For ten centuries, the Château de Chastellux has been continuously expanded, embellished, and restored by successive generations who have always remained its owners. The de Chastellux family traces its origins to the de Montréal family, a powerful Burgundian house close to the Duke of Burgundy, whose fief was located on the border between Burgundy and Champagne.
Guy, the younger brother of Anséric IV de Montréal, broke away from the fief of Montréal in the early 13th century and established his own line in the seigneury of Beauvoir. The lords of Beauvoir came to own significant fiefs, such as the seigneuries of Chastellux and Bazoches, and the viscountcy of Avallon. In the early 14th century, they settled in Chastellux and made it their primary residence, never changing it since. The family then adopted “Chastellux”—the fief of their residence—as their surname, abandoning the name “Beauvoir.”
The independence of the seigneury of Chastellux came to an end in 1321 with the oath of allegiance sworn to the Duke of Burgundy and the recognition of ducal suzerainty. The lords of Chastellux would henceforth always stand by the Duke of Burgundy, particularly during the Hundred Years’ War.
At the end of the 15th century, when the Duchy of Burgundy ceased to exist, the Chastellux family pledged allegiance to the King of France.