Frederika of Oldenburg Germanic duchess 1820-1891 (1820–1891) Parents Princess Adelheid of Anhalt-Bernburg-Schaumburg-Hoym Augustus, Grand Duke of Oldenburg Children Stephan Ludwig Freiherr von Washington George von Washington Siblings Duke Nikolaus of Oldenburg Duke Elimar of Oldenburg Amalia of Oldenburg Duke Alexander of Oldenburg Peter II, Grand Duke of Oldenburg Partners Maximilian Emanuel von Washington