After the French Revolution Lacépède became a member of the Legislative Assembly, but during the Reign of Terror he left Paris, his life having become endangered by his disapproval of the massacres. When the Jardin du Roi was reorganised as the Jardin des Plantes and as the Muséum National d'Histoire Naturelle in 1793, Lacépède was appointed to the chair allocated to the study of reptiles and fishes. In 1798, he published the first volume of "Histoire naturelle des poissons", the fifth volume appearing in 1803, and in 1804 appeared his "Histoire des cétacées". From this period until his death the part he took in politics prevented him making any further contribution of importance to science. In 1799, he became a senator, in 1801 president of the senate (a role he also fulfilled in 1807–08 and 1811–13), in 1803 grand chancellor of the Legion of Honor, in 1804 minister of state, and at the Bourbon Restoration in 1819 he was created a peer of France.