Complex sentence: James attended Mass services there with his Jacobite supporters for a time, however, the victory of the Protestant Williamites in this war meant that the cathedral was restored to Anglican ownership in 1690 when James abandoned Dublin after his defeat at the Battle of the Boyne.
Split into simpler sentences: James attended Mass services there with his Jacobite supporters for a time. However, the victory of the Protestant Williamites in this war meant that the cathedral was restored to Anglican ownership in 1690 when James abandoned Dublin after his defeat at the Battle of the Boyne.