"In the early 1860s, Prussia found itself in a favorable foreign policy situation, which made it possible to resolve the issue of German unification. This was largely due to Bismarck ("Germany will be united not by words, but by blood and iron."), who skillfully resolved the Schleswig-Holstein question.
In November 1863, the Danish King Frederick VII died, and his heir, Christian IX, ascended the throne. The question of who owned the duchies of Schleswig and Holstein arose once again. Denmark, to which Schleswig had historically belonged and which laid claim to Holstein, or the German Confederation, since Holstein was a fief of the Holy Roman Empire. Furthermore, the population of both duchies was German.
The First Schleswig War (1848–1850), sparked by the revolution, did not resolve this issue. The status quo was maintained. King Christian IX claimed to have inherited the duchies and attempted to reintegrate the Duchy of Schleswig into Denmark by signing the so-called November Constitution.
The hereditary rights to the Christian duchies were recognized as early as 1852 by all powers, including the Kingdom of Prussia. But the issue was not one of legal and genealogical subtleties…"
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Armand
