The Prince was a member of the Jacobin Club, and sat in the National Constituent Assembly after the French Revolution, constantly voting on the Liberal side. He served as chief of the staff to the First Republic's Army on the Rhine, but, during the Reign of Terror, he was denounced, arrested, and guillotined in Paris.
Since the old duc de Broglie survived him, the prince de Broglie's eldest son, Victor, eventually became the third duc de Broglie. The prince's dying admonition to his little son was to remain faithful to the principles of the Revolution, however unjust and ungrateful it seemed then to be.