Leinster, which takes its name from a people known as the Laigin, was, in the early medieval period, dominated by two dynasties, the Uí Dúnlainge, in the plains of Kildare, and the Uí Chennselaig, whose capital was at Ferns, Co. Wexford. By the time of the Anglo-Norman invasion the latter, who had come to exercise overlordship of the Viking town of Dublin, were dominant, and were led by Dermot MacMurrough, who initiated the invasion in an effort to recover his kingship. Dermot's daughter married the leader of the invaders, Strongbow (Pembroke), who succeeded to Leinster after him, making it the heartland of the new Anglo-Norman colony in Ireland, with Dublin as its capital. Leinster became the most heavily Anglicized part of Ireland, but by the late 13th cent. even the Dublin hinterland was under threat from the resurgent Irish of the Wicklow mountains. In the late medieval period it was dominated by the Anglo-Irish earls of Ormond and Kildare, the latter being masters of the English Pale. The 16th cent. saw renewed English plantation, notably of Laois and Offaly in the 1550s, though a more widespread transference in landownership to English protestants only followed from Cromwell's response to the 1641 rebellion. The province, particularly Co. Wexford, was the focus of the failed 1798 rebellion which led to the Act of Union.

Sean Duffy

Leinster Province in e Republic of Ireland, comprising the counties of Carlow, Dublin, Kildare, Kilkenny, Laoighis, Longford, Louth, Meath, Offaly, Westmeath, Wexford and Wicklow. It is the most populous of Ireland's four provinces, and includes the most fertile farmland. The major city is Dublin. Area: 19,635sq km (7581sq mi). Pop. (1996) 1,924,702.