Treaty of Vienna ends the Second Schleswig War, 30 October 1864

Background. The conflict arose from the November Constitution of 1863, which integrated Schleswig with Denmark. The German side viewed this as a violation of the London Protocol. Bismarck, under domestic pressure since a 1862 constitutional crisis, hoped to gain public support among Prussian liberals by achieving the "liberation" of Schleswig. The war began in February 1864 when Prussian and Austrian forces crossed into Schleswig, initiating hostilities against Danish defenses.

Diplomatic Context. The London Conference failed to reach a conclusion in June 1864. Preliminary peace terms were signed in August, where the Danish King renounced rights in the duchies. These preliminaries paved the way for the final treaty. The diplomatic landscape was shaped by failed negotiations and military pressure, leading to the formal cession of territory.

Aftermath. The treaty established joint administration of the duchies. The Gastein Convention of 1865 divided administration between Prussia and Austria. Disputes over these territories contributed to the Austro-Prussian War of 1866. The Peace of Prague in 1866 confirmed the cession but promised a plebiscite for north Schleswig, which was not fulfilled.