Background
Caroline was born at Biebrich, Nassau-Usingen the second child and first daughter of Karl Wilhelm, Prince of Nassau-Usingen (1735–1803), and his wife, Countess Caroline Felizitas of Leiningen-Dagsburg (1734–1810), daughter of Christian Karl Reinhard, Count of Leiningen-Dagsburg-Heidesheim. Caroline, via her mother"s roots among the Alsace lords of Leiningen, was a cousin of the Danish aristocrat, the Duke of Augustenborg, they both being direct descendants of the important Danish and Sleswicker magnate and statesman Frederik Ahlefeldt, 1st HRR Reichsgraf zu Rixingen, 1st Lensgreve of Langeland (d 1686).