PARIS NO ISABELLE

In France, during the 19th century, 15-year-old Isabelle Laustin, a noblewoman, officially enters the world of the aristocracy at a ball in Versailles. But shortly after, the French army is defeated at Sedan, and Isabelle and her family have to leave their mansion to take refuge in Paris, where they will take an active part in the fight against the Prussians. — Description from AniList community (anilist.co).