The Kingdom of Sardinia was a feudal state in Southern Europe created in the early 14th century and a possession of the Crown of Aragon first and then of the Spanish Empire until 1708, then of the Habsburgs until 1717, and then of the Spanish Empire again until 1720.

The kingdom was a part of the Crown of Aragon and initially consisted of the islands of Sardinia and a claim to the island of Corsica, sovereignty over both of which was claimed by the papacy, which granted them as a fief, the (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.

In 1720, the island was ceded by the Habsburg and Bourbon claimants to the Spanish throne to the Duke of Savoy, Victor Amadeus II of Savoy. Sardinia retained its autonomous institutions according to the treaty of cession until 1847, when King Charles Albert enacted the Perfect Fusion, which expanded to the island the centralized administrative system which was adopted by the mainland Savoyard state during the Napoleonic era.

Early history

In 238 BC, Sardinia became, along with Corsica, a joint province of the Roman Republic. The Romans ruled the island until the middle of the 5th century when it was occupied by the Vandals, who had also settled in north Africa. In 534 AD it was reconquered by the Eastern Roman (Byzantine) Empire. It remained a Byzantine province until the Muslim conquest of Sicily in the 9th century. After that, communications with the Byzantine capital, Constantinople, became very difficult, and powerful families of the island assumed control of the land.

Starting from 705 to 706, Saracens from north Africa (recently conquered by Arab armies) harassed the population of the coastal cities. Facing Arab attempts to sack and conquer the island, while having almost no outside help, Sardinia used the principle of translatio imperii ("transfer of rule") and continued to organize itself along the ancient Roman and Byzantine model. The island was not the personal property of the ruler and of his family, as was then the dominant practice in western Europe, but rather a separate entity and during the Byzantine rule, a monarchical republic, as it had been since Roman times.

Information about the Sardinian political situation in the following centuries is scarce. Due to Saracen attacks, in the 9th century Tharros was abandoned in favor of Oristano, after more than 1800 years of occupation; Caralis, Porto Torres, and numerous other coastal centres suffered the same fate. There is a record of another massive Saracen sea attack in 1015–16 from the Balearics, commanded by Mujāhid al-ʿĀmirī (Latinized as Museto). The Saracen attempt to invade the island was stopped by the Judicates with the support of the fleets of the maritime republics of Pisa and Genoa. Pope Benedict VIII also requested aid from the two maritime republics in the struggle against the Arabs.B. MARAGONIS, Annales pisani a.1004–1175, ed. K. PERTZ, in MGH, Scriptores, 19, Hannoverae, 1861/1963, pp. 236–2 and Gli Annales Pisani di Bernardo Maragone, a cura di M. L.GENTILE, in Rerum Italicarum Scriptores, n.e., VI/2, Bologna 1930, pp. 4–7. "1017. Fuit Mugietus reversus in Sardineam, et cepit civitatem edificare ibi atque homines Sardos vivos in cruce murare. Et tunc Pisani et Ianuenses illuc venere, et ille propter pavorem eorum fugit in Africam. Pisani vero et Ianuenses reversi sunt Turrim, in quo insurrexerunt Ianuenses in Pisanos, et Pisani vicerunt illos et eiecerunt eos de Sardinea."

After the East–West Schism, Rome made many efforts to restore Latinity to the Sardinian church, politics and society, and to finally reunify the island under one Catholic ruler, as it had been for all of southern Italy, when the Byzantines had been driven away by Catholic Normans. Even the title of "Judge" was a Byzantine reminder of the Greek church and state, in times of harsh relations between eastern and western churches (Massacre of the Latins, 1182, Siege of Constantinople (1204), Recapture of Constantinople, 1261).

Before the Kingdom of Sardinia and Corsica, the archons (), or in Latin,C. Zedda-R. Pinna, La nascita dei giudicati, proposta per lo scioglimento di un enigma storiografico, su Archivio Storico Giuridico Sardo di Sassari, vol. n°12, 2007, Dipartimento di Scienze Giuridiche dell'Università di SassariF. Pinna, Le testimonianze archeologiche relative ai rapporti tra gli Arabi e la Sardegna nel medioevo, in Rivista dell'Istituto di storia dell'Europa mediterranea, Consiglio Nazionale delle Ricerche, n°4, 2010 who reigned in the island from the 9th or 10th century until the beginning of the 11th century, can be considered real kings of all Sardinia (),Archeological museum of Cagliari, from Santa Sofia church in VillasorGeorg Heinrich (ed.), MGH, Scriptores, Hannoverae, 1863, XVIII, pp. 56–96."Antiquitas nostra primum Calarense iudicatum, quod tunc erat caput tocius Sardinie, armis subiugavit, et regem Sardinie Musaitum nomine civitati Ianue captum adduxerunt, quem per episcopum qui tunc Ianue erat, aule sacri palatii in Alamanniam mandaverunt, intimantes regnum illius nuper esse additum ditioni Romani imperii." –Oberti Cancellarii, Annales p. 71.Crónica del califa 'Abd ar-Rahmân III an-Nâsir entre los años 912–942,(al-Muqtabis V), édicion. a cura de P. CHALMETA – F. CORRIENTE, Madrid, 1979, p. 365 "Tuesday, August 24th 942 (A.D.), a messenger of the Lord of the island of Sardinia appeared at the gate of al-Nasir ... asking for a treaty of peace and friendship. With him were the merchants, people Malfat, known in al-Andalus as from Amalfi, with the whole range of their precious goods, ingots of pure silver, brocades etc. ... transactions which drew gain and great benefits" even though nominal vassals of the Byzantine emperors. Of these sovereigns, only two names are known: Turcoturiu and Salusiu (Constantini Porphyrogeneti De caerimoniis aulae Byzantinae, in Patrologia cursus completus. Series Graeca CXII, Paris 1857 (),Roberto Coroneo, Scultura mediobizantina in Sardegna, Nuoro, Poliedro, 2000Roberto Coroneo, Arte in Sardegna dal IV alla metà dell'XI secolo, edizioni AV, Cagliari 2011 who probably ruled in the 10th century. The archons still wrote in Greek or Latin, but one of the oldest documents left of the Judicate of Cagliari (the Carta Volgare), issued by Torchitorio I de Lacon-Gunale in 1070, was already written in the Romance Sardinian language, albeit with the Greek alphabet.Ferrer, Eduardo Blasco (1984). Storia Linguistica Della Sardegna, p. 65, De Gruyter

