On 22 November 1754 in Coburg, she married Margrave Karl Alexander of Brandenburg-Ansbach and Bayreuth (1736-1806).

Although Frederica Caroline was considered virtuous, gentle, charitable and devout,[1] her husband found her ugly, ignorant and boring.

[2] The marriage remained childless, he separated from his wife, who by that time lived at Schwaningen Castle in Unterschwaningen, and began to live with his mistress Elizabeth Craven, Baroness Craven of Hamstead Marshall.

Frederica Caroline's brother, Prince Josias of Saxe-Coburg-Saalfeld, own his sister admission to the regiment as captain, this starting point of his brilliant military career.

After Frederica Caroline's death, her husband abdicated as Margrave and sold the Margravate to Prussia,[3] he left the country and married morganatically his English mistress that year, who became Princess Berkeley upon her marriage to Alexander.