William I, Count of Boulogne

William I of Blois (c. 1137 – 11 October 1159) was Count of Boulogne (1153–1159) and Earl of Surrey jure uxoris (1153–1159). He was the second son of Stephen, King of England, and Matilda I, Countess of Boulogne.[1]

William I
Count of Boulogne
Reign17 August 1153 – 11 October 1159
PredecessorEustace IV
SuccessorMary I
Bornc. 1137
Died11 October 1159 (aged c. 22)
Toulouse, France
SpouseIsabel de Warenne, 4th Countess of Surrey
FatherStephen, King of England
MotherMatilda I, Countess of Boulogne

When his elder brother, Eustace IV of Boulogne, died in 1153, William was passed over in the succession to England. His father instead conceded the throne to the young Henry Plantagenet (son of his cousin, Matilda) by the Treaty of Wallingford/Winchester to end the war between Stephen and Henry, of which both sides were growing weary. The new King Henry initially allowed William of Blois to retain the earldom of Surrey jure uxoris (in right of his wife).[2]

However, Gervase of Canterbury asserts a plot against Henry's life was discovered in 1154 among some Flemish mercenaries. The plan was to assassinate Henry in Canterbury, and allegedly William of Blois had knowledge of this plot or was in connivance with the mercenaries. Whatever the truth, Henry fled Canterbury and returned to Normandy.

William of Blois had married Isabel de Warenne, 4th Countess of Surrey, in 1148.[1] They had no children. He died, in 1159, of disease near Toulouse, and was buried at the Poitevin abbey of Montmorel. He was succeeded as Count of Boulogne by his sister, Mary I. His widow remarried to Hamelin Plantagenet.



  1. ^ a b Van Houts 2004, p. 112.
  2. ^ Wilfred Lewis Warren (1973). Henry II. University of California Press. p. 364. ISBN 978-0-520-02282-9.


  • R. H. C. Davis (1967), King Stephen
  • Thomas K. Keefe, "William, earl of Surrey (c. 1135–1159)", Oxford Dictionary of National Biography, 2004
  • Van Houts, Elisabeth (2004). "The Warenne View of the Past, 1066-1203". In Gillingham, John (ed.). Anglo-Norman Studies XXVI: Proceedings of the Battle Conference 2003. The Boydell Press.CS1 maint: ref=harv (link)
Preceded by
Eustace IV
Count of Boulogne
Succeeded by
Mary I
Preceded by
Count of Mortain