The site has a long and complex history, beginning as the ancient court and manor of Dermochi, or Darragh-Mochua, first documented in 1185 when it was associated with the monks of Limerick and Magio Abbey. By 1317, Isabella de Cogan and Garrett Roche, Lord of Fernagen, were claiming rents on the property, whilst in 1300 the town of Dermochii was assessed two marks to contribute to the Scotch wars, indicating its economic importance at the time.

The castle’s decline can be traced through various historical documents. In 1583, it was already described as ‘broken’ when held by Pierce Grace. By 1607, Ballynecourty Castle, along with Darragh and surrounding lands, was granted to Edward Fitz Harys, though there were competing claims from Downe Irish, who argued it belonged to a chapel of ease of the College of Kilmallock. The 1654-56 Civil Survey of Limerick noted that Sir Edward Fitz Harris, described as ‘an Irish Papist’, owned ‘Ballynecourta halfe a plowland with a But of an Old Castle and an Orchard thereupon’; the terrier of the Down Survey parish map suggested the castle could still be made habitable with minor repairs.

By the 19th century, the castle had completely vanished from the landscape. When the Ordnance Survey team arrived in 1840, they found only ‘a heap of rubbish’ where the tower house once stood, making it impossible to record its dimensions. The site was marked on their maps simply as ‘Site of Castle’, and today no surface remains are visible of this once-important medieval stronghold that featured prominently on the 1654-56 Down Survey map of Coshlea Barony.