Corcomroe, Ennistymon, Kilmanaheen, Maghera..
The founding of the original Ennistymon Castle is somewhat unclear. One source suggests it may have been built c.1560 by Domhnall (Donald) O’Brien. However, there is evidence to suggest that he may have superseded Donough MacDonall O’Conor of Corcomroe who also built nearby Dough Castle in Lahinch. Much of the surrounding area had long been in the possession of the O’Connors. For example, in 1574 the castle of Inysdyman was described as being held by an O’Connor under "Sir Domhnall O’Brien, Knight".
In 1582, according to one source, all O’Connor properties in the area were officially transferred to Turlough O’Brien, with the possible exception of Ennistymon which may have remained - nominally at least - an O’Connor castle for some time after that. Domhnall is, however, credited with founding a branch of the O’Brien family at Ennistymon Castle. Sir Domhnall was made Governor of Clare in 1576, and died in 1579. His son, Sir Turlough O’Brien, became High Sheriff of Clare while another son, also Domhnall, was later Protestant Bishop elect of Killaloe. At one point, Sir Turlough owned over 2,000 acres in the area, including the castle at Ennistymon. And in 1588, at the height of the Spanish Armada, he was given permission to arrest and torture any Spaniards found in the country. Conversely, Sir Turlough’s son Tadhg joined the rebel forces of Red Hugh O’Donnell, and was mortally wounded after a large-scale skirmish into the area which included one foray that brought them "to the gate of Inis-Dimain". By 1619, the Earl of Thomond was recorded as holding "the castle, town and three quarters (c. 360 acres) called Innisdyman". During the Confederate War, in 1645, Sir Daniel O’Brien of Ennistymon Castle was appointed to organise an exchange of prisoners with the commanders of English troops in Connacht. After that war, the Earl of Thomond decided to let most of the castles in the region to English Protestants, and so Neptune Blood became the leaseholder of Ennistymon Castle in 1656. Three years later it was let to an Edward Fitzgerald. At the end of the O’Regan lease, Francis took the decision to sell the hotel, thus ending a connection which stretched back -almost unbroken- to the original O’Brien’s of Ennistymon Castle some four hundred years previous.