he Habsburgs, since Ercole's daughter Maria Beatrice Ricciarda d'Este was married to a cadet Habsburg, Archduke Ferdinand of Austria-Este. Ercole died in 1803 and Breisgau passed to his daughter and her husband, who then (1806) lost it during the Napoleonic reorganization of the western territories of the defunct Holy Roman Empire to the enlarged and elevated Grand Duchy of Baden.

ghter of grand-duke Cosimo I of Tuscany, then after becoming a widower, Barbara, the sister of Maximilian II, Holy Roman Emperor (1527–1576) and finally a third wife, Margherita Gonzaga, daughter of the duke of Mantua.
Though he raised the glory of Ferrara to its highest point, and was the patron of Torquato Tasso and Giovanni Battista Guarini, favouring the arts and sciences, as the princes of his house had always done, the legitimate line ended in 1597 with him. Emperor Rudolph II recognized as heir his first cousin Cesare d'Este (1533–1628), member of a cadet branch born out of wedlock, who continued to rule in the imperial duchies and carried on the family name. Ferrara, on the other hand, was annexed by force of arms in 1598 by Pope Clement VIII, on grounds of the heir's illegitimacy, and incorporated into the Papal States.
The last duke, Ercole III, was deposed in 1796 by the French and his two duchies became the Cispadane Republic which one year later was merged into the Cisalpine Republic and then into the Napoleonic Kingdom of Italy. Ercole was compensated in 1801 with the small principality of Breisgau in southwestern Germany, whose previous rulers, the Habsburgs, ceded it to him in anticipation of its eventual return to the Habsburgs, since Ercole's daughter Maria Beatrice Ricciarda d'Este was married to a cadet Habsburg, Archduke Ferdinand of Austria-Este. Ercole died in 1803 and Breisgau passed to his daughter and her husband, who then (1806) lost it during the Napoleonic reorganization of the western territories of the defunct Holy Roman Empire to the enlarged and elevated Grand Duchy of Baden.

Castello Estense in Ferrara



Ducal Palace in Modena, built in 1634 by Francesco I. d’Este

Austria-Este and the House of Habsburg[edit]

Main article: Austria-Este
In 1814, when French rule in Italy ended (but after the death of Duke Ercole), Modena was returned to his daughter Mary Beatrice and her son, Archduke Francis of Austria-Este. The family thus ruled the duchy of Modena and Reggio again from 1814 to 1859, using the names Asburgo-Este (Habsburg-Este) and Austria-Este. In 1859 the duchy lost its independence to the new united Italy, and Francis V, Duke of Modena, was deposed.