King Christian IX of Denmark signed the November constitution, which declared Schleswig as an integral part of Denmark, prompting immediate backlash from the German Confederation. The German states, citing violations of the London Protocol—a treaty established to preserve peace and delineate the rights to Schleswig—perceived this move as an aggressive expansion of Danish territory. Tensions escalated quickly, as the German Confederation mobilized its military and prepared to defend its interests in the region. This constitution not only altered the political landscape of Northern Europe but also intensified nationalistic sentiments among both Danes and Germans.

The backdrop of this declaration can be traced to the complex history of Schleswig, a region with a mixed population of Danes and Germans. The longstanding cultural and political disputes over the territory reflected broader nationalist movements across Europe during the 19th century. Christian IX’s decision was rooted in Denmark’s desire to unify its territory and counterbalance the rising influence of Prussia in the German states. The resulting conflict, known as the German–Danish War of 1864, would determine the fate of Schleswig and dramatically reshape the political order in Central Europe.

As hostilities broke out, Denmark found itself facing a coalition of German states, primarily led by Prussia and Austria. The war was marked by several key battles, showcasing the superior military organization of the German forces. The conflict culminated in Denmark’s defeat, leading to significant territorial losses and the eventual establishment of German dominance in the region, which would further ripple through European politics leading up to World War I.