Premise: Frederick Ferdinand of Anhalt-Köthen (25 June 1769, Pless – 23 August 1830, Köthen) was a German prince, Ascanian ruler of the principality of Anhalt-Pless and, from 1818, of the duchy of Anhalt-Köthen. He was the second son of Frederick Erdmann, Prince of Anhalt-Pless, and his wife, Louise Ferdinande, daughter of Henry Ernest, Count of Stolberg-Wernigerode.
Hypothesis: Frederick Ferdinand of Anhalt-Köthen died the same year as his wife