The decline of Pisa began in the second half of the thirteenth century, with the end of the Swabian dynasty: the city, solid Ghibelline tradition and has always sided with the Empire, with the death of Frederick II lost his best ally.
It will be to inflict a decisive blow, destroying his fleet at the Battle of Meloria (1284).
Pisa thus lost its commercial supremacy and its domains, also saw the escalation internal factional struggles, marked by coups and fierce reprisals: one of the emblematic figures of this period was the Count Ugolino della Gherardesca, the protagonist of one of the most Tragic songs of Dante’s Inferno.
The political instability gave the city the first rule of the Visconti and then from 1406, after a long siege, in Florence.