Background
He is a son of Nikolaus, Hereditary Grand Duke of Oldenburg and Princess Helena of Waldeck and Pyrmont. Frederich August is the sixth child and fourth son of Nikolaus, Hereditary Grand Duke of Oldenburg and his first wife Princess Helena of Waldeck and Pyrmont. His grandfather was overthrown as Grand Duke of Oldenburg in 1918, at the end of World War I. His father Nikolaus thus never legally succeeded to the title when the deposed Grand Duke died in 1931.