On 1 October 1450, Leonello suddenly died of unknown causes. Borso d'Este his brother, succeeded the throne of Marquis of Ferrara. In stark contrast to his brother, Borso received little education and was more interested in political affairs. During the reign of Borso, the legacy of art and literature proceeded with a rather stagnant growth as they were mostly used for military propaganda and entertainment. Aside from cultural developments, however, Borso utilized the foundation laid down by his brother, Leonello, to assist him in reforming the structure and organization of the state. In particular, the diplomatic relationship previously built up by Leonello served as a basis for Borso to further leverage its alliance with other cities. The impact of Leonello, however, was much greater and lasted much longer than the reign of Borso. The ties between the Kingdom of Naples and Ferrara carried on to the realm of Ercole who later become the Duke of Ferrara after Borso d’Este. Ercole married with Eleonora d’Aragona, Maria's niece, under the same contract Leonello signed in 1444 with Naples. Because of this, the strong alliance between the Este family and Naples kept Ferrara safe during the struggles between Milan and Venice in the 15th century.