ÉPERNON, a town of northern France in the department of Eure-et-Loir, at the confluence of the Drouette and the Guesle, 17 m. N.E. of Chartres by rail. Pop. (1906) 2370. It belonged originally to the counts of Montfort, who, in the 11th century, built a castle here of which the ruins are still left, and granted a charter to the town. In the 13th century it became an independent lordship, which remained attached to the crown of Navarre till, in the 16th century, it was sold by King Henry (afterwards King Henry IV. of France) to Jean Louis de Nogaret, for whom it was raised to the rank of a duchy in 1581. The new duke of Épernon was one of the favourites of Henry III., who were called les Mignons; the king showered favours upon him, giving him the posts of colonel-general in the infantry and of admiral of France. Under the reign of Henry IV. he made himself practically independent in his government of Provence. He was instrumental in giving the regency to Marie de’ Medici in 1610, and as a result exercised a considerable influence upon the government. During his governorship of Guienne in 1622 he had some scandalous scenes with the parlement and the archbishop of Bordeaux. He died in 1642. His eldest son, Henri de Nogaret de la Valette, duke of Candale, served under Richelieu, in the armies of Guienne, of Picardy and of Italy. The second son of Jean Louis de Nogaret, Bernard, who was born in 1592, and died in 1661, was, like his father, duke of Épernon, colonel-general in the infantry and governor of Guienne. After his death, the title of duke of Épernon was borne by the families of Goth and of Pardaillan.