Article XVII provided for a mutual exchange of all prisoners of war. According to article XV, allied troops were to leave the Danish Duchy of Schleswig (Slesvig), but were allowed to remain in the German confederal Duchy of Holstein (Holsten), ruled in personal union with Denmark and Schleswig, to participate in the encirclement of Hamburg. In article XXVII, former Dano-Swedish peaces were confirmed as long as their provisions were not in conflict with the treaty of Kiel, namely the Treaty of Copenhagen (1660), the Treaty of Stockholm (June 1720), the Treaty of Frederiksborg (July 1720) and the Treaty of Jönköping (1809). A separate article was concerned with the cession of hostilities.