O.P. Pettyjohn enlisted July 24, 1863 in Hall County. He was in Co. C, 24th Battalion, Georgia Cavalry until, through consolidation of units, he was transferred to Co. D, 7th Regiment, Georgia Cavalry.
Pvt. Pettyjohn is listed as having been present on all roll calls through October '64. The September/ October roll indicated that he was without a horse.
Pvt. O.P. Pettyjohn surrendered and was paroled on May 8, 1865 in Athens.