Warriors going into the fray  during re-enactments at the Battle of Clontarf Festival in Saint Anne’s Park in Dublin last weekend. The 1,000th anniversary of the actual battle falls today. Photograph: Aidan Crawley/The Irish Times

Today marks the 1,000th anniversary of the Battle of Clontarf. As in the way of all such things, social media boffins hav e taken to Twi(...)