The Duchy of Nassau was a historical territory in Germany, established in the early 19th century. It was part of the larger region known as Germany and was located in the central part of the country. The duchy was created in 1806 and became a significant political entity during the time of the German Confederation. The capital of the duchy was Wiesbaden, which served as an important administrative center. The Duchy of Nassau was known for its rich natural resources and economic development, particularly in mining and agriculture. It was eventually annexed by the Prussian Empire in 1866 during the Austro-Prussian War.