The
Duchy of Nassau (
German:
Herzogtum Nassau), or simply
Nassau, was an independent state between 1806 and 1866, located in what is now the German states of
Rhineland-Palatinate and
Hesse. It was a
member of the
Confederation of the Rhine and later of the
German Confederation. Its ruling dynasty, now extinct, was the
House of Nassau. The duchy was named for its historical core city,
Nassau, although Nassau was not its capital. As of 1865, it had 465,636 inhabitants. After being occupied and annexed into the
Kingdom of Prussia in 1866, it was succeeded by the
Province of Hesse-Nassau. The area today is a geographical and historical region,
Nassau, and Nassau is also the name of the
Nassau Nature Park within the borders of the former duchy.