On February 1, 1862, Leonard enlisted on the side of the Union in the American Civil War in Company F., 88 N.Y. Volunteers, an Irish regiment. After seven days of battles, he was captured by the Confederate Army. While held in a facility in Annapolis, Maryland that housed prisoners of war captured by both sides, he contracted scorbutic dysentery and died on September 26, 1862.Winter 1999, p. 140 (quoting Hazeltine in the Macon Telegraph, 1867).
