Guillaume was a monk in the
Abbey of St Martin, Autun, of which he became abbot. Around 1375, he became the
abbot of Saint-Seine, a position he held until 1379. He was named
bishop of Autun on 13 February 1379 by
bulls of
Pope Clement VII and was appointed
bishop of Beauvais on 26 August 1387. He was not there long, as on 29 March 1389 he was named archbishop of Rouen, although he did not take possession of the archdiocese before November 1389 (the
Gallia Christiana dates his solemn entry to 1393; he was however present at the manor of
Déville as of August 1389). He attended the first embassy with the new
Pope Benedict XIII in 1394. He was also present at the convent of the
Celestines of
Avignon during the burial of Clement VII in September 1401. He celebrated mass in the
Sainte-Chapelle at the coronation of Queen
Isabeau of Bavaria, wife of King
Charles VI of France. He was also present in Rouen during the translation of the relics of
Saint Louis. He died on 18 February 1407 in the
hôtel of the archbishops of Rouen in Paris and was buried in the Abbey of Saint-Seine in an imposing tomb with a
recumbent effigy. ==References==