This volume contains the proceedings of a conference held in Trinity College Dublin in April 2014 marking the millennium of the Battle of Clontarf, one of the landmark events in Irish history. Organized by the editor in partnership with Dublin City Council, the conference heard from leading experts in the fields of Irish history, Scandinavian history, Celtic studies and archaeology, speakers being drawn from universities throughout Ireland, Great Britain and further afield, as well as specialists from the National Museum and elsewhere. The essays seek to establish the truth of what really happened at the Battle of Clontarf for a 21st-century audience and re-evaluate the role of Brian Boru in the light of the latest research - topics that are discussed in papers by Edel Bhreathnach, Maire Ni Mhaonaigh, Sean Duffy, Denis Casey, Clare Downham, Eoin O'Flynn and Andrew Halpin. Other contributors such as Donnchadh O Corrain, Colman Etchingham, Catherine Swift and Bart Jaski discuss their recent investigations into the rise of Brian's dynasty of Dal Cais, the subject of the high-kingship of Ireland and the role of the Vikings in medieval Ireland. The legacy of Brian and of Clontarf is explore by Marie Therese Flanagan, Paul McCotter, Meidhbhin Ni Urdail and Alex Woolf.