Philemon enlisted in the 10th Missouri in August 1861 after Lincoln requested a certain percentage of men from each state to volunteer. The state of Missouri, a slave state, had a difficult time raising enough regiments. Nine out of the ten companies in the 10th Missouri had men from Illinois and Iowa. After three years of service, the regiment did not veteranize, they disbanded. Philemon returned home to Schuyler County, Illinois in August of 1864. Philemon's brother William had apparently received a draft notice. Philemon decided to volunteer to take William's place - He reenlisted as a veteran in the 12th Illinois Volunteer Regiment.