Ed,
I have no information re his death date. There was, however, another Mississippi soldier by the same name.
Charles R. Hemphill, Private, Company I (Choctaw Guards), 15th Regiment Mississippi Volunteers, enlisted September 1, 1862 at Jackson/Brookhaven, Miss. by Capt. Prewitt, last recorded present on the July/August, 1864 muster roll, no further records