Kingdom of Sardinia and Aosta, dynastic possessions since the 11th century, the Principality of Piedmont (a possession built up in the 13th century), and the County of Nice (a possession since 1388). While in theory the traditional capital of the island of Sardinia and seat of its viceroys was Cagliari, the Piedmontese city of Turin was the "de facto" capital of Savoy. When the mainland domains of the House of Savoy were occupied and eventually annexed by Napoleonic France, the king of Sardinia made his permanent residence on the island for the first time in its history. The Congress of Vienna (1814–15), which
Sardinia occupied the territory. The Giudicato of Arborea, having Oristano as its capital, had the longest life compared to the other kingdoms. Its later history is entwined with the attempt to unify the island into a single Sardinian state ("Republica sardisca" "Sardinian Republic" in Sardinian, "Nació sarda" or "sardesca" "Sardinian Nation" in Catalan) against their relatives and former Aragonese allies. In 1297, Pope Boniface VIII established on his own initiative ("motu proprio") a hypothetical "regnum Sardiniae et Corsicae" ("Kingdom of Sardinia and Corsica") in order to settle the War of the Sicilian Vespers diplomatically. This had broken out in 1282 between