On the Iberian peninsula the muslim state of Cordoba was under attack. By 1100 a number of small states were founded; Catalonia, Aragon, Leon and Castilia. In time Catalonia merged with Aragon under the Crown of Aragon, like Leon merged with Castilia. It would give Aragon the control over Barcelona and with that access to the western Meditteranean where it soon became an important maritime power. Aragon extended its territory to the south to Valencia, then east to the Balearic Islands. It would only be a matter of time before the king of Aragon would take interest in Sardinia and Sicily, and he was thereby aided by the Pope in Rome 1.
The Crown of Aragon, the Pope and the Judicate of Arborea
Pope Boniface VIII, convinced he could dispose of the islands as he wished, gave Sardinia and Corsica to the king of Aragon in 1297. But it would take until 1325 before the king could effectively establish his dominion over Sardinia. He obtained help from Marian III and later from Hugo II of Arborea who wanted to use this alliance to throw out the Pisans to become themselves the only masters of the island as vasals of the king. In 1323 Hugo II signed an agreement to that effect with the king of Aragon. The Pisans were defeated, leaving them only control over Cagliari, while the Genovese submitted themselves as vasal of the king to hold on to their posessions 2.
When Aragon gained control over large parts of Sardinia the son of Hugo II, Marian IV, decided to take up arms against the Aragonese in 1353. The reason was the attack by the Aragonese on Porto Conte in the north of Sardinia, then in hands of the Genovese Doria family. Marian IV succeeded in gaining control of large parts of Sardinia. By marrying his daughter Eleonora to Brancaleone Doria he forged a political bond with the Doria family, and by marrying his daughter Beatrix to the Viscount of Narbona with Narbona in France. The king of Aragon could not react because occupied at that time with Castilia 3.
In 1376 Marian IV died of the plague and his weaker son Hugo III followed him up. A year later Frederic of Sicily died. The king of Aragon saw his chance and decided to arm a large fleet to submit Sicily and Sardinia to his lordship and tried to isolate the Judicate of Arborea through negotiations with Genua and the Pope. The fleet would never sail because of financial problems, the same problems that would weaken his hold of Cagliari. Hugo III would have tried to oust the Aragonese from Sardinia but the impopular Iudex was mudered in 1383 during a riot 4.
The news quickly reached the king of Aragon, the Viscount of Narbona and Brancaleone Doria. The last two hastly traveled to the court of Aragon to forward their rights to Arborea. In the meantime Eleonora, who had stayed for some time at Genua, took the initiative in her own hands. She traveled straight to Oristano and thanks to her popularity she obteined the support of the parliament (the Corona de Logu) and was chosen as Giudicessa. Brancaleone, her husband, was detained by the king of Aragon and negotiations followed. When Brancaleone was released in 1390 and returned to Sardinia open war broke out. In 1402 (or 1404) Eleonora d'Arborea died. The new Iudex, William III son of Beatrix, lost the war against Aragon a few years later. The Aragonese had armed another fleet in 1408 that set sail from Sicily and in 1409 the Judicate of Arborea lost the decisive battle at San Luri. The Judicate of Arborea ceased to exist and a new Marquess of Oristano was appointed by the king of Aragon 5.
1. Backman, C.R. 2015, The worlds of medieval Europe, New York
2. Ferrer i Mallol, M.T. 2000, La guerra d'Arborea alla fine del XIV secolo in: Giudicato d'Arborea e Marchesato di Oristano: proiezioni mediterranee e aspetti di storia locale, ed. G. Mele, Oristano, p. 535-620
3. Galoppini, L. 2004, La Sardegna giudicale e catalano-aragonese in: Storia della Sardegna, ed. M. Brigaglia, Cagliari, p. 131-168