William I de Forz(d.1195) (Latinised to de Fortibus) was a minor Anglo-Norman noble, from Fors in Poitou. He became jure uxoris 2nd Earl of Albemarle(or Aumale) following his marriage to Hawise, sole heiress of William le Gros, 1st Earl of Albemarle.[1]
Philip Augustus took control of Aumale(also known as Albemarle) in the 1190s, thus depriving the Anglo-Norman Earls of Albemarle of their continental holdings.
William II de Forz, 3rd Earl of Albemarle was their son, and is also known by the same name.
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".[2] It 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". Thus perhaps would be avoided the somewhat undignified name of "William By Chance". Thus the name in French should in theory be "William de Fors/Forz" (where de is the French particulier "of/from") & in Latin "Willelmus de Fortibus" (where de is the Latin preposition "from" taking the ablative). The seal of William III de Forz, 4th Earl of Albemarle shows his name in the Latinised form "(Sigillum) Willelmi de Fortibus" (Willelmus being in the genitive case -i).