It was his intention first to take this city and then attack Forli, in the castle of which the mistress of the two cities, Catarina Sforza, had established herself for the purpose of resisting him.
While he was engaged in his campaigns in Romagna, his father was endeavoring to seize the hereditary possessions of the Roman barons.

He first attacked the Gaetani.

From the end of the thirteenth century this ancient family had held large landed estates in the Campagna and Maritima.

It had divided into several branches, one of which was settled in the vicinity of Naples.

There the Gaetani were Dukes of Traetto, Counts of Fundi and Caserta, and likewise vassals and favorites of the crown of Naples.
Sermoneta, the center of the domain of the Gaetani family in the Roman Campagna, was an ancient city with a feudal castle, situated in the foothills of the Volscian mountains.