The Clonbrock estate was established in the 1580s when 3,000 acres of land and turbary was purchased by Thomas Dillon from Teige O’Kelly. A castle was subsequently built there. The Dillons of Clonbrock also retained landholdings in several counties outside Galway, including Meath, Roscommon and Westmeath. Some of these lands, then in the possession of Richard Dillon of Clonbrock (1603-76) were sequestered by the Crown after the rebellion of 1641 but were subsequently restored to his possession in 1663 following the restoration of King Charles II. Subsequent threats to the integrity of the Galway estate were avoided by the family’s conversion to Protestantism in the early eighteenth century.