Forgiven by the press and apparently by the Army, he rejoined the active military as a major in command of a cavalry regiment. He commanded the Cavalry Reserve Brigade briefly, but was denied the promotion and command when another officer his junior took command. He is noted for his July 1863 actions at the Battle of Fairfield where his small cavalry regiment took on two crack Confederate Cavalry Regiments reinforced with light artillery. He was severely wounded in the melee and his right arm had to be amputated while he was a prisoner of war. "Old Paddy" was exchanged on parole in September of that year.
