In October 1797, Frederica of Baden married King Gustav IV Adolf of Sweden. The marriage had been arranged by Gustav IV Adolf himself, after he had refused to marry first Duchess Louise Charlotte of Mecklenburg-Schwerin, since his desired marriage to Ebba Modée had been refused him, and second the Russian Grand Duchess Alexandra Pavlovna, because her proposed marriage contract would have allowed Alexandra to keep her Orthodox faith. Frederica of Baden was seen as a suitable choice: Russia could not officially disapprove a new bride after the Russian Grand Duchess had been refused if the bride was the sister-in-law of Grand Duke Alexander, which indirectly preserved an alliance between Sweden and Russia, and additionally, Gustaf IV Adolf wanted a beautiful spouse and expected her to be so after having had a good impression of her sister during his visit to Russia the year prior. The king visited Erfurt to see her and her family himself in August 1797, the engagement was declared immediately after, and the first marriage ceremony conducted in October.