Aimery first entered Italy in the service of Charles I of Anjou, who had been granted the Sicilian crown by Pope Clement IV in 1265.
[1] By 1289, Aimery had so distinguished himself that he was put in command of the Guelph troops massed to attack the Ghibellines of Arezzo.
During that campaign, the two armies met at the Battle of Campaldino and Aimery won the victory on which his reputation rests.
[2] He conquered most of the Aretine countryside, taking many castles by storm, from Rondine [it] to the gates of Arezzo itself.
The campaign was nevertheless a success and Aimery was received triumphantly upon his return to Florence, where he was the representative of Charles II of Naples.