Nelson H. Davis was a career soldier in the United States Army. Graduating from the United States Military Academy at West Point in 1845, he served in the Mexican-American War, the American Civil War and in actions against the Apache people in New Mexico. His service in the Civil War began as a colonel commanding the 7th Massachusetts. However, after a few months, he was transferred as a major to a staff position within the Army of the Potomac. In this capacity, he caught the attention of Maj. Gen. George B. McClellan, who eventually assigned Davis to duty with his headquarters staff. On July 10, 1868, President Andrew Johnson nominated Davis for the award of the honorary grade of brevet brigadier general, U.S.A., Regular Army, to rank from March 13, 1865, for meritorious and efficient services during the war, and the U.S. Senate confirmed the award on July 28, 1868. Nelson H. Davis retired from the army as a brigadier general in 1885. He died at Governor's Island, New York, on May 15, 1890.