Rubuta ci gaba don wannan sakin layi - A scapegoat ga royalist wuce haddi na 1814, Blacas aka unofficially kore a matsayin Faransa jakadan zuwa kotu na Mulkin biyu Sicilies, wanda babban birnin kasar da aka located a Naples. A can, ya yi shawarwari game da auren 1816 na dan uwan Louis XVIII, Duke na Berry, zuwa Francis I na Sicilies 'yar Caroline. Hakanan a cikin 1816, Blacas ya zama memba na duka Académie des Inscriptions et Belles-Lettres da kuma Académie des Beaux-Arts. Bayan haka, an nada shi jakadan Faransa a wurin Holy See a Rome. Ya sanya hannu kan yarjejeniya tsakanin Bourbon Faransa da Paparoma Pius VII a ranar 11 ga Yuni 1817. A cikin 1820, ya karɓi "Ordre du Saint-Esprit". Duk da yake har yanzu jakadan a Roma, ya kasance daya daga cikin wakilan Faransa guda uku a Majalisa ta Laibach
a shekara ta 1821.