Looking for information on Frederick de Warenne (c10570c1104)brother of William de Warenne. I found several web pages but none have any good sources. can anyone tell me which William de Warenne was his brother and where I can verify his dates and information. Thank you

No doubt this is the 'Frederick, brother of William de Warenne' mentioned in the Domesday Book. First, Frederick was his brother-in-law not his brother. At that time your wife's brothers were considered your own brothers when you married; much more so than today. Secondly, chroniclers and clerics sometimes used the same term for both. Frederick, who left his lands in East Anglia to his sister's husband was Frederick of Oosterzele-Scheldewindeke in Flanders. His sister was William de Warenne's first wife, Gundred. Their brother was Gerbod, Earl of Chester while the father of all three siblings was another Gerbod, advocate of St. Bertin Abbey in Flanders. Frederick was killed circa 1070, by Hereward the Wake. The two brothers, Gerbod and Frederick, came to England with the Conqueror in the Flemish contingent while their sister, Gundred, prior to her marriage, may have been a lady in waiting to Matilda of Flanders. It’s also thought that Gundred (and by extension Gerbod and Frederick) and Matilda were distantly related through the counts of Flanders. I can give you sources if you want them. Jay

Jay, I would be very interested in the sources, thanks, Jim.

Here is the source list for Frederick:

10. David C. Douglas, William The Conqueror, University of California Press, Berkeley & Los Angeles, 1964, p. 267.
11. Elizabeth van Houts, “Hereward and Flanders,” Anglo-Saxon England,, Volume 28, 1999, p. 215.
12. Elisabeth van Houts, “Frederick, Brother-in-Law of William of Warenne,” Anglo-Saxon England, Vol. 28, Cambridge University Press, 1999, pp. 218-220.
13. Freda Anderson, “Uxor Mea": The First Wife of the First William of Warenne,” Sussex Archaeological Collections, Sussex Archaeological Society, Vol. 130, 1992, p. 107.
14. David C. Douglas, William The Conqueror, University of California Press, Berkeley & Los Angeles, 1964, p. 267 (states 1079 which is almost certainly a misprint for 1069).
15. Elisabeth van Houts, “Epitaph of Gundrada of Warenne,” Nova de Veteribus, K.G. Saur, 2004, p. 372 (states c. 1070).
16. Early Yorkshire Charters, ed: William Farrer, Charles Travis Clay, The Yorkshire Archaeological Society, Volume VIII, 1949, p. 45.

Jay

One more source for Frederick (of Oosterzele):

K.S.B. Keats-Rohan, Domesday People, Boydell Press, 1999, p. 40

Here it states that by 1086 Frederick, the brother of Gerbod the Fleming (Earl of Chester) was dead and Gerbod had long since returned home, that lands in St. Omer were not held by William de Warenne. On p. 480, it connects the wife of William de Warenne, Gundreda as sister of Gerbod the Fleming, Earl of Chester. So while he is not mentioned on p. 280, taken with p. 40 it shows Frederick's connections to his brother Gerbod, and sister, Gundrada, and to his brother in law, William de Warenne. Hope this helps.

Jay