The Duchy of Brunswick (German: Herzogtum Braunschweig) was a historical state in Germany. Its capital was the city of Brunswick (Braunschweig).It was established as the successor state of the Principality of Brunswick-Wolfenbüttel by the Congress of Vienna in 1815. In the course of the 19th-century history of Germany, the duchy was part of the German Confederation, the North German Confederation and from 1871 the German Empire.