Schleswig-Holstein Question

The Schleswig-Holstein Question (German: Schleswig-Holsteinische Frage; Danish: Spørgsmålet om Sønderjylland og Holsten) was a complex of diplomatic and other issues arising in the 19th century from the relations of two duchies, Schleswig (Danish: Sønderjylland/Slesvig) and Holstein (Danish: Holsten), to the Danish crown and to the German Confederation. The British statesman Lord Palmerston is reported to have said: “Only three people...have ever really understood the Schleswig-Holstein business—the Prince Consort, who is dead—a German professor, who has gone mad—and I, who have forgotten all about it."

Schleswig was a part of Denmark during the Viking Age, and became a Danish duchy in the 12th century. Denmark repeatedly tried to reintegrate the Duchy of Schleswig into the Danish kingdom. On March 27, 1848 Frederick VII of Denmark announced to the people of Schleswig the promulgation of a liberal constitution under which the duchy, while preserving its local autonomy, would become an integral part of Denmark. This led to an open uprising by Schleswig-Holstein's large German majority in support of independence from Denmark and of close association with the German Confederation. The military intervention of the Kingdom of Prussia supported the uprising: the Prussian army drove Denmark's troops from Schleswig and Holstein in the First Schleswig War of 1848–1851. The second attempt to reintegrate the Duchy of Schleswig into the Danish kingdom, initiated by the signing by King Christian IX of Denmark of the November Constitution in 1863, was seen as a violation of the London Protocol and led to the Second Schleswig War of 1864.

Even though Schleswig, Holstein, and Denmark had all had the same hereditary ruler for some centuries, the inheritance rules in the three territories were not quite the same. The Dukedoms of Schleswig and Holstein were inherited under the Salic law which ignored females: the Kingdom of Denmark had a slightly different inheritance law which included male heirs inheriting through the female line. In the 19th century this slight difference in inheritance law meant that when the childless King Frederick VII of Denmark died the Kingdom of Denmark would be separated from the duchies of Schleswig and Holstein because two different people would inherit the Kingship and Dukedoms. This finally happened on the death of Frederick in 1863.

The central question was whether the duchy of Schleswig was or was not an integral part of the dominions of the Danish crown, with which it had been associated in the Danish monarchy for centuries or whether Schleswig should, together with Holstein, become an independent part of the German Confederation. Schleswig itself was a fiefdom of Denmark, as the duchy of Holstein had been a fief of the Holy Roman Empire until 1806, and become a component state of the German Confederation with the Danish king as duke. This involved the question, raised by the death of the last common male heir to both Denmark and the two duchies, as to the proper succession in the duchies, and the constitutional questions arising out of the relations of the duchies to the Danish crown, to each other, and of Holstein to the German Confederation.

Much of the history of Schleswig-Holstein has a bearing on this question: see history of Schleswig-Holstein for details. Following the defeat of Germany in World War I, the Danish majority area of Northern Schleswig was finally unified with Denmark after two plebiscites organised by the Allied powers. A small minority of ethnic Germans still lives in Northern Schleswig, whereas a Danish minority remained in South Schleswig.