Born in Ferrara, the son of Alberto d’Este and Isotta Albaresani, he inherited the rule of the city when he was only 10 years old, under the protection of the Republics of Venice, Florence and Bologna. He was attacked by his relative Azzo X d’Este, a general of Gian Galeazzo Visconti, Duke of Milan, a descendant of Obizzo II d’Este who contested Niccolò the right to rule in Ferrara due to his illegitimate birth.1 Azzo was however taken prisoner by Astorre I Manfredi in the ensuing war, and any menace over Niccolò’s rule disappeared.
In 1397 he married Gigliola da Carrara, daughter of Francesco II da Carrara, lord of Padua.
Earlier this year he joined the league formed against the Duke of Milan, being appointed Captain General of the Papal Army by Pope Boniface IX.
He has one child, a son (illegitimate) Ugo, Age 7.