 Ownership then passed to the Earl's brother Donal O'Brien, who was responsible for inserting many of the castle's windows as well as the fireplace on the fifth floor, which bears the date 1603.Donal's grandson was the celebrated third Viscount Clare who resided at Carrigaholt and raised a regiment of horses known as the "Yellow Dragoons" for the House of Stuart King James II of England's armies.After the forfeiture of his extensive 230 km2 (57,000-acre) estate by the Williamites, the castle was acquired by the Burton family.