When Ó Néill approved of conditions for himself and on behalf of his vassals, preparations began. Roger Mortimer, 3rd Baron Mortimer, received news from Irish sources around this time that an invasion was about to take place, and made his way to Ireland, where he held land mainly in and around the castle and town of Trim. He had previously fought against the Bruces at Bannockburn where he was taken prisoner and freed to return King Edward II's royal seal, lost in the rout.