Map of Europe after the Congress of Vienna, 1815.
Although originally promised in marriage to the heir of Baden, Charles, the engagement was broken at the behest of Napoleon I of France. On 14 January 1806 in Munich, Augusta married Eugène de Beauharnais, only son of Josephine de Beauharnais and Alexandre, vicomte de Beauharnais and stepson of Napoleon. Although a diplomatic marriage, this union would turn out to be a happy one. In 1817, Augusta's father created his son-in-law Duke of Leuchtenberg and Prince of Eichstädt, with the style Royal Highness.
Augusta and Eugène had seven children:
- Princess Joséphine Maximiliane Eugénie Napoléonne de Beauharnais (1807–1876); married Oscar I of Sweden, himself the son of Napoleon's old love, Désirée Clary.
- Princess Eugénie Hortense Auguste de Beauharnais (1808–1847); married Friedrich, Prince of Hohenzollern-Hechingen.
- Prince Auguste Charles Eugène Napoléon de Beauharnais, 2nd Duke of Leuchtenberg (1810–1835); married Maria II of Portugal. There was no issue from this marriage.
- Princess Amélie Auguste Eugénie Napoléone de Beauharnais (31 July 1812 – 26 January 1873); married Pedro I of Brazil (father of Maria II of Portugal and Pedro II of Brazil) and became Empress of Brazil.
- Princess Theodelinde Louise Eugénie Auguste Napoléone de Beauharnais (1814–1857); married Wilhelm, 1st Duke of Urach.
- Princess Carolina Clotilde de Beauharnais (1816)
- Prince Maximilian Josèphe Eugène Auguste Napoléon de Beauharnais (1817–1852); married Grand Duchess Maria Nikolaievna of Russia, eldest daughter of Nicholas I of Russia, and received the title of "Prince Romanovsky" with the style "Imperial Highness", in 1852.