Isabel de Clare, suo jure 4th Countess of Pembroke and Striguil (c. 1172 – 11 March 1220), was an Cambro-Norman and Irish noblewoman who was the daughter of 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 four kings as Marshal of England. Her marriage had been arranged by King Richard I. She ruled Leinster as regent during the absence of her spouse in 1200–1203 and in 1207–1208.

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.M. T. Flanagan, "Negotiating across Legal and Cultural Borders; Aífe, Daughter of Diarmait Mac Murchada, King of Leinster, and Marriage, Motherhood and Widowhood in Twelfth-century Ireland and England", Peritia 30 (2019) pp. 72, 85–86, 91

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).M. T. Flanagan, "Negotiating across Legal and Cultural Borders; Aífe, Daughter of Diarmait Mac Murchada, King of Leinster, and Marriage, Motherhood and Widowhood in Twelfth-century Ireland and England", Peritia 30 (2019) pp. 85–86. 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'.D. Crouch, William Marshal, 3rd edition (Abingdon: Routledge, 2016), 83–84, 101–102

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.Turtle Bunbury (2000). History, Heroes and Villains, William Marshall, Earl of Pembroke, 1147–1219Crusader, Templar, Kingmaker. An article. Retrieved 2010-10-29. 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 had her own personal seal, showing her in a dress, long mantle and pointed wimple whilst holding a falcon. A plaster cast of her seal is in the collection at the British Museum.

Isabel was a ward of King Henry II, who carefully watched over her inheritance, and who in 1189 had confided her to the keeping of Ranulf de Glanville, chief Justiciar of England.D. Crouch, William Marshal, 3rd edition (Abingdon: Routledge, 2016) p. 79.

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 still 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 and imbued him with aristocratic prestige.

During the first few months of the marriage Isabel accompanied her husband, whilst he served King Richard I, to Normandy, crossing from Dover to Calais on 11 December 1189. William 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 until 1200, after taking possession of Pembroke. This was the first time she had returned to Ireland since she was a child. Isabel remained in Ireland when her husband returned to EnglandD. Crouch, William Marshal, 3rd edition (Abingdon: Routledge, 2016) pp. 102–105 and while he fought in Normandy during 1202. 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.D. Crouch, William Marshal, 3rd edition (Abingdon: Routledge, 2016) p. 252 Isabel is credited with playing a major part at this time in the foundation of the borough known as New Ross.C. Ó Drisceoil, "New Ross, a town of William Marshal" William Marshal and Ireland ed. J. Bradley and others (Dublin: Four Courts, 2017), pp. 278–280.

She again ruled Leinster in 1207-8 during her husband's house arrest at the court of King John in England when, though pregnant, she successfully led the campaign which defeated the rebel barons of the province led by Meiler FitzHenry.D. Crouch, William Marshal, 3rd edition (Abingdon: Routledge, 2016) pp. 125–131.

William Marshal and Isabel produced a total of five sons and five daughters. Her husband died in 1219.

Widowhood Isabel lived as a widow for only ten months after the death of William Marshal, though it was by no means an uneventful period. She wrote within days to the papal legate and the justiciar of England asking for the prompt delivery of her lands, and on 18 June 1219, the justiciar issued writs ordering local officers to hand over to her control of her inheritance in four English counties and in Ireland.D. Crouch, "Testament and Inheritance: The Lessons of the Brief Widowhood of Isabel, Countess of Pembroke" Law and Society in Later Medieval and England and Ireland, ed. Travis R. Baker (Abingdon: Routledge, 2018), pp. 32–35. Pembroke is not mentioned, which hints that her eldest son may have directly inherited the earldom as it may have been treated as a royal grant to his father, not as part of his mother's inheritance. The marcher lordship of Striguil also came to her.

In July 1219 she was in France, where she successfully negotiated with King Philip Augustus the possession of her Norman inheritance and did homage to him. While there, she and her son opened negotiations with the king for the marriage of the younger William Marshal with his first cousin, a ploy which caused panic at the English court and a counter-offer of marriage to King Henry III's youngest sister Eleanor.D. Crouch, "Testament and Inheritance: The Lessons of the Brief Widowhood of Isabel, Countess of Pembroke" Law and Society in Later Medieval and England and Ireland, ed. Travis R. Baker (Abingdon: Routledge, 2018), p. 34. There is evidence that she made good use of her eldest son as her agent in managing the great estates that were hers to dispose of in the months she had them, both of them stonewalling her late husband's executors to avoid paying the debts he leftD. Crouch, "Testament and Inheritance: The Lessons of the Brief Widowhood of Isabel, Countess of Pembroke" Law and Society in Later Medieval and England and Ireland, ed. Travis R. Baker (Abingdon: Routledge, 2018), p. 35..

