Brian Boru is the most famous Irish person before the modern era, whose death at the Battle of Clontarf in 1014 is one of the few events in the whole of Ireland's medieval history to retain a place in the popular imagination. This book proposes a far-reaching reassessment of Brian Boru and Clontarf. It offers a new interpretation of the role of the Vikings in Irish affairs and explains how Brian emerged from obscurity to attain the high-kingship of Ireland because of his exploitation of the Viking presence. It concludes that Clontarf was deemed a triumph, despite Brian's death, because of what he averted - a major new Viking offensive in Ireland - on that fateful day. "The book's straightforward and accessible style appeal to students and general readers."--Irish Literary Supplement