The earliest recorded mention places it under Robert Purcell’s control during the tenure of T. f. Gerald, whilst by 1317, the castle and its surrounding hamlets of Ballymonyn were held by Gilbert de Burgo. The name itself, as noted by the scholar Dr. Joyce in his work “Irish Names,” derives from the Irish meaning “fort of the soft land,” perhaps referring to the marshy or yielding nature of the ground upon which it stood.

The castle changed hands numerous times throughout the centuries, reflecting the turbulent nature of Irish land ownership. Around 1550, Edmund Hubert took possession of Cahermoyle, and in 1583, his son Morris passed it to his younger son Gerrot. The Harbert family, specifically a Garret Harbert, maintained control of the castle in both 1609 and 1637, as documented in various chancery inquisitions of the period. These transfers of ownership were meticulously recorded in various administrative documents, including the Calendar of State Papers Ireland and Revenue Exchequer Orders.

By the mid-17th century, the castle appears in records under various spellings; Cahir mo Eaghill, Cahermeghill, and Cahirmeaghill; all referring to the same location in Rathronan. In 1655, it was associated with James mac Shane, and later became part of Sir Daniel O’Brien’s estate, which was subsequently confirmed to both him and Sir Thomas Southwell. These historical details, originally compiled by the antiquarian Westropp in 1906-7 and more recently organised by Caimin O’Brien in 2020, provide a fascinating glimpse into the changing fortunes of this Limerick fortress across nearly four centuries of Irish history.