 From 10 April 1766 to 24 December 1770, he served as Secretary of State for the Navy (his cousin Étienne then taking back the department of Foreign Affairs in addition to that of War).During his term in office, he restorated the strength of the Navy, which had been severely damaged during the Seven Years' War.After the death, in 1764, of Madame de Pompadour, who had been their protector, the position of César Gabriel and his cousin Étienne was undermined.