[4] Around 1035/7, Drogo journeyed to Southern Italy with his brothers William Iron Arm and Humphrey, to strengthen the ranks of Rainulf Drengot, Count of Aversa, the first Norman mercenary lord who had been granted a fief.

Under Guaimar's authority, Norman and Lombard forces served the Byzantine army in an attempt to conquer Sicily from the Saracens.

[3][4] During said rebellion, Drogo's brother William Iron Arm had managed to keep the Normans under his control, and was the key to many victories.

[1][4] When William Iron Arm died childless in 1046, Drogo succeeded him as Count of Apulia after fighting for the title with Peter I of Trani.

Drogo's legitimacy grew significantly when Emperor Henry III came to Southern Italy in 1047: Drogo paid homage to the Emperor on 3 February, and Henry III confirmed the possession of his territories and invested him as "Dux et magister totius italiae comesque Normannorum totius Apuliae et Calabriae", which translates to "Duke and master of all of Italy, and Count of all the Normans in Apulia and Calabria".

If this is the case, Drogo probably released Richard after the Aversans expelled Bellabocca, as keeping him prisoner no longer served a purpose.

[5] Towards the end of his reign, Drogo met with Pope Leo IX, when he came to Southern Italy to restore the Libertas Ecclesiae under Henry III's directives.

However, as he was returning from the meeting with the Pope, he was assassinated along with several of his followers on Saint Lawrence's Day (10 August) of 1051, while he was entering the chapel of his castle at Monte Ilario, near Bovino, to attend mass.