For 10 points, identify this issue regarding the contested ownership of two duchies on the German-Danish border.
One conflict over this issue included the Battle of Fredericia. The resolution of this issue was the basis for the National Liberal Party's Eider Program, and after the first war fought over this issue, a resolution was attempted with the London Protocol. Another conflict over this issue was ended by the 1864 Peace of Vienna, which was followed by two nations negotiating the dual-sovereignty Convention of (*) Gastein to postpone a resolution to this issue. This issue was partly resolved by the signing of the Treaty of Prague after one nation's defeat in the Seven Weeks' War, resulting in the assignment of the disputed territories to Prussia. For 10 points, identify this issue regarding the contested ownership of two duchies on the German-Danish border.
One conflict over this issue included the Battle of Fredericia.
the Schleswig-Holstein question