The Polesine's long Venetian era has a precise date: 7 August 1484. That day, at Bagnolo, the war between the Serenissima and the Duke of Ferrara, Ercole I d'Este, came to an end.
Among the causes of the conflict was salt: Venice objected to the illegal production of salt at Comacchio, as well as to border disputes in the Polesine of Rovigo and questions of duties and privileges. The first Venetian bastie (field forts) appeared in the Polesine as early as November 1481; in 1482 the Este fortress of Ficarolo fell.
The peace was harsh for Ferrara: Venice was allowed to keep the Polesine, which remained with the Republic until its fall. The traces are still there for all to see, starting with the lion of St Mark in the main square of Rovigo.
