Freycinet's cabinet, he erased the name of the duc d'Aumale from the army list, as part of the republican campaign against the Orleanist and Bonapartist princes.
The execution of his father in November 1793 had made him duke of Orleans, and he now became the centre of the intrigues of the Orleanist party.
In 1866 he was employed at the ministry of war in the preparation of army reorganization schemes, and he published anonymously in the following year L'Armee francaise en 1867, a work inspired with Orleanist sentiment, which ran through ten editions in a few months and reached a twentieth in 1870.
Elected a member of the National Assembly in 1871, he zealously supported the Orleanist party.
His Orleanist tendencies and his objections to the republic were strong, and though he at first supported Tillers, he afterwards became a leader of the opposition to the president.