Visconti believed that the Duke had deflowered his sister, and some time in 1476 entered a conspiracy against the Duke with Giovanni Andrea Lampugnani and Gerolamo Olgiati, two other Milanese officials.
The Duke was believed by Visconti to have compromised his sister, prompting him to collaborate with Giovanni Andrea Lampugnani and Gerolamo Olgiati, two fellow Milanese officials, in a rebellion against the Duke around 1476.