Sir John de Courcy (1150–1219) was an Anglo-Norman knight who arrived in Ireland in 1176. From then until his expulsion in 1204, he conquered a considerable territory, endowed religious establishments, built abbeys for both the Benedictines and the Cistercians and built strongholds at Dundrum Castle in County Down and Carrickfergus Castle in County Antrim.

Carrickfergus Castle is a Norman castle in Northern Ireland, situated in the town of Carrickfergus in County Antrim, on the northern shore of Belfast Lough. Besieged in turn by the Scottish, native Irish, English, and French, the castle played an important military role until 1928 and remains one of the best preserved medieval structures in Northern Ireland. It was strategically useful, with 3/4 of the castle perimeter surrounded by water. Today it is maintained by the Department for Communities as a state care historic monument, at grid ref: J4143 8725.