 Born in Ferrara, the son of Alberto d'Este and Isotta Albaresani, he inherited the rule of the city in 1393 when only 10 years old.As a minor he was guided by a Regency Council supported by the Republics of Venice, Florence and Bologna.In 1395 the troops of the Regency Council were attacked at the Battle of Portomaggiore by Niccolò's relative Azzo X d'Este, a descendant of Obizzo II d'Este, who contested Niccolò's right to rule in Ferrara due to his illegitimate birth, even though Niccolò had been legitimated by his father.