Isabel de Clare, suo jure 4th Countess of Pembroke and Striguil (c. 1172 – 11 March 1220), was an Anglo-Norman and Irish noblewoman descended from Aoife Macmurrough and Richard de Clare and one of the wealthiest heiresses in Wales and Ireland. She was the wife of William Marshal, 1st Earl of Pembroke, who served three successive kings as Marshal of England. Her marriage had been arranged by King Richard I.
Family inheritance
Isabel was one of two known legitimate children of Earl Richard "Strongbow". Isabel may have been older than her brother Gilbert, who was born in 1173 but died a teenager soon after 1185, at which point Isabel became the heir to her parents' great estates in England, Wales and Leinster. Her mother was the daughter of Diarmait Mac Murchada, the deposed King of Leinster and Mór_Ní_Tuathail. The latter was a daughter of Muirchertach Ua Tuathail and Cacht ingen Loigsig. The marriage of Strongbow and Aoife took place in August 1170, the day after the capture of Waterford by the Cambro-Norman forces led by Strongbow.
Isabel's paternal grandparents were Gilbert de Clare, 1st Earl of Pembroke, and his wife Isabel de Beaumont. Deprived of his father Gilbert's estate of Pembrokeshire by the king in 1153 when he succeeded as a child, Richard Strongbow continued to assert he was an earl, but took his title as Striguil (the Welsh name for the lordship of Chepstow, the centre of his estates in the southern March of Wales). The earldom of Pembroke was not forgotten, however, and in 1199 it was recreated and awarded to Isabel's husband, William Marshal, undoubtedly on the basis of Isabel's hereditary claim to it. In this way, Isabel could be said to be the successor in the earldom of Pembroke to her grandfather Gilbert, the first earl, especially as her husband before 1199 was meticulous in referring to her as 'Countess Isabel'.
Isabel was described as having been "the good, the fair, the wise, the courteous lady of high degree". She allegedly spoke French, Irish and Latin. After her brother Gilbert's death, Isabel became one of the wealthiest heiresses in the kingdom, owning besides the titles of Pembroke and Striguil, much land in Wales and Ireland. She also had a hereditary claim on the numerous castles on the inlet of Milford Haven, guarding the St George's Channel, including Pembroke Castle. She was a ward of King Henry II, who carefully watched over her inheritance, and who we find in 1189 had confided her to the keeping of Ranulf de Glanville chief justiciar of England.
Marriage
The new King Richard I arranged her marriage in August 1189 to William Marshal, regarded by many as the greatest knight and soldier in the realm. Henry II had promised Marshal he would be given Isabel as his bride, and his son and successor Richard upheld the promise one month after his accession to the throne. At the time of her marriage, Isabel was residing in the Tower of London in the protective custody of the Justiciar of England, Ranulf de Glanville. Following the wedding, which was celebrated in London "with due pomp and ceremony", they spent their honeymoon at Stoke d'Abernon in Surrey which belonged to Enguerrand d'Abernon.
Marriage to Isabel elevated William Marshal from the status of military captain and knight into one of the richest men in the kingdom. He would serve as Lord Marshal of England, four kings in all: Henry II, Richard I, John, and Henry III. Although Marshal did not become Earl of Pembroke until 1199—a revival of the title by King John as an act of favour—he nevertheless assumed overlordship of Leinster in Ireland and the Marcher lordships of Chepstow and Usk with Isabel's many other estates in several English counties, which belonged to her father's and her own earldom of Striguil.
Marshal and Isabel did not sail to Ireland till 1200, after taking possession of Pembroke. He left her behind him on his return to England. She may have ruled Leinster in his absence till as late as 1203, with as her seneschal a Wiltshire knight, Geoffrey fitz Robert, who was married to Isabel's aunt, Basilia de Clare, a sister of Strongbow. Isabel is credited with playing a major part at this time in the foundation of the borough known as New Ross. Isabel was again left to rule Leinster in 1207-8 during her husband's house arrest at the court of King John when, though pregnant, she successfully led the campaign which defeated the rebel barons of the province.
The marriage was happy, despite the vast difference in age between them. William Marshal and Isabel produced a total of five sons and five daughters.