1911 Encyclopædia Britannica, Volume 8… (1911)
“ In the 10th century Dreux was the chief town of a countship, which Odo, count of Chartres, ceded to king Robert, and Louis VI. gave to his son Robert, whose grandson Peter of Dreux, younger brother of Count Robert III., became duke of Brittany by his marriage with Alix, daughter of Constance of Brittany by her second husband Guy of Thouars. By the marriage of the countess Jeanne II. with Louis, viscount of Thouars (d. 1370) , the Capetian countship of Dreux passed into the Thouars family. ”
