Lordship of Ulster

John de Courcy (also John de Courci ) (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.

John de Courcy, of Stoke Courcy, in Somerset, came to Ireland around the year 1171 as part of the Norman invading forces, brought in as mercenaries working for Diarmaid Mac Murchadha, the ousted King of Leinster, to help him regain his position as king. De Courcy's great-grandfather, Richard de Curci is named in the Domesday Book. His grandfather, William de Curci I, married Emma of Falaise. His father, William de Curci II, married Amice, of Brittany, and died about 1155, leaving the family estates in Somerset and elsewhere in England to his son, William de Curci III, John's elder brother.

John was very ambitious and wanted lands for himself. He decided to invade the north of Ireland which was controlled by Irish dynasties. In early January 1177 he assembled a small army of 22 knights and 300 foot soldiers and marched north, at the rate of thirty miles a day. They skirted the back of the Mourne Mountains and took the town of Dún Dá Leathghlas (now Downpatrick) by surprise. After two fierce battles, in February and June 1177, de Courcy defeated the last King of Ulaid, Ruaidhrí Mac Duinnshléibhe.

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