In diplomacy, the Gastein Convention, also called the Convention of Badgastein, a treaty signed at Bad Gastein in Austria on August 20, 1865,[1] embodied agreements between the two principal powers of the German Confederation, Prussia and Austria, over the governing of the provinces of Schleswig and Holstein. The two powers faced the issue of governing the two provinces when the Treaty of Vienna caused Denmark's cession of the Duchies of Schleswig, Holstein, and Saxe-Lauenburg to Prussia and Austria after the Second War of Schleswig on October 30, 1864. The Peace of Prague in 1866 confirmed Denmark's cession of the two duchies but promised a plebiscite to decide whether north Schleswig wished to return to Danish rule. This provision was unilaterally set aside by a resolution of Prussia and Austria in 1878. Both duchies were to be admitted to the Zollverein (German Customs Union), headed by Prussia, though Austria was not a member.[1]
The eleven articles of the agreement covered:
The Gastein Convention collapsed due to the efforts of Prussian Chancellor Otto von Bismarck to provoke a war with Austria as well as to eliminate Austria from the German Confederation. These efforts led to the outbreak of the Austro-Prussian War, also known as the Seven Weeks' War, in June 1866.