The well-known folk song "Johnny, I Hardly Knew Ye" is widely regarded as a traditional Irish anti-war song which was later rewritten as the pro-war "When Johnny Comes Marching Home." Jonathan Lighter, Lecturer in English at the University of Tennessee and editor of the Historical Dictionary of American Slang, reveals the surprising history of "Johnny," uncovering its roots and tracing its ever-changing role in popular culture up to the present day.