Ralph III, Count of Eu
Raoul I of Brienne was the son of John II of Brienne, Count of Eu and Jeanne, Countess of Guînes.
He succeeded his father as Count of Eu in 1302, and his mother as Count of Guînes in 1332. In 1329, he was named Constable of France, and he also held the office of Governor of Languedoc. The Count of Eu commanded French forces during the opening stages of the Hundred Years' War, as befit his rank of Constable. However, he proved to be a poor commander and "a man of very limited talent", according to Lord Sumption.
In 1315, he married Jeanne de Mello, Lady of Lormes and Château-Chinon. The daughter of Dreux VI de Mello, she was the heiress to a rich Burgundian barony. They had three children:
- Raoul II of Brienne, Count of Eu and Guînes
- Jeanne, Lady of Château-Chinon, married first in 1342/3 Walter VI of Brienne, married second in 1357 Louis I d'Évreux, Count of Étampes
- Marie, d. young