Hardie, James Allen was born on May 5, 1823 in New York City. Son of Allen Wardwell and Caroline (Cox) Hardie.
Graduated from the United States Military Academy, 1843.
Assistant professor geography, history and ethics United States Military Academy, 1844-1846. Served as major New York Volunteers, 1846-1848. Became Roman Catholic.
Helped raise money to build 1st cathedral church in San Francisco during Mexican War. Commissioned First lieutenant 3d Artillery, United States Army, 1848. Adjutant general Department of Oregon.
Lieutenant colonel on staff General McClellan during Peninsular and Maryland. campaigns, 1861, on staff General Ambrose Burnside in battles around Fredericksburg (in controversy between Burnside and William Franklin over responsibility for disaster on the Rappahannock, 1862, both contestants agreed to use his accurate field dispatches as true record of events). Assistant adjutant general Army of Potomac. Commd brigadier general Volunteers, 1862.
Carried secret personal message making George Meade commander in place of Joseph Hooker just before Gettysburg, 1863. Assistant secretary to the United States Secretary of Army Edwin M. Stanton. Judge advocate general Army of Potomac, 1863.
Promoted major United States Army, 1863, major, 1865. Major chief of Inspector General’ General’ s Office, 1865.