First Schleswig War
The First Schleswig War, also known as the Schleswig-Holstein uprising and the Three Years' War, was a military conflict in southern Denmark and northern Germany rooted in the Schleswig–Holstein question: who should control the Duchies of Schleswig, Holstein and Lauenburg, which at the time were ruled by the king of Denmark in a personal union. Ultimately, the Danish side proved victorious with the diplomatic support of the great powers, especially Britain and Russia, since the duchies were close to an important Baltic seaway connecting both powers.
While Schleswig had been predominantly Danish with a German elite concentrated in the cities and estates, modernisation brought extensive German influence. German became the language of administration, education, and the church, creating an environment in which it was omnipresent and speaking Danish offered no advantages. Due to top-down pressure, many Danish South Schleswigers gradually adopted German in their daily lives. This linguistic shift led to the extinction of the two Danish South Schleswig dialects, Fjoldemål and Angeldanish – first in favour of Low German, and later High German. Over time, these now Low German-speaking South Schleswigers became fully Germanized, came to identify with the German question, and sought to separate Schleswig, along with Holstein, from Denmark entirely. Therefore, by the outbreak of the war, Schleswig was divided: a Danish-speaking North and a Low German-speaking South, while Holstein and Lauenburg were entirely ethnically German.
In March 1848, the Low German-speaking population of Schleswig, Holstein, and Lauenburg rebelled, and created a provisional government and army. As Holstein and Lauenburg were member states, the German Confederation supported the rebels as a federal war according to its statutes. This was continued by the German Central Government, with most of the German troops being provided by Prussia.
The war was interrupted in August 1848 by the armistice of Malmö, but started again with a Danish offensive in February 1849. In summer 1850, Prussia had to back down and leave the rebels to their fate. On 1 April 1851, the Schleswig-Holstein army was disbanded. The London Protocol of 1852 was the final settlement of the conflict with the great powers confirming the Danish king to be the duke of the duchies but also declaring that the duchies had to remain independent from Denmark proper.
Background
At the beginning of 1848, Denmark included the Duchy of Schleswig, and the king of Denmark ruled the duchies of Holstein and Saxe-Lauenburg within the German Confederation. The majority of the ethnic Germans in Denmark lived in these areas. Germans made up a third of the country's population, and the three duchies accounted for half of Denmark's economy. The Napoleonic Wars, which had ended in 1815, had fanned both Danish and German nationalism. Pan-German ideology had become highly influential in the decades prior to the wars, and writers such as Jacob Grimm and the Norwegian Peter Andreas Munch argued that the entire peninsula of Jutland had been populated by Germans before the arrival of the Danes and that therefore Germans could justifiably reclaim it. Jens Jacob Asmussen Worsaae, an archaeologist who had excavated parts of the Danevirke, countered the pro-German claims, writing pamphlets which argued that there was no way of knowing the language of the earliest inhabitants of Danish territory, that Germans had more solid historical claims to large parts of France and England, and that Slavs by the same reasoning could annex parts of eastern Germany.The conflicting aims of Danish and German nationalists contributed to the outbreak of the First Schleswig War. Danish nationalists believed that Schleswig, but not Holstein, should be a part of Denmark, as Schleswig contained a large number of Danes, whilst Holstein did not. German nationalists believed that Schleswig, Holstein, and Lauenburg should remain united, and their belief that Schleswig and Holstein should not be separated led to the two duchies being referred to as Schleswig-Holstein. Schleswig became a particular source of contention, as it contained a large number of Danes, Germans, and North Frisians. Another cause of the war was the legally questionable change to the rules of ducal succession in the duchies.
King Christian VIII of Denmark died in January 1848. His only legitimate son, the future Frederick VII, seemed unable to beget heirs. Thus the duchies appeared likely to pass to the rule of the House of Oldenburg, which might have resulted in a division of Denmark. Accordingly, Christian VIII had decreed a change to the succession law in the duchies to allow succession through the female line. The implementation of this law was illegal.
The question of Schleswig-Holstein was also a major concern of the other European powers. In order to maintain access to the Baltic, the British Foreign Secretary Lord Palmerston preferred that control of the Danish straits linking the North Sea to the Baltic Sea not be controlled by any major European power such as Prussia. From Palmerston's viewpoint, having a relatively weak power such as Denmark maintain control of the Danish straits was far preferable to having a strong power, and as such Britain tended to support the Danish claims, believing that a Danish-Prussian war might lead to Prussia annexing not just the two duchies, but also all of Denmark. Likewise, Emperor Nicholas I of Russia supported Denmark as he did not want a strong power controlling the Danish straits. Nicholas also believed that if Denmark were defeated even without being annexed, it might lead to the Danes joining a Scandinavian Union that would pose a potential threat to the ability of the Baltic fleet of the Imperial Russian Navy to leave the Baltic. France, the European power most opposed to German unification, was due to the revolution of 1848 unable to take a strong stand on German affairs. The Austrian empire, Prussia's rival for the ascendency in German affairs, was paralyzed as revolts had broken out against the House of Habsburg in Prague, Milan, Buda, Krakow, and in Vienna itself.
In Berlin, the foreign policy decision-making was described as "chaotic" with the weak and indecisive King Fredrich Wilhelm IV receiving conflicting advice from rival groups of advisers about what to do. However, in the aftermath of the revolution of 1848, which had damaged the prestige of the House of Hohenzollern as fighting had broken out in the streets of Berlin, it was felt essential to take a bold foreign policy step which would restore the prestige of the Prussian state. The king and his advisors were not German nationalists, but the German liberals opposed to the absolutist Prussian monarchy were. The king's advisors believed that a German nationalist war would win support for the Prussian state from many of those liberals who were opposed to it.
In addition, the chaos of the revolution of 1848 was felt to offer a unique opportunity to create a greater Prussia by seizing territory, all the more as France was unable to act. However, the king and his advisers were not prepared to risk a general European war over the Schleswig-Holstein question. Joseph von Radowitz, the king's most trusted adviser, wrote in his diary: "The present political-military crisis cannot drag on, it must come to a rapid conclusion". Radowitz was prepared to support a war provided it would be brought to a victorious conclusion swiftly, which would allow Prussia to present the other European powers with a fait accompli. Knowing of the intense Russian opposition to Prussia controlling the Danish straits, Radowitz advised the king to limit the war to the two duchies and not allow Prussian troops to enter Jutland, which he predicted would lead to "unforeseeable consequences" as it was likely that Russia would intervene. The Prussian Foreign Minister Heinrich Alexander von Arnim supported war, believing that Prussia could occupy the two duchies within eight days, leaving Britain and Russia no time to react.
Both Russia and Britain were opposed to Denmark losing control of the Danish straits, but were otherwise supportive of Prussia. Palmerston supported a stronger Prussia and even a Germany unified under Prussian leadership as a way of weakening France. King Fredrich Wilhelm's sister was married to the Emperor Nicholas I, and the Prussian king believed that his brother-in-law could be persuaded to accept Prussia seizing control of the two duchies. Furthermore, Nicolas was well known to be an intense admirer of Prussian militarism and saw Prussia as the stronger ally in the so-called informal "eastern bloc" that consisted of Russia, Prussia, and Austria. The emperor saw Prussia as the more reliable partner in opposing Polish nationalism than the Austrian empire, hence his preference for Prussia over Austria in the "eastern bloc". Nicholas had long made it known that he viewed a Prussian-dominated Germany as a welcome development, which he saw as a way of weakening France, the nation that he hated and feared the most. Fredrich Wilhelm did not want to risk a confrontation with either Britain or Russia, and was only persuaded to act when convinced a war would not cause such a confrontation.