Documenti inediti sui rapporti tra Pisa e la Sardegna nel Fondo Comune, Divisione A, dell'Archivio di Stato di Pisa

This work focuses on the relations between Sardinia and Pisa between 1297 and 1345 as a result of the systematic examination of the collection “Comune, Divisione A” housed in the Pisa State Archive, which led to the identification of 345 significant documents for the purpose of this research. It was thus possible to retrace the history of Sardinia using new data starting exactly from 1297, when Boniface VIII, in compliance with the Treaty of Anagni signed on June 24th 1295, established the Regnum Sardiniae et Corsicae, in order to solve the political and diplomatic crisis between the Crown of Aragon and the Duchy of Anjou after the War of the Vespers to gain control over Sicily. As the threat of the Aragonese conquest became greater, the Pisans strengthened the defensive system of the city of Cagliari by building towers and walls around it. During the 26 years between the Pope's investiture and the beginning of the military campaign to conquer Sardinia, James II engaged in intense diplomatic activities aimed at isolating Pisa in the international scene, finding a crucial ally in Hugh II Giudice (Judge) of Arborea to carry out the conquest of the island, which started in 1323 with the siege of Villa di Chiesa followed by the one of Castel di Castro. In 1326 the final peace treaty was signed between James II, King of Aragon, and Pisa at the end of the military operations carried out in Sardinia, unfavourable to the Pisan side. The Sardinian dominions, which Pisa had conquered with difficulty and strenuously defended, were lost forever.