Wilhelm’s half brother, Prince Bishop Lorenz von Bibra of Würzburg, in 1487 wrote a letter of introduction to Pope Innocent VIII for Wilhelm who was being sent to the Vatican as emissary of Archbishop Herman of Cologne.
NOBILIS ET STRENN(uus) D(ominus) GULIELMUS DE BIBRA EQUES AUREUS DUCATU FRANCIAE ORIENTAL(is) ORIUNDUS SERENISS(imi) D(omini) FRIEDERICI III CAESARIS INVICTISS(imi) ET MASSI= MILIANI EIUS NATI, INCLITI ROMANORUM REGIS CONSILIAR(ius) AD S(anctum) D(ominum) N(ostrum) INNO= CENTIUM PAP(am) VIII ORATOR ET NUNTIUS ATQUE REVER[endissimi) D(omini) HERMANNI ARCHI(e)PI(scopi) COLONIENSIS PRINCIP(is) ELECTOR(is) MAGIS(ter) CURIAE CONSILIAR(ius) COMPLETA LEGATIONE EX RO(ma) DOMUM REGREDITUR(us) OBIIT IN HAC INCLITA URBE VERONAE DIE 28.
and his son Maximilian, the well-known Roman king, representative and envoy to our Holy Lord Innocent VIII, as well as Court Administrator and councilor of the Archbishop of Cologne, Elector Hermann.
After completing his mission on the way home from Rome, he died in the famous city of Verona on August 28, 1490.
At the feet of the representation: “Out of piety and grace, the Pellegrini family gave me a grave in their chapel just for me.