The Duke of Brunswick is a title associated with the historical region of Brunswick in Germany. The title has been held by various noble families, primarily the House of Welf. The Dukes played significant roles in the political landscape of Germany, particularly during the Middle Ages and the early modern period. The most notable Duke of Brunswick was Charles I, who ruled in the 19th century and was known for his military leadership. The title has since become largely ceremonial, with the last reigning duke, Ernest Augustus, abdicating in 1918 following the end of the German monarchy.