Original: In 1546 part of the island was handed over to Cosimo I de 'Medici, who fortified Portoferraio and renamed it "Cosmopoli", while in 1577 the rest of the island was returned to the Appiani.
Simplified: He fortified Portoferraio and renamed it "Cosmopoli". In 1577, the rest of the island was returned to the Appiani.