The history of Ireland in the later Middle Ages becomes immensely complicated due to the fractious character of Irish families and their habit of forming, and then breaking, alliances with each other. The south-west of the country (now Counties Kerry and Cork) was for a long time dominated by the MacCarthy Mórs, Kings of Desmond under which were three cadet branches ruling over their own territories whenever not feuding among themselves. Following the death of the last of King of Desmond, Donal IX in 1596 leaving only an illegitimate son, a dispute broke out between various members of these septs over who was entitled to claim his position. One of those who sought to become the new MacCarthy Mór was Dermot MacOwen MacCarthy, a descendant of Dermod, the third son of Cormac Fionn MacCarthy Mór (1170-1242), King of Desmond (although for the purposes of his claim MacOwen MacCarthy contended he was descended from Cormac’s eldest son). But at the same time Dermot MacOwen was in dispute with a cousin, Donogh MacCormac MacCarthy for the title of Lord of Duhallow, one of the three subordinate septs of Desmond. Yet in 1598 the two men joined forces to attack Castle Hyde, home of the settler Arthur Hyde, which after a three-day siege was captured and burnt. They then reverted to their earlier quarrel over the Lordship of Duhallow. Under these circumstances, it is no wonder the Irish were so often unable to defeat their common foe, the invading English.

Following the death of Donogh MacCormac MacCarthy during a skirmish in the Clare-Galway region in 1601, Dermot MacOwen MacCarthy became the undisputed Lord o Duhallow and it is likely that around this time (or following his release by the English government in the aftermath of the Battle of Kinsale during which he had been imprisoned) work began on the construction of a his new residence immediately south of Kanturk, County Cork: on a map of Ireland made by John Norden between 1609 and 1611, there is a castle shown at “Cantork” (Kanturk). It is sometimes proposed that Donogh MacCormac was responsible for initiating work on this castle, but given that he died in 1601 that seems unlikely. Seemingly in order to pay for the building’s construction, MacCormac MacCarthy mortgaged large tracts of his territory even though under Gaelic law all such land was deemed communal property. The mortgagee was Sir Philip Percival who had arrived in Ireland in 1579 and by such means was able to amass a large estate for himself. No documentation survives about Kanturk Castle’s construction, but one legend claims it was built by seven stone-masons all called named John: for a time the building was known as ‘Carrig-na-Shane-Saor’ (the Rock of John the Mason). Work on the site seems to have stopped in 1618 after English settlers in the area objected to the castle being too large and too fortified. Accordingly the English Privy Council ordered work be discontinued. It is said that MacCormac MacCarthy was so angry at this instruction that he ordered the blue ceramic tiles on the castle’s roof be smashed and thrown into a nearby stream, which thereafter has been known as Bluepool.

Kanturk Castle, otherwise called Old Court, rises beside the Dalua river, a tributary of the Blackwater. It is constructed of local limestone rubble, with cut stone used for the mullioned and transomed windows as well as the hoods, cornices, quoins and corbels. The same cut limestone can also be seen around entrance doors, and what remain of the chimney pieces on each floor inside the building. The castle is rectangular in form, measuring twenty-eight by eleven metres and rising four storeys with a five storey, twenty-nine metre high tower at each corner. The main entrance is on the western side, a work of Italian Renaissance inspiration with an elaborate entablature above the Ionic columns on either side of the round headed door frame. Since it is located on what would have been the first floor, presumably the original approach was via a flight of steps (on the other hand, given the gun holes on other parts of the building, perhaps the raised entrance served as a defensive device?) To the rear of the castle is another more familiar arched entrance on the ground floor. Inside the floors are all gone. One of the stories about Kanturk Castle is that, after his fit of pique over the Privy Council order, MacCormac MacCarthy never occupied the place. However, given the quality of the remaining chimney pieces (some were later removed to Lohort Castle), this seems unlikely. Whether the building was ever fully completed or thereafter much used remains open to conjecture.

Dermot MacCormac MacCarthy was succeeded by his son, Dermot Oge, who married Julia, daughter of Donal, last O’Sullivan Beare and widow of Sir Nicholas Browne whose father had bought the vast MacCarthy estates in Kerry. Having participated in the Confederate Wars of the 1640s, both Dermot Oge and his son were killed in 1652 at Knocknaclashy, west of Mallow, in the course of battle against a Cromwellian force led by Lord Broghill. Twenty years earlier financial exigency had led him to enter into the aforementioned mortgage agreement with Sir Philip Percival, so the family’s ongoing possession of their land was already vulnerable. In the aftermath of the restoration of the English monarchy in 1660 the Court of Claims denied the MacCarthys Equity of Redemption on the old mortgage.  Instead ownership of the Lordship of Duhallow and the manor of Kanturk was awarded to ‘Sir Philip Percival, baronet, minor, grandson and heir of the said Sir Philip the Elder.’ Ultimately Sir Philip’s great-grandson Sir John Perceval became Baron of Burton, county Cork, in 1715, Viscount Perceval, of Kanturk, in 1722 and finally Earl of Egmont in 1733. Although Kanturk Castle appears in the background of a portrait of the second earl and his wife painted c.1759 by Sir Joshua Reynolds (now in Bradford Museum), the family made their residence at Lohort Castle, another former MacCarthy stronghold. In 1900 the seventh earl’s widow presented Kanturk Castle to England’s National Trust, which had only been founded five years earlier, on condition the building be maintained in the condition in which it was received. For much of the last century the castle was the National Trust’s only property in the Republic. In September 1951, it granted the building to An Taisce (a long-established charitable organisation engaged in the preservation and protection of  Ireland’s natural and built heritage) on a 1,000 year lease and at a rent of one shilling per annum if so demanded. In 2000 the National Trust officially transferred the title deeds of Kanturk Castle to An Taisce, which is now responsible for the building, a national monument, on behalf of the Irish people.