The History of the Castle By Robert Mc Guire
For over 250 years the Fitzgeralds, the earls of Desmond (south Munster) were the most powerful family in Medieval Munster. Also known as the Geraldines, they ruled their lordship like kings. Castleisland Castle was one of their chief strongholds. This castle was referred to during medieval times as the “Castle of the Island” or simply “the Island”.It was constructed by the
Anglo-Norman, Geoffrey De Marisco on the banks of the river Maine in the year 1226.

The nal earl of Desmond, Gerald Fitzgerald failed in his rebellion against the Elizabethan Crown forces. He was ruthlessly beheaded deep in the dense woods of Glanageenty near Castleisland in November 1583.

The reign of the Desmond Fitzgeralds in Castleisland had finally come to an end. Sir William Herbert of Wales was granted the dispossessed lands. Herbert and other loyal tenants of his Protestant elite resided in Castleisland Castle from 1590, until it was finally abandoned for a more suitable mansion in 1661.