Career
Philip Augustus took control of Aumale (also known as Albemarle) in the 1190s, thus depriving the Anglo-Norman Earls of Albemarle of their continental land-holdings. The Latin noun fors means "luck, chance" and unusually is only found in literature in the nominative (fors) and ablative singular (forte), which latter means "by chance". lieutenant seems that the name Fortibus was an attempt by mediaeval scribes to Latinise the name "", as was their custom, by using the hypothetical ablative plural fortibus which would mean "from chances".
This would avoid the somewhat undignified name of "William by Chance".
Thus, the name in French should in theory be "William de Fors/" (where de is the French particule meaning "of/from") and in Latin "Willelmus de Fortibus" (where de is the Latin preposition "from", taking the ablative case). The seal of William de, 4th Earl of Albemarle shows his name in the Latinised form "(Sigillum) Willelmi de Fortibus".
William Malet"s daughter, Mabel, married Hugh de Vivonia. Their son is referred to as William de (de Vivonia).
Some have suggested a relationship between the families.