According to Amatus of Montecassino, Hervé and other Norman mercenaries fought for the Byzantine Empire under George Maniakes against the Muslims in Sicily from 1038 to 1040.
At about 1050, he appears as the leader of the Norman mercenaries under Nikephoros Bryennios the Elder and one of the Greek's two chief lieutenants.
From there, he gathered a following of 300 Normans, and in the spring of 1057 he marched into eastern Asia Minor, around Lake Van.
[1] There, he possibly aimed to set up a state for himself and entered into wars with the Armenians and the Seljuk Turks.
[2] Hervé was shipped back to Constantinople in chains, but there he was apparently reconciled to the Byzantine emperor: a surviving seal records his having received the title of magistros, and the positions of vestiarites and stratelates of the East in the army of Emperor Isaac I Komnenos (r.