Early Life
John FitzWilliam was born to
William Fitzwilliam and
Maud ___ (whose surname was possibly, but probably not, Deincourt), most likely in the 1290s.
Note that this generation is skipped in
Burke's Peerage (99th Edition, Fitzwilliam), but is shown in
Burke's Extinct Peerage.
Death
Baildon1 says that he most likely died of the Black Death on the 10
th of August 1349:
The inquisition as to his Yorkshire property was held August 4, 1350. He died seised of the manors of of Darthyngton [Darrington], Emley and Sprotborough, and of a tenement in Dalton [probably Dalton in the parish of Kirkheaton]; the capital messuages of the three manors are stated to be ruinous, and all the lands are described as lying waste for lack of tenants, owing to the pestilence. John, his son and heir, was aged 22 years and 6 months.
Footnotes
[1] Baildon and the Baildons, a History of a Yorkshire Manor and Family, by W Paley Baildon, Volume 1, page 356