 The castle was developed over time, and by the fifteenth century was a mid-size fortified tower house.The two branches of the original family remained close through the centuries and during the worst of the Penal Laws, the Dunsany branch, having survived transportation to Connacht under Cromwell and other difficulties, converted to the Church of Ireland, and held Killeen in trust for the elder branch, which remained Roman Catholic.Unlike some arrangements of this sort, Killeen was formally returned when the legal situation changed.