The title "Duke of Schleswig" refers to a historical noble title associated with the region of Schleswig, located in present-day Denmark and Germany. The title emerged in the Middle Ages and was held by various rulers, often linked to the larger Duchy of Schleswig and the Duchy of Holstein. The dukes played significant roles in the political landscape of Northern Europe. The title became particularly notable during the 19th century, especially in the context of the Schleswig Wars, which were conflicts over the control of the duchies. The disputes involved various powers, including Prussia and Austria, leading to significant changes in the region's governance and territorial boundaries.