We know that in the late twelfth century the English first landed and began their conquest. In 1178 John de Courcey advanced into Machaire Conaille (the plain of Louth) to plunder it and exact a prey of a large number of cattle.
On his return to Downpatrick he encamped for a night at Glionn-Righe (our own district today) and here he was attacked by Murrough O’Carroll, Lord of Oirghiall (Oriel) and Cooley at the head of a large native force.
The English were defeated and driven into the river. As the tide on the river was rising, great numbers of them were drowned in attempting to cross from the Oirghiall (Down) to the Ulidia (
Their loss amounted to 450 men while the victorious Irish lost only 100, among whom was the leader O’Hanvy, Lord of Hy-Meith-Macha.
It was probably after this terrible defeat that De Courcey erected the castle at the
… Bagenal Grant …