The County of Fézensac was an 8th-century creation on the north-eastern fringes of the Duchy of Gascony following Charlemagne's policy of feudalisation and Frankish colonisation.
The move was aimed at offsetting and undermining the authority of the duke of Gascony Lupo II after the setback suffered by the Franks at the Battle of Roncevaux in 778 and failure to restrain the Basques.
That advance clearly displeased the Basques, with these policies sparking a stir on the banks of the Garonne (Count of Toulouse Chorso defeated by Odalric "Wasco").
The new appointment and his fresh military arrangements were met with the hostility of important local officials, who staged a rebellion, burning alive supporters of the new count.
However, in 864 we hear of Arnold, Sancho Sanchez's nephew and a native from the area, holding the title of count of Fezensac.
Note : In 1777, the Montesquiou family was recognized as descending from the first counts of Fezensac and Louis XVI allowed them to change their name to "de Montesquiou-Fezensac".