Davis graduated from the United States Military Academy at West Point in 1846 and served as an infantry officer in the Mexican-American War.

He became colonel of the 7th Massachusetts Infantry Regiment but 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 in the Regular Army, to rank from March 13, 1865, for meritorious and efficient services during the war.

[2][3] After the war Davis continued his military service and eventually became Inspector General of the U.S. Army in 1885.