By the influence of Colonel Duroc (afterwards duc de Frioul) he was attached to the personal staff of Napoleon.

He remained in the army at the Restoration, but, having accepted a command from Napoleon during the Hundred Days, he was retired until 1818, and took no further active part in affairs until the July Revolution of 1830.

The unfavourable portrait of Napoleon given in this book provoked representations from General Gourgaud, and eventually a duel, in which Ségur was wounded.

(2 vols., 1834–1842), in continuation of the history of France begun by his father; and the posthumous Histoire et mémoires (8 vols., 1873).

[1] His daughter, Marie Célestine Amélie d'Armaillé (1830–1918), was also a writer, biographer, and historian.