The Treaty of Vienna was signed on October 30th, 1864 by Denmark, Prussia, and Austria, which put an end to the Schleswig War. Denmark had to give up control of the duchies of Schleswig, Holstein, and Lauenburg to the Prussian and Austrian alliance.

The Treaty of Vienna was signed on October 30th, 1864 by Denmark, Prussia, and Austria, which put an end to the Schleswig War. Denmark had to give up control of the duchies of Schleswig, Holstein, and Lauenburg to the Prussian and Austrian alliance.