[1] Roger's first public act took place at Melfi in 1129, where, though still a child, he accepted the fealty of some rebellious barons along with his father and his younger brother Tancred.

After Ranulf's death (1139), Apulia was secured, but Innocent and his ally, Prince Robert II of Capua, marched on Melfi.

Three days later, on July 25 at Mignano, Innocent confirmed the elder Roger as king, the younger as duke, and the third son, Alfonso, as prince of Capua—officially severing Robert from his support.

Next, Duke Roger took the city of Naples into his possession and made it an integral part of the kingdom, ending the republican government which had continued after Sergius' death.

In 1140, after the promulgation of the king's Assizes of Ariano, the first ducats were minted bearing an effigy of the young duke in battledress beside his father, with their hands on the Cross.