In 1861, Cyrus B. Lower became one of his nation's early responders to President Abraham Lincoln's call for volunteers to defend Washington, D.C. following the April 1861 fall of Fort Sumter to the Confederate States Army. During the early summer, he left his home state and headed for Poland, Ohio where, on June 21, he enrolled for Civil War military service, and mustered in as a private with Company E of the 23rd Ohio Infantry. After fighting with his regiment in the Battle of Carnifex Ferry, Virginia on September 10, he was then wounded in action in Maryland on September 18 while fighting with his regiment near Antietam. Shot in the left hand by a rifle, he sustained further damage when the ball traveled up and through his wrist joint. After three months of treatment for his injuries and subsequent convalescence at a Union Army hospital in New York, he returned to service with the 23rd Ohio at its headquarters at Camp White in West Virginia, but was quickly discharged on a surgeon's certificate and sent home to Pennsylvania when his superiors determined that he was still not fully recuperated.Hruska, Judy. "Cyrus B. Lower". New Castle, Pennsylvania: New Castle News, November 13, 2000, p. 1.
