In either 888, when his father was crowned King of France, or 889, when his father was crowned King of Italy, Guy was granted the Duchies of Spoleto and Camerino. Though his father never secured the French kingdom, he did maintain his Italian crown and thus happily divested himself of his responsibilities in Spoleto itself, the hereditary possession of his family. Guy was a capable warrior and leader. He conquered Benevento from the eastern Romans and made himself prince there (895). He offered the regency of his conquered principality to Guaimar I of Salerno, the husband of his sister Itta, but Guaimar was captured en route to Benevento by Adelfer, the gastald of Avellino. Guy had to go down and besiege Avellino to get his release.
After reigning in Benevento for a year and eight months, Guy travelled to Rome to meet the Emperor Lambert. He was murdered on the Tiber by agents of Alberic, who seized Spoleto and set himself up as duke.
- His parentage is highly disputed. He is referred to as a son of Guy III of Spoleto and Ageltrude"Archived copy". Archived from the original on 2007-10-01. Retrieved 2009-04-29.CS1 maint: archived copy as title (link) and also of one Conrad, count of Lecco.Guaimar I of Salerno He is called both a first cousin and a brother of Lambert II of Spoleto."Archived copy". Archived from the original on 2007-10-01. Retrieved 2009-04-29.CS1 maint: archived copy as title (link) Thus, his exact relationship to the emperors Guy and Lambert and to the Empress Ageltrude is uncertain.
- Caravale, Mario (ed). Dizionario Biografico degli Italiani: LX Grosso – Guglielmo da Forlì. Rome, 2003.
- Caravale, Mario (ed). Dizionario Biografico degli Italiani: LXI Guglielmo Gonzaga – Javobini. Rome, 2003.
- Lexikon des Mittelalters: Wido IV. Herzog von Spoleto (882/83-897).
| Duke of Spoleto
| Margrave of Camerino|
Title last held byUrsus
| Prince of Benevento