The original castle was built here in 1311 during the reign of Edward II, but by 1570 Lord Kerry had replaced this ancient stronghold with a new structure. This second castle would become a focal point of the bitter struggles between Irish lords and English forces during the late Tudor period.

The castle’s most dramatic years came during the 1580s when it changed hands multiple times amidst fierce fighting. After being besieged in 1580, Thomas Fitzmaurice, Lord of Kerry, twice attacked the English garrison holding his family’s former stronghold in 1582. On the second attempt, the English defenders suffered such heavy casualties that they were forced to abandon Ardfert entirely. The castle’s fate was sealed in 1600 when Sir Charles Wilmot arrived with superior firepower. According to Pacata Hibernia, published in 1633, the defenders held out for nine days, even using fire to destroy the wooden siege works Wilmot’s men had placed against the walls. The turning point came when Wilmot borrowed a saker cannon from an English merchant ship; though the weapon was too small to breach the thick walls, the mere sight of it convinced the garrison to surrender. Wilmot hanged the constable but spared the remaining eight defenders, along with the women and children.

Patrick Fitzmaurice, Lord Kerry, rebuilt the castle in 1637, but his political allegiances during the turbulent 1640s would prove its final undoing. After siding with the Puritans during the Cromwellian war, he fled to England on 13 February 1642, abandoning his rebuilt fortress. The Council of the Confederates in Kerry, determined to prevent the castle from falling into enemy hands again, ordered Captain Patrick Lawlor to burn Ardfert Castle to the ground. He carried out these orders so thoroughly that today, visitors to this site between the cathedral and parish rooms will find no visible trace of the castle that once dominated this strategic position in north Kerry.