At the end of 1593, Maguire was wounded in an attempt to prevent Sir Henry Bagenal and Tyrone from crossing the Erne. In June of the following year he besieged Enniskillen with Hugh Roe O'Donnell, Lord of Tyrconnell. Sir Henry Duke sought to relieve the garrison, but Maguire intercepted him at the Arney River and defeated him in the Battle of the Ford of the Biscuits ("Beal atha na mBriosgaidh"). In the following year he devastated Cavan and was again proclaimed a traitor by the English.