In 1763, the penultimate Este Duke of Modena, Francesco III, signed a treaty with the Empress Maria Theresa engaging the nine-year-old Ferdinand to his only son Ercole's daughter, Maria Beatrice, making him thus his heir. There had been an earlier treaty in 1753 making Ferdinand's older brother Peter Leopold the heir to the Duchy of Modena, but in 1761, Peter Leopold became heir to the Grand Duchy of Tuscany, which required a change to the Modena agreement.
In 1771, the Perpetual Imperial Diet approved the eventual investiture of Ferdinand with the imperial fiefs held by Ercole III.
Ferdinand became Governor of the Duchy of Milan on his marriage in 1771, as long as his father-in-law Ercole III d'Este still ruled the Duchy of Modena. He and his family lived in Milan.
In 1780, Ferdinand was confirmed as Governor of Lombardy by his brother, the new Holy Roman Emperor Joseph II. In 1796, Napoleon's invasion of Milan forced the family to flee the French forces. Duke Ercole III also had to flee Modena, which overthrew the monarchy and joined the Cisalpine Republic.
By the Treaty of Campo Formio in 1797, Duke Ercole III was granted the Duchy of Breisgau, a Habsburg territory in southwest Germany. When Ercole III died in 1803, Ferdinand succeeded as Duke of Breisgau, as well as "titular Duke" of Modena and Reggio. By the Treaty of Pressburg in 1805, Ferdinand ceded the Duchy of Breisgau to the Grand Duchy of Baden.
Ferdinand died the following year in Vienna, on 24 December. He is buried in the Imperial Crypt in Vienna.
In 1814, Ferdinand's eldest surviving son, Francis IV, was recognised as Duke of Modena by the Congress of Vienna.
Ancestry
Ancestors of Ferdinand Karl, Archduke of Austria-Este[1]
Weissensteiner, Friedrich. Die Söhne Maria Theresias. Wien: Kremayer & Scheriau, 1991.
Wurzbach, Constantin von. "Habsburg, Ferdinand Karl Anton von Este". In Biographisches Lexikon des Kaiserthums Oesterreich. 6. Theil. Kaiserlich-königliche Hof- und Staatsdruckerei, Wien 1860, S. 204 f.
Generations are numbered by male-line descent from the first archdukes. Later generations are included although Austrian titles of nobility were abolished in 1919.
Generations are numbered from the children of Francesco de' Medici, first Grand Duke of Tuscany. Later generations are included but the grand duchy was abolished in 1860.
