During the American Civil War, Carson led a regiment of mostly-Hispanic volunteers from New Mexico on the side of the Union at the Battle of Valverde in 1862. When the Confederate threat was eliminated in New Mexico, Carson led forces to suppress the Navajo, Mescalero Apache, Kiowa, and Comanche tribes by destroying their food sources. He was brevetted a Brigadier General and took command of Fort Garland, Colorado. He was there only briefly, as poor health forced him to retire from military life.