Kingdom of Sardinia
On 17 March 1861, law no. 4671 of the Sardinian Parliament proclaimed the Kingdom of Italy, so ratifying the annexations of all other Apennine states, plus Sicily, to the Kingdom of Sardinia. The institutions and laws of the Kingdom were quickly extended to all of Italy, abolishing the administrations of the other regions. Piedmont became the most dominant and wealthiest region in Italy and the capital of Piedmont, Turin, remained the Italian capital until 1865, when the capital was moved to Florence. But many revolts exploded throughout the peninsula, especially in southern Italy, and on the island of Sicily, because of the perceived unfair treatment of the south by the Piedmontese ruling class. The House of Savoy ruled Italy until 1946 when Italy was declared a republic by referendum. In this referendum the southern regions, including Sardinia, voted overwhelmingly in favor of the House of Savoy, with the results being 63.8% in favor of maintaining the monarchy.
Sardinia
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 the Capetian House of Anjou and Catalans over the possession of Sicily. Despite the existence of the indigenous states, the Pope offered this newly created crown to James II of Aragon, promising him support should he wish to conquer Pisan Sardinia in exchange for Sicily.
In 1324, in alliance with the Kingdom of Arborea and following a military campaign that lasted a year or so, the Aragon Crown Prince Alfonso led a Catalan army that occupied the Pisan territories of Cagliari and Gallura along with the allied city of Sassari, naming them ""The Kingdom of Sardinia and Corsica"". The kingdom was to remain a dominion of the Crown of Aragon (under the Kings of Spain) until the Treaty of Utrecht.