The Kingdom was a member of the Council of Aragon and initially consisted of the islands of Corsica and Sardinia, sovereignty over both of which was claimed by the Papacy, which granted them as a fief, the "regnum Sardiniae et Corsicae" ("kingdom of Sardinia and Corsica"), to King James II of Aragon in 1297. Beginning in 1324, James and his successors conquered the island of Sardinia and established "de facto" their "de jure" authority. In 1420, after the Sardinian–Aragonese war, the last competing claim to the island was bought out. After the union of the crowns of Aragon and Castile, Sardinia became a part of the burgeoning Spanish Empire.