In 1148, de Warenne inherited her father's lands and the earldom of Surrey and was married to William of Blois, the younger son of King Stephen, that year. The marriage occurred at a critical moment in The Anarchy as part of the king's attempt to control the de Warenne lands. The couple did not have any children and after William's death in 1159, William X, Count of Poitou sought her hand in 1162/3, but Thomas Becket refused a dispensation from affinity on the grounds of consanguinity.
In April 1164, the countess married Hamelin Plantagenet, the half-brother of King Henry II, who became jure uxoris Earl of Surrey. Hamelin died in 1202 and the countess a year later. She was buried alongside him in the chapter house of Lewes Priory.
|Offspring of Isabel de Warenne and Hamelin de Warenne (c1129-1202)|
|William de Warenne (1166-1240)||1166||1240|| Maud Marshal (1192-1248)|
|Adela de Warenne (c1170-c1218)||1170||1218|| John of England (1167-1216)|
|Isabel de Warenne (?-1234)|| |
|Maud de Warenne (c1162-c1212)||1162||1212|| Henri Hastings (-c1183)|
Common ancestors of Isabel de Warenne (1130-1202) and William of Blois (c1137-1159)