As a widow Isabel confirmed grants that had been made by her husband and extended some. She granted a water meadow to the abbey at Caversham and Henley-on-Thames.

In February 1220 Isabel was mortally ill at Chepstow, and on 2 March her son was at Cirencester en route to Wales to attend her deathbed. Tintern Abbey sources give her death as 11 March 1220.D. Crouch, "Testament and Inheritance: The Lessons of the Brief Widowhood of Isabel, Countess of Pembroke" Law and Society in Later Medieval and England and Ireland, ed. Travis R. Baker (Abingdon: Routledge, 2018), pp. 35–36 She was buried in the north choir aisle of the family abbey of Tintern, next to her mother Aoife.M. T. Flanagan, "Negotiating across Legal and Cultural Borders; Aífe, Daughter of Diarmait Mac Murchada, King of Leinster, and Marriage, Motherhood and Widowhood in Twelfth-century Ireland and England", Peritia 30 (2019) pp. 22 and notes 73, 74.

Issue By her marriage she had ten children, five sons and five daughters:

William Marshal, 2nd Earl of Pembroke (11906 April 1231), married (1) Alice de Béthune, daughter of Baldwin of Bethune; (2) 23 April 1224 Eleanor Plantagenet, daughter of King John of England. They had no children. Richard Marshal, 3rd Earl of Pembroke (119116 April 1234), married Gervaise de Dinan. He died in captivity. They had no children. Maud Marshal (119427 March 1248), married (1) Hugh Bigod, 3rd Earl of Norfolk, they had four children; (2) William de Warenne, 5th Earl of Surrey, they had two children. Gilbert Marshal, 4th Earl of Pembroke (119727 June 1241), married (1) Marjorie of Scotland, youngest daughter of King William I of Scotland; by an unknown mistress he had one illegitimate daughter: Isabel Marshal, betrothed to Rhys ap Maelgwn Fychan (son of Maelgwn ap Rhys) Walter Marshal, 5th Earl of Pembroke (c. 1199November 1245), married Margaret de Quincy, Countess of Lincoln, granddaughter of Hugh de Kevelioc, 3rd Earl of Chester. No children. Isabel Marshal (9 October 120017 January 1240), married (1) Gilbert de Clare, 4th Earl of Hertford, whose daughter Isabel de Clare married Robert Bruce, 5th Lord of Annandale, the grandfather of Robert the Bruce; (2) Richard Plantagenet, Earl of Cornwall Sibyl Marshal (c. 120127 April 1245), married William de Ferrers, 5th Earl of Derby; they had seven daughters. Agnes de Ferrers (died 11 May 1290), married William de Vesci. Isabel de Ferrers (died before 26 November 1260) Maud de Ferrers (died 12 March 1298), married (1) Simon de Kyme, (2) William de Vivonia (de Forz), and (3) Amaury IX of Rochechouart. Sibyl de Ferrers, married Sir Franco de Bohun. Joan de Ferrers (died 1267) Agatha de Ferrers (died May 1306), married Hugh de Mortimer, of Chelmarsh. Eleanor de Ferrers (died 26 October 1274), married (1) William de Vaux of Tharston and Wisset, (2) Roger de Quincy, Earl of Winchester, and (3) Roger de Leyburne of Elham. Eva Marshal (1203–1246), married William de Braose, Lord of Abergavenny Isabella de Braose (born 1222), married Prince Dafydd ap Llywelyn. She died childless. Maud de Braose (1224–1301), in 1247, she married Roger Mortimer, 1st Baron Mortimer and they had descendants. Eva de Braose (122728 July 1255), married Sir William de Cantelou and had descendants. Eleanor de Braose (c. 12281251). On an unknown date after August 1241, she married Sir Humphrey de Bohun and had descendants. Anselm Marshal, 6th Earl of Pembroke (c. 120822 December 1245), married Maud de Bohun, daughter of Humphrey de Bohun, 2nd Earl of Hereford. They had no children.