Leonello d'Este was Marquis of Ferrara, Modena, and Reggio Emilia from 1441 to 1450. Despite the presence of legitimate children, Leonello was favoured by his father as his successor. In addition, his virtuous qualities, high level of education, and popularity among the common people as well as his formal papal recognition ultimately made him the most suitable heir.
Leonello had little influence over the Italian political landscape and aristocracy in Ferrara. Contrary to other prior d’Este family leaders, such as Azzo VII, Niccolò III, and Isabella d’Este, who had a drive for power and control, Leonello is recognized principally for his sponsorship of the arts, literature, and culture. In 1441–1450, his learned courts and developing knowledge assisted him in transforming the city of Ferrara. Under the guidance of Guarino Veronese, his humanist teacher, and with the approval of the commune, Leonello began the reformation, particularly, the University of Ferrara.
Leonello not only elevated the humanistic cultural movements during his rule, but it also influenced the political and artistic advancements of his successors.