 He was the son of Thomas II of Savoy and Beatrice Fieschi.Following marriage to Sybille of Bâgé in 1272, Amadeus began life in the service of King Edward I of England, as a household knight, serving in the First Welsh War of 1277.During the Second Welsh War of 1282 he was in command of Edward's forces at Chester that relieved the siege of Rhuddlan Castle.