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. She was charged with conspiracy to conceal the crimes Marie Antoinette had been convicted of and of neglecting to report these crimes. She was called before the court on 25 July and judged guilty as charged. In accordance with the Law of 22 Prairial, she was sentenced to execution by guillotine the following day. According to a co-prisoner, who had not been sentenced to death, she behaved with courage during her trial.