The realm was divided into four small kingdoms, the Judicates of Cagliari, Arborea, Gallura and Logudoro, perfectly organized as was the previous realm, but was now under the influence of the papacy, which claimed sovereignty over the entire island, and in particular of the Italian states of Genoa and Pisa, that through alliances with the "judges" (the local rulers), secured their political and economic zones of influence. While Genoa was mostly, but not always, in the north and west regions of Sardinia, that is, in the Judicates of Gallura and Logudoro; Pisa was mostly, but not always, in the south and east, in the Judicates of Cagliari and Arborea. That was the cause of conflicts leading to a long war between the Judges, who regarded themselves as kings fighting against rebellious nobles.

Later, the title of King of Sardinia was granted by the Emperor of the Holy Roman Empire to Barisone II of Arborea,G. Seche, "L'incoronazione di Barisone 'Re di Sardegna' in due fonti contemporanee: gli Annales genovesi e gli Annales pisani", in Rivista dell'Istituto di storia dell'Europa mediterranea, Consiglio Nazionale delle Ricerche, no. 4, 2010. and subsequently also to Enzio of Sardinia. The first could not reunify the island under his rule, despite years of war against the other Sardinian judges, and he finally concluded a peace treaty with them in 1172.Dino Punchu (ed.), "I Libri Iurium della Repubblica de Genova", Ministero per i Beni Culturali e Ambientali, Rome, 1996, no. 390, p. 334. The second did not have the opportunity. Invested with the title from his father, Emperor Frederick II in 1239, he was soon recalled by his parent and appointed Imperial Vicar for Italy. He died in 1272 without direct recognized heirs after a detention of 23 years in a prison in Bologna.

The Kingdom of Sardinia and Corsica, later only the Kingdom of Sardinia from 1460,Geronimo Zurita, Los cinco libros postreros de la segunda parte de los Anales de la Corona d'Aragon, Oficino de Domingo de Portonaris y Ursono, Zaragoza, 1629, libro XVII, pp. 75–76. was a state whose king was the King of Aragon, who started to conquer it in 1324, gained full control in 1410, and directly ruled it until 1460. In that year it was incorporated into a sort of confederation of states, each with its own institutions, called the Crown of Aragon, and united only in the person of the king. The Crown of Aragon was made by a council of representatives of the various states and grew in importance for the main purpose of separating the legacy of Ferdinand II of Aragon from that of Isabella I of Castile when they married in 1469.

The idea of the kingdom was created in 1297 by Pope Boniface VIII, as a hypothetical entity created for James II of Aragon under a secret clause in the Treaty of Anagni. This was an inducement to join in the effort to restore Sicily, then under the rule of James's brother Frederick III of Sicily, to the Angevin dynasty over the oppositions of the Sicilians. The two islands proposed for this new kingdom were occupied by other states and fiefs at the time. In Sardinia, three of the four states that had succeeded Byzantine imperial rule in the 9th century had passed through marriage and partition under the direct or indirect control of Pisa and Genoa in the 40 years preceding the Treaty of Anagni. Genoa had also ruled Corsica since conquering the island nearly two centuries before (c. 1133).

There were other reasons beside this papal decision: it was the final successful result of the long fight against the Ghibelline (pro-imperial) city of Pisa and the Holy Roman Empire itself. Furthermore, Sardinia was then under the control of the very Catholic kings of Aragon, and the last result of rapprochement of the island to Rome. The Sardinian church had never been under the control of the Ecumenical Patriarchate of Constantinople; it was an autonomous province loyal to Rome and belonging to the Latin Church, but during the Byzantine period became influenced by Byzantine liturgy and culture.

Foundation of the Kingdom of Sardinia

In 1297, Pope Boniface VIII, intervening between the Houses of Anjou and Aragon, established on paper a Regnum Sardiniae et Corsicae that would be a fief of the papacy. Then, ignoring the indigenous states which already existed, the pope offered his newly invented fief to James II of Aragon, promising him papal support should he wish to conquer Pisan Sardinia in exchange for Sicily. In 1323 James II formed an alliance with Hugh II of Arborea and, following a military campaign which lasted a year or so, occupied the Pisan territories of Cagliari and Gallura along with the city of Sassari, claiming the territory as the Kingdom of Sardinia and Corsica.