The earldom, and the viscounty of the United Kingdom, being limited to heirs male, became extinct, but the barony, being to heirs general, passed to his daughter, Sophia Charlotte (1762-1835), who married the Hon.
It was conquered by the Vascones in the 6th century, and in 819 became a viscounty dependent on the dukes of Aquitaine - a feudal link which was broken in the 11th century, when the viscounts ceased to acknowledge any suzerain.
As Gaston left only daughters, the viscounty passed at his death to the family of Foix, from whom it was transmitted through the houses of Grailly and Albret to the Bourbons, and they, in the person of Henry IV., king of Navarre, made it an apanage of the crown of France.
When Gaston-Phoebus wished to establish a regular annual hearth-tax (fouage) in the viscounty, he convoked the deputies of the three estates in assemblies called accts.
Argentan was a viscounty from the 11th century onwards; it was often taken and pillaged.