Earldom of Ulster

The Earldom of Ulster was an Anglo-Norman lordship in northern medieval Ireland, established by John de Courcy from the conquest of the province of Ulaid in eastern Ulster. It was the most important Anglo-Norman lordship in the north of Ireland. At its greatest extent it extended as far west as the Inishowen peninsula in modern-day County Donegal, which was at one time the power-base of the Northern Uí Néill.