William of Hauteville formed the second core of his possessions and differentiated himself from Rainulf I of Aversa, head of the territories of Campania.

All the barons present offered a tribute as a vassal to Guaimar, which recognized William I of Hauteville as the first to receive the title of Count of Apulia.

In 1047, Drogo of Hauteville was made "count" of Apulia and Calabria by Emperor Henry III, with territories lost by Guaimar IV of the Principality of Salerno.

Salerno remained the capital of this southern Italian political entity for half a century (from 1078 to 1130), the city flourished with the Schola Medica Salernitana, the first medical school in Europe.

He christened William's successor (and brother) Drogo Dux et Magister Italiae comesque Normannorum totius Apuliae et Calabriae and made him a direct vassal of the empire.