After that brief interlude, it passed by marriage of the last heiress, Margaret of Montferrat, to the House of Gonzaga, already dukes of Mantua. In 1574 the fief was elevated from Marquisat to Duchy.
Following a brief pause, the estate was transferred through marriage of the last heir, Margaret of Montferrat, to the House of Gonzaga, who were already Dukes of Mantua. In 1574, the fief was elevated from a Marquisate to a Duchy.