A keen and extreme Ultramontanist, born at Chambéry, of a noble French family; accompanied the king of Sardinia in his retreat while the French occupied Savoy in 1792; was ambassador at St. Petersburg from 1803 to 1817, when he was recalled to the home government at Turin; wrote numerous works, the chief "Du Pape" and "Soirées de St. Petersbourg" (1753-1821).