Merrion Castle

After the Fitzwiliams moved to Mount Merrion House in about 1710 the castle fell into ruin, and it was demolished in 1780, though there were remains visible as late as 1837.

Until the late sixteenth-century Baggotrath was the Fitzwilliams' most favoured residence, for possession of which they fought a bitter private war with the Cornwalsh family in the 1440s, and were even prepared to resort to murder to assert their rights.

It was Sir Thomas Fitzwilliam, grandfather of the first Viscount, who in the reign of Elizabeth I made Merrion Castle the principal family residence.

The Fitzwilliams, who were staunch Royalists, installed a strong garrison; but in June 1642 the castle was betrayed to the Parliamentary side,[2] and remained in Parliament's hands until the Restoration.

Given the traditional loyalty of his family to the Stuart dynasty, he might well have expected its speedy recovery in 1660; but the bitter divisions in post-Restoration Ireland, which saw Tyrconnell accused by his enemies of having been a supporter of Oliver Cromwell, caused a delay in the full restitution of his lands, and he did not recover Merrion until 1663.