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I bought this letter for a few euros for the stamps, a Y&T n° 50 (1 c Cérès) and a Y&T n° 60 (25 c Cérès) on ebay some time ago.
I became curious about it's history.
This letter was posted in 1873 and addressed to the "Marquise de Saint-Exupéry", residing in Agen, France.
When it arrived there on July 27, the family was clearly residing at their summer address, the Arasse castle.
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The Agen address was barred and the "Chateau d'Arras" was added.
Unfortunately I have not found any picture of this castle. If someone finds it, let me know. I did find that it is located near Foulayronnes, more specifically near the place known as "La Croix Blanche" (The White Cross) located in the department of Lot-et-Garonne and the Aquitaine region.
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The castle goes back to 1510 at least, when it was owned by the Godailh family. It fell to the Lauriere family through heritage in 1755. Finally, it became a possession of Balthazar Joseph, the Marquis de Saint-Exupéry as he married into the Lauriere family. That is the very lady to whom this letter was addressed: Josephine Louise Delly Montesquieu. She was a "Lauriere" from her mother's side and a "Montesquieu" from father's side. Through her marriage she became the Marquise de Saint-Exupéry.
The letter congratulates the Marquise de Saint-Exupéry on the occasion of the intended marriage of her daughter Thérèse, with a young captain referred to as "de Lusignan".
It is Thérèse's aunt that wrote.
She hopes the young couple will visit her in Nice after the wedding; surely they will make a trip along the mediteranian coast and perhaps to Italy after their wedding!
Thérèse de Saint-Exupéry in fact did marry Adhemar de Lusignan, as one can see on a family tree to be found on
http://www.lot-et-garonne.fr/html/archives_nouveau_Site/recherche/Bora/083J.pdf