The castle’s story begins in 1618 when Richard Devereux, the third Earl of Essex, granted the lands comprising nineteen tates across seventeen townlands to John Hadsor of Cappoge, County Louth. The Hadsor family, originally Anglo-Normans called de Hedesor from Worcestershire, had been established in Ireland since the late twelfth century. John’s half-brother Richard, who likely secured the grant for him, was both lord of Cappoge and an advisor to the English government on Irish affairs; a propagandist for English settlement who nonetheless helped his family acquire this strategic holding. The grant came with reasonable terms but included the requirement to build a strong house “after the English manner” within ten years, a condition that would shape the castle we see today.

The castle itself is a substantial rectangular structure measuring approximately 18 metres by 8.25 metres, rising two storeys over a basement at its northwest end. A two-storey tower projects from the south angle, whilst a stairs tower containing a newel staircase with pointed doorways extends from the northeast side. The building retains much of its original character, including the wall-walk and stepped crenellations on the parapet, though many features were altered during an eighteenth-century renovation when the windows, external doorways, floors, and roof were replaced. Six chimney stacks, supported by corbels from the first floor, hint at the domestic arrangements within: one heated what was likely the hall or large public room, another warmed a bedroom in the attached tower, whilst the others served various chambers throughout the building. A machicolation above where the original doorway once stood, adjacent to the stairs tower, still marks the castle’s defensive origins.

The castle’s ownership tells a story of Ireland’s turbulent seventeenth century. John Hadsor’s involvement in the 1641 rebellion led to the forfeiture of all his property before his death in 1657, after which the Commonwealth granted the fee-farm to Colonel Thomas Sadler, who sold it to the Brownlow family of County Armagh. Following the Williamite and Jacobite wars, Thomas Clinton, a Jacobite relative of the Brownlows, leased Maghernacloy from Arthur Brownlow; a remarkable figure who managed to sit in both James II’s Catholic Parliament of 1689 and subsequent Protestant parliaments under William and Anne. Arthur was also an Irish scholar who acquired the famous Book of Armagh in 1707 from its hereditary keepers, the MacMoyre family, now housed in Trinity College Dublin. The Clinton family maintained their lease into the nineteenth century, and though the castle was finally abandoned in the 1970s, it found new life after 2000 when it was carefully restored as a dwelling, with archaeological excavations revealing eighteenth-century pottery sherds and confirming that the basement extends beneath the entire structure.