She was somewhat of a contrast to the seductiveness of the queen's favorite, but had a solid character and lacked far-reaching ambitions.
On 21 June, she was alerted about the Flight to Varennes by the queen, and left Paris for her estate in the countryside.
d'Ossun lost her position through the abolition of the monarchy, and thereby the royal court and household, following the storming of the Tuileries Palace by armed revolutionaries in the Insurrection of 10 August 1792, and returned to private life.
During the Reign of Terror, d'Ossun was arrested and imprisoned at the Maison des Oiseaux.
The protocol stated: "Age 44, born and resident of Paris, the widow d'Osson, a former noblewoman and Marechale, previously the lady-in-waiting of the widow Capet, was sentenced to death on the 8 Thermidor the Year II in Paris by the Revolutionary Court as conspirator.