We need not go back further than 1846, when King Christian of Denmark declared the right of the Crown to Schleswig-Holstein. His son and successor, Frederick VII, on his accession in January, 1848, proclaimed a new constitution uniting the duchies more closely with Denmark. This step caused an insurrection and the foundation of a provisional government. Prussia thereupon came to the help of the duchies and defeated the Danes near Dannawerke. After a fruitless attempt at intervention by the Powers, hostilities were renewed, and in April, 1849, the Danes were victorious over the Holsteiners and Germans. There was further fighting and further diplomacy, until in July, 1850, the integrity of Denmark was guaranteed by England, France, Prussia, and Sweden. This was quickly followed by the defeat of the Schleswig-Holsteiners by the Danes at the battle of Idstedt. Early in the following year the Stadholders of Schleswig-Holstein issued a proclamation placing the rights of the country under the protection of the Germanic Confederation.
This led to the Treaty of London of 1852, by which the possession of the duchies was assured to Denmark conditionally on the preservation of their independence and the rights of the German population in them. Now, Holstein belonged to the Germanic Confederation, but the treaty stipulated that Schleswig was not to be separated from Holstein, though it was a point of honour with Denmark not to give up Schleswig.
The natural successor of King Frederick VII in the duchies was his kinsman, Duke Christian of Sonderburg-Augustenburg, who, in May, 1852, resigned his hereditary claim in return for a sum of two and a half million thalers. This settlement might have been excellent but for two facts—first that it had not received the assent of the Germanic Confederation; and secondly, that Duke Christian’s two sons violently objected to it—indeed, the elder son, the Hereditary Prince Frederick, made a formal declaration of his rights of succession. Moreover, it must be admitted that Denmark showed a cynical disregard of the conditions in the Treaty of London respecting the independence of the duchies and the rights of their German population. The Schleswig Assembly complained and protested, and even petitioned the Prussian Chamber of Deputies, who actually promised aid to the duchies.
At last the crisis came in March, 1863, when the King of Denmark granted to Holstein a new and independent constitution, but annexed Schleswig which did not belong to the Germanic Confederation. Thereupon the Confederation invited Denmark to withdraw this constitution. So far from doing so, however, the Danish Parliament proceeded to ratify it only two days before the death of King Frederick VII, whose successor, King Christian IX, was forced on his accession, owing to a menacing uprising of popular feeling in Denmark, to sign the new constitution annexing Schleswig.
The glove was thus thrown down for Germany to pick up; the Hereditary Prince Frederick assumed by proclamation the government of the duchies, and appealed to the Germanic Confederation for the support of his rights. The majority of the German Governments sided with him, especially the Grand Duke Frederick of Baden, brother-in-law of the Crown Prince; while the Lower House in Prussia declared by a large majority that the honour and interest of Germany demanded the recognition and active support of the Hereditary Prince. It will be evident from what has been said above that Prussia had plausible and even sound reasons for her intervention, the chief of which was the popular feeling prevailing in Schleswig.
Now, it so happened that the Crown Prince and Princess had a strong personal as well as political interest in the question of duchies. The Crown Prince and the Hereditary Prince Frederick were old friends. They had first met as fellow-students at the University of Bonn. The Hereditary Prince had afterwards served in the First Regiment of the Prussian Guards, he had been often at the Prussian Court, and the Crown Prince was the godfather of one of his children. Naturally, therefore, the Crown Prince and Princess were favourable to his claims.
There is now no doubt that Bismarck had some time before resolved in principle on the annexation of the duchies, but of course he did not show his hand until it suited him, and above all he studiously concealed his plans from the Crown Prince. Indeed, the Crown Prince’s personal relations with Bismarck were at this time practically suspended, if only because he happened at the time to be in England, where, however, the prevailing sympathy with Denmark did not influence him or the Crown Princess. In a letter written to Duncker from Windsor in December the Prince says that he has “daily defended the cause of my dear friend Duke Frederick, well backed up by my wife, who exhibits warm and absolutely German feelings in a most moving degree.”