William, Count of Mortain

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Guillaume de Mortaigne, Comte de Mortaigne, 3rd Earl of Cornwall

Also Known As: "de Burgh", "William", "Earl E. Cornwall", "Count Guillaume", "comte de Mortain", "William Earl De Mortaigne Earl Of Cornwall"
Death: circa 1140 (71-89)
Bermondsey, England (United Kingdom)
Immediate Family:

Son of Robert de Mortagne, Earl of Cornwall and Maud Matilda de Montgomery, Comtesse consort de Mortain
Husband of Adelise, comtesse consort de Mortain
Brother of Agnès de Mortagne; Hertiginna av Toulouse Emma de Mortain, comtesse consort de Toulouse; Denise de Mortain; Annora de Mortaigne and Robert, comte de Mortain
Half brother of Mabel de Châteauneuf; Hugo de Chateuaneuf; Aldhelm de Mortagne; Robert de Mortain and Lucia de Mortagne

Managed by: Bernard Raimond Assaf
Last Updated:

About William, Count of Mortain

brief biography

2nd or 3rd Earl of Cornwall Earl of Mortain/Mortaigne/Moreton (in Normandy)

William rebelled and was captured at the battle of Tinchebrai in 1106. He lost the family lands and was long held in London. He became a Cluniac monk at Bermondsey and probably had no issue.



William, Count of Mortain (1074–1120) was the son of Robert, Count of Mortain, the half-brother of William I of England.

He joined the rebellion of Robert Curthose against Henry I of England, and was captured at the Battle of Tinchebrai and stripped of his lands. William spent the rest of his life in captivity, dying without issue.

Take due notice

He was not married to Isabel FitzRichard, {Fictional}


Some 17th, 18 and 19th Century genealogists created a completely fictitious family tree for William and Hubert de Burgh, linking in William Fitz Aldelm, Robert of Mortain, Charlemagne et al. The whole theory was demolished by JH Round in "Feudal England" (1909), and there is a further discussion in Clarence Ellis's "Hubert de Burgh A Study in Constancy" (1952). All academic papers on the de Burgh family of Norfolk accept that the family was so minor that we can't even be confident as to who the father of William and Hubert de Burgh was.

  • https://en.wikipedia.org/wiki/William,_Count_of_Mortain
  • https://www.wikitree.com/wiki/Conteville-68 cites
    • Cockayne et al., Complete Peerage, 2nd ed., vol. 3, under "Cornwall", pp. 428-429.
    • I.J. Sanders (1960) English Baronies, under "Berkhamstead", p.14; under "Launceston", p. 60; under "Pevensey", p. 136.
  • https://en.wikipedia.org/wiki/Battle_of_Tinchebray The Battle of Tinchebray (alternative spellings: Tinchebrai or Tenchebrai) took place on 28 September 1106, in Tinchebray (today in the Orne département of France), Normandy, between an invading force led by King Henry I of England, and the Norman army of his elder brother Robert Curthose, the Duke of Normandy.[2] Henry's knights won a decisive victory: they captured Robert, and Henry imprisoned him in England (in Devizes Castle) and then in Wales until Robert's death (in Cardiff Castle) in 1134.[3]
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William, Count of Mortain's Timeline

Age 80
Bermondsey, England (United Kingdom)