Belligerents:

Denmark.
Prussia and Austria.

Cause:

The strong revival of nationalism in Germany after the Napoleonic Wars spread to the German inhabitants of the Duchies of Schleswig Holstein, who desired in 1848 to be incorporated as a single constitutional state in the German Federation. The Danish crown could be inherited by female heirs, but in the Duchies the Salic law had never been repealed. This made complications with regard to the succession. Frederick VII of Denmark endeavoured to preserve the Duchy as an integral part of Denmark. An insurrection broke out, and Prussia intervened by marching troops into Holstein. Under pressure from other Powers the King of Prussia signed a convention at Malmoe practically yielding all the Danish demands, and in 1850, by the Treaty of Berlin, peace was restored between Prussia and Denmark, but without any settlement of the vexed question. In 1852 Great Britain intervened with a proposal without success. In 1854 the King of Denmark promulgated special Constitutions for the Duchies as well as a common Constitution for the whole Monarchy. The German Confederation rejected this as the Diets of the Duchies had not been consulted. The question became of European interest: its complexity prevented any settlement being reached. Bismarck alone was quite determined on eventual annexation, and Denmark was equally determined not to yield.

Occasion:

After further diplomatic disputes Austrian and Prussian troops entered Schleswig in February 1864.

Course of the War:

The allied troops broke through the frontier fortifications and occupied the greater part of the Danish mainland. The Danes were overthrown in the island of Alsen, and the German flag carried to the northern extremity of Denmark. A conference was opened in London, April 1864, but the negotiations broke down and the war continued.

Political Result:

Eventually, by the Treaty of Vienna, October 30, 1864, the King of Denmark ceded the rights in the whole of Schleswig Holstein to the Sovereigns of Austria and Prussia jointly.

Remarks:

This was more a diplomatic war than a military war. The conflict was between retention and annexation, and little regard was paid on any side to the desires of the inhabitants of the disputed territory. Although by the Treaty of London of 1852 the Powers, including Great Britain, had acknowledged as permanent the principle of the integrity of the Danish Monarchy no steps were taken by them to maintain that principle. The settlement did nothing to prevent the outbreak of war between Prussia and Austria two years later, when Schleswig Holstein was again one of the bones of contention.