William Marshal (c.1146-1219), called the Marshal and 4th Earl of Pembroke, soldier and administrator, was born a younger son who had risen through the ranks of the Norman hierarchy because of his prowess as a soldier, skill as a courtier, and success in knightly tournaments. An advantageous marriage in 1189 to the heiress Isabel de Clare (c.1171-1220), daughter of Richard fitz Gilbert de Clare known as Strongbow and his wife Aoife Mac Murchada, enabled Marshal to join an elite group that held great swathes of lands in Wales, Ireland and also in Normandy.
A notable soldier, he had travelled extensively in Europe going east as far as the Kingdom of Jerusalem. Before his marriage and during the 1180s Marshal served in the royal household where he began to accumulate wealth. On the death of his elder brother, Marshal had inherited the family’s lands and, when King John came to the throne 1199, he was finally granted the lands and title of earl of Pembroke.
In the process of extending their feudal lordships in Ireland the Marshals had, over just two generations, greatly influenced the future shape of Leinster. During that time they built castles, brought in settlers, founded boroughs, and endowed religious houses. When Marshal went to claim his Pembrokeshire lands in 1201 he crossed over to his lands in Leinster. In 1207, having fallen out of favour with the king, he retired to Ireland with his military household in attendance.
He remained here for a period of six years, with just two brief visits across the Irish Sea when summoned by King John. During that time he organised his Irish estates and it is likely that he was also building at Kilkenny. When he departed from Ireland, his wife Isabel de Clare, who was also a great magnate in her own right, took charge of his estates.