Succeeded to the command of the military forces in Jersey when the Governor Dru de Barentin was slain.
Edward III's pursuit of the French Crown brought war with France in its train, and the islands were again drawn into the conflict.
Sir Renaud led a Jersey fleet, assisted by the English, to regain Guernsey in 1356 and helped to drive out the French from that island.
A trial ensued, when the angry widow stated that her husband had been done to death, "out of ancient enmity and their own malice", and the Jerseymen implicated were banished.
Sir Renaud de Carteret and Ralph Lempriere, who had been leaders in the siege, challenged the verdict and were imprisoned in Castle Cornet, where they had a hard time at the hands of the Guernseymen until released by the King's pardon.