Given that Hiram receipted for an issue of clothing on March 31, 1864 and that he does not appear on the October 31, 1864 roll indicates that he must have been dropped from the rolls during the intervening period. His side kick in the band, Jacob Lemley, also receipted for that same issue of clothing and does appear on the two subsequent musters.
As Jacob enlisted March, 1862, it's reasonable to assume that Hiram enlisted at the same time, or sometime within the next two years.
A review of his letters and Jacob's diary should thresh out his service history.
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H. E. Hatfield, Non-commissioned staff, 48th Virginia Infantry, receipted for an issue of clothing March 29, 1864, no other record
M347: Unfiled Papers and Slips Belonging in Confederate Compiled Service Records
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Jacob Lemley, enlisted March 9, 1862 at Winchester, Va. by Col. Campbel for the war, receipted for an issue of clothing March 29, 1864, recorded present on the only two surviving muster rolls for the Field & Staff, that of October 31, 1864, covering the period Apr. 30 to Oct. 31, 1864, and the Nov./Dec., 1864 muster
M324: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Virginia