German-Danish War (also Prusso-Danish War, Danish War), January 16 - October 30, 1864, over the duchies of Schleswig, Holstein and Lauenburg, up to then under the rule of the Danish king. The war was started by the Prussian prime minister O. von Bismarck, who skilfully managed to persuade the Austrian Emperor, Franz Joseph, and his foreign minister, J. B. Rechberg, to act independently of the Deutscher Bund and take part in a special mission against Denmark. Denmark, whose hopes of assistance from England proved illusory, soon had to surrender to the superiority of Prussia and Austria.
Under the Peace of Vienna, Denmark had to cede the duchies to the allies who, under the Convention of Gastein (August 14, 1865), agreed on their partition. In 1866 Prussian troops entered Holstein, which had been placed under Austrian rule, thus violating the Convention of Gastein. As a consequence, the Seven Week's War (1866, Austro-Prussian War broke out. After Austria's defeat, Franz Joseph had to acquiesce in Prussia's annexation of Schleswig-Holstein; Prussia's pledge to let the Danish population of northern Schleswig decide in a referendum whether they wanted to be part of Prussia or Denmark was never redeemed.
Literature#A. Kaernbach, Der preussisch-oesterreichische Dualismus im Lichte von Bismarcks Bemuehungen um eine Reform des Deutschen Bundes, doctoral thesis, Bonn 1988/1989; M. Klaus, Tegetthoffs Marsch in die Nordsee, Oeversee, Dueppler Schanzen, 1991.