Clear Spring native Kershner was commissioned an assistant surgeon in the U.S. Navy in September 1861, and his first post was aboard USS Cumberland in Chesapeake Bay. On March 8, 1862, during the Battle of the Ironclads, CSS Virginia, also known as Merrimack, rammed Cumberland, which sank without surrendering and took a third of her crew down with her. During the fight, Kershner feverishly tended wounded sailors and Marines, and as the ship went under he was one of the last men to dive from it before being pulled unconscious from the water, apparently after striking his head going overboard. During the rest of the war, he served as a medical officer aboard the ironclads USS New Ironsides, USS Passaic, and USS Choctaw. He made a career in the Navy, was promoted to Surgeon in 1872 and Fleet Surgeon in 1895, retired in 1902, maintained a home at this site from around 1900 until his death in 1916, and his home was demolished in 1947.