In 1861, at the age of 19, Scofield joined as a private in Battery D of the 1st Ohio Light Artillery under the command of Colonel James Barnett. His unit took part in battles including Perryville, Chickamauga. When his enlistment ended, he was commissioned as a 2nd lieutenant of the 103rd Ohio Volunteer Infantry, eventually attaining the rank of captain in 1864. During his service, he served largely as an engineer on the staff of Jacob Dolson Cox. Scofield published a book in 1909 detailing his experiences during The Battle of Franklin.