Constructed in 1210 or 1211 by John Grey, the king’s Justiciar in Ireland, this motte and bailey castle was one of seven fortifications erected to cut off Ulster, which remained under native Irish control, from the province of Connacht. The strategic importance of this river crossing made it an obvious choice for a stronghold, though the Norman occupation proved remarkably brief; by 1213, Irish forces led by Aedh O’Neill had driven the invaders back, and the fortress was likely abandoned.

The motte itself remains an impressive earthwork, rising 5.5 metres high with an oval base measuring roughly 47.5 metres from west-northwest to east-southeast. At its summit, visitors can spot the foundations of a small circular stone structure, possibly a later tower dating to the 16th century, whilst a dramatic depression cuts through the centre of the mound, separating its eastern peak from a lower crescent-shaped platform to the west. The adjoining bailey, a raised rectangular area of about 1,278 square metres, would have housed the garrison and their supplies, protected by an earthen bank whose traces can still be seen along its southwestern edge. Three mysterious low mounds near the bailey’s perimeter add to the site’s archaeological intrigue, their purpose lost to time.

Today, the medieval earthworks share the island with more recent additions; a modern church and its car park have encroached upon parts of the historic site. The fortification’s defensive ditches remain clearly visible, particularly the wide, deep fosse that cuts across from north-northwest to east-northeast, effectively isolating the motte and bailey from the rest of the island. The shoreline shows evidence of deliberate scarping at both the eastern and western ends, testament to the thorough defensive planning that went into this short-lived Norman outpost. Though no stonework from the original castle survives above ground, the earthworks themselves tell a compelling story of conquest, resistance, and the fluid nature of power in medieval Ireland.