Career
He was the lord of Cappacio, Muro, and Montalbano in the Kingdom of Naples. Captured in 1350 at the siege of Aversa, he was held prisoner by Louis I of Hungary until 1352. He immediately broke the promise by seizing the fortress of Les Baux on 6 April 1355.
This was the Provençal seat of Raymond des Baux, brother and successor of the murdered Robert.
After an unsuccessful attempt at mediation by Walter VI of Brienne and others, local levies besieged the castle, and by July, Robert was compelled to surrender it to its rightful owner. He accompanied the Cardinal to the Battle of Poitiers.
Before the battle, the Cardinal attempted to mediate between the English forces under Edward, the Black Prince and the French forces under John II of France. Robert, like many of the Cardinal"s men, joined the fight on the French side, and was killed there.
This violation of the neutrality which ought to adhere to a churchman and mediator so provoked Edward the Black Prince that he had Robert"s body borne on a shield to the Cardinal as a mocking salute.