Newtown Butler, battle of, 1689. In the summer of 1689 Enniskillen, second only to Derry in importance in Northern Ireland, still held out against the Jacobite advance. But when Mountcashel was ordered to pinch out the town, its defenders got their blow in first, attacking his troops at Newtown Butler on 31 July. Though heavily outnumbered, the Williamite forces carried the day.