John (1167–1216), lord of Ireland and later king of England, was born at Oxford on 24 December 1167, the fifth and youngest son of Henry II (qv), king of England, and his wife Eleanor of Aquitaine. He was created lord of Ireland by his father in 1177, with the intention of making him king of Ireland when a crown was secured from the pope. He was sent to Ireland in the spring of 1185, landing in Waterford (25 April). His mission was carefully planned by his father, and he was accompanied by a group of capable administrators and soldiers. The purpose was to strengthen the administration of the lordship of Ireland and bring the colonists back under royal control. John stayed in Ireland till 17 December 1185, travelling from Waterford to the borders of the kingdom of Thomond and northward to Dublin, where he spent the summer and autumn. While his expedition had some minor successes (most notably the fortification of the king's demesne in Waterford), these were greatly outweighed by John's alienation of the colonists’ Gaelic allies and his complete inability to bring the colonists, led by Hugh de Lacy (qv), under his control. The most lasting effect of the 1185 expedition was the introduction of a new wave of colonists, men such as Theobald Walter (qv), who soon became integrated into the expanding colony.
During the reign of Richard I, John was responsible for the governance of the lordship of Ireland and used the opportunity to override the rights of Isabella de Clare (Isabella Marshal (qv)) and her husband William Marshal I (qv), earl of Pembroke, by making grants within their lordship on his own authority without consulting them. John's authority in Ireland was revoked in 1193–4 for his part in a rebellion against his brother, and as part of the settlement the king forced him to undo some of the grants he had made in Leinster. On John's accession to the throne (1199), the lordship of Ireland was reunited with the English crown and John started the process of enforcing royal authority in Ireland. While he was prepared to boost the position of some magnates (as when he recreated the liberty of Thomond for William de Braose (qv) in 1201), in general he took a firm line with the great magnates of Ireland, especially after the loss of Normandy. John de Courcy (qv), William Marshal (qv), Hugh de Lacy II (qv), whom John had made earl of Ulster, and Walter de Lacy (qv), lord of Meath, all fell foul of the king in the first decade of his reign, and those that managed to return to his good graces were forced to accept new charters for their lordships that significantly lessened their independence. John's determination to restore and expand the royal administration of the lordship can be seen in his appointment of John de Grey (qv), bishop of Norwich, one of his most capable officers, as justiciar (June 1208). The king's order to arrest William de Braose in 1208 was resisted by the magnates of Ireland.
When the rebellion of de Braose and the de Lacys was linked to the possibility of invasions from Scotland and France in the summer of 1209, the king determined that a personal visit to Ireland with an army was needed to impress his authority on his subjects in Ireland. He landed near Waterford (20 June 1210) with an army consisting of the feudal levy and Flemish mercenaries, some 700 ships, and almost twice as many men as his father had mustered in 1171. Furthermore he was joined immediately by the justiciar with his own troops from Munster and Desmond. With this overwhelming force John progressed through the lordship, taking the submissions of Gaelic and Anglo-Irish alike. His only military action was to drive Hugh de Lacy out of Ulster in a campaign that lasted less than two weeks.
Even more important than this crushing military victory was the care with which the king established and enhanced his administrative authority in Ireland. He firmly established all the organs of government found in England in the lordship – the exchequer, the judiciary, and all the writs of the common law – and backed these administrative reforms with military force where necessary. He had ordered the construction of Dublin castle in 1204, and now proceeded to order the construction of castles along the borders of Connacht, most importantly at Athlone. The need for these new fortifications was clear, as John's relations with Cathal Mór Crobderg Ua Conchobair (qv) (d. 1224), king of Connacht, and Áed O'Neill (qv) (d. 1230), king of Tír Eógain, were deteriorating even as he left Ireland (25 August 1210), and John de Grey would launch invasions of both provinces in 1213. While in Ireland, John had pursued policies that established his authority over all of his subjects, both Gaelic and Anglo-Irish, though the realities of the situation were such that his control over the greatest of the Gaelic lords was still tenuous. But a measure of his success was the solidarity with which his magnates in Ireland stood behind him during the last years of his reign, in particular Marshal and de Lacy, who recovered the king's favour through good service and because he needed them.
King John died at Newark during the night of 18/19 October 1216. He was buried in Worcester cathedral.