In the 1323 the city was offered to the king of Aragon

The Ghibelline party quite soon, stroke up a friendship with Giacomo II king of Aragon (who was vested with the title of king of Sardinia from Pope Bonifacio VIII in 1297), succeeding to raise the population against the podestà sent from Genoa. In 1323, the city was offered to the king of Aragon. Nearly at the same time, the troops of Sassari marched to the flank of the Aragoneses, against Cagliari and Villa di Chiesa (Iglesias). However, the limitations imposed by the Infante Alfonso d’Aragona (that had modified the communal Statutes) let develop the population's dissatisfaction, ending up in the murder of the city governor.

After a period of tensions, the calm was restored in Sassari, but the Infante Alfonso order a walls' construction around the inhabited center: more than a mile-and-a-half long. These walls would have been useful for facing toward the assault of the armies of the Giudicato d’Arborea and of the Genovese family of the Doria, that had already dominated the territories of Bosa and Alghero.

The reinforces from Barcelona had to intervene in more than one occasion. In 1353, the king Pietro IV ( known also as “Il Cerimonioso”) in person won the battle of Porto Conte and took control of Alghero. In 1369, under the umpteenth attack of the Giudicato d’Arborea, Sassari fell, but it was reconquered by the Aragoneses, two years later. The assaults came one after the other with the passage of years, weakening the population and the soldiers