 In January 1643, at Rathconnell near Mullingar, Dillon attacked a second relief force as it returned to Dublin with the remnants of Ranelagh's garrison.His regiment assisted Thomas Preston, 1st Viscount Tara in capturing Roscommon and Jamestown.In 1647 his regiment was destroyed, along with much of the Confederate's Leinster army, at the Battle of Dungan's Hill, when they were defeated by an English Parliamentarian army which by that time held Dublin.