supporter of Choctaw and Chickasaw land claims against the Federal government.