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He grew up at the court of Ferrara. After his father's death, the title passed to his brother Alfonso I d'Este.
In contrast to Ferrante d'Este and Giulio d'Este, Sigismund never attempted to oppose the brothers Alfonso and Ippolito d'Este, but rather lived in their shadow. Sigismund often accompanied the Duke on his travels in and out of the duchy.
When the conspiracy organized by Ferrante and Giulio was discovered, the trial against the two and other conspirators took place in the palace of Sigismund.
Alfonso and Ferrante contracted syphilis between 1496 and 1497, but while the brothers were able to recover Sigismund was unable to lead a normal life.