He was promoted multiple times for gallant and meritorious service in battle, rising during the course of the war from the rank of second lieutenant to brevet major.

McCrea was born in Mississippi, from where he was appointed to the United States Military Academy at West Point in 1858 as a member of the Class of 1862.

[1] Upon graduation in June 1862, the American Civil War was already in progress: McCrea was commissioned as a second lieutenant with Battery I, 1st U.S.

[1][2] The severity of his wounds compelled him to take a leave of absence which lasted throughout most of 1864; upon his return to active duty, McCrea was an instructor at West Point.

[1][2] After more than forty years of military service, he retired on February 22, 1903–one day after he was promoted to the rank of brigadier general.

[4] McCrea's wife died in 1917, after which he moved in to his daughter and son-in-law's home at West Point, New York.