- May 14 Battle of Lewes, 2nd Barons' War: Simon de Montfort the younger, Earl of Leicester, defeats English King Henry III
- Jun 18 The Parliament of Ireland meets at Castledermot in County Kildare, the first definitively known meeting of this Irish legislature
- Aug 5 Anti-Jewish riots break out in Arnstadt Germany
Event of Interest
Aug 21 Kublai Khan accepts the surrender of his younger brother Ariq Böke at Xanadu, at the end of the Mongol civil war