Coming into 1863, the conflict between Prussia and Denmark had been escalating for quite some time. The main issue was about the Duchies of Schleswig, Holstein and Lauenburg. Although the population was dominantly German in these regions, they were the territories of the Kingdom of Denmark at the time. As the first step towards the German Unification, Bismarck wanted to “liberate” the Germans in the area and annex them. It wasn’t, however, such an easy task to do so as the British had been backing and supporting Denmark against the Germans for a long time. They wanted to contain German influence in the Baltics by keeping Denmark as a strong regional power.
To circumvent the British threat, Bismarck applied his Realpolitik diplomacy as always: He used the Polish rebellion of 1863 to alienate Russia from Western great powers. Russia became diplomatically outcast in a short time and was only encouraged by Prussia. Thus, these two nations created an informal alliance. Bismarck now could wage war against Denmark as he wished, since the British wouldn’t take the risk of fighting against an alliance of Prussia and Russia. Still, the British never officially withdrew their support from Denmark. Confident with the supposed British support, Denmark refused to back up against Prussia. This caused the entire German Confederation, including Austria, to side with Prussia in the quest to liberate the Germans in the area.
On 19 February 1964, Prussia and Austria declared war on Denmark. The British immediately asked both the French and the Russians to intervene but both sides rejected. Fearing of a diplomatic isolation, the British refrained from intervening as well. At the start of the war, the German side had the absolute superiority in manpower and cannons. After a few small battles in the Schleswig-Holstein region, the Danish Army was forced to retreat all the way to Dybbøl. The amount of territory Denmark gave up without fighting was huge and the retreat wasn’t well-organized either. It cost many casualties among the army. Prussian Army reached Dybbøl in mid-April and stormed the Danish positions. The outcome was a clear and decisive Prussian victory. The swift victories of the Germans was so alarming to Brits that they called for a conference in London with the participation of Prussia, Austria, Denmark, Russia and France.
London Conference lasted until June and as no one wanted to face up directly against a unified German coalition, all sides remained neutral. From April to June, during the entire Conference, the war was ceased and Germans didn’t advance further into Denmark. As the Conference ended on 22 June without a proper conclusion, Prussia and Austria made an agreement to completely separate the German Duchies from Denmark. On 29 June, Germans caught the Danish forces and defeated them once again at the Battle of Als. In July, Prussians managed to invade almost the entire Jutland region of Denmark. It became quite clear that the war was lost. King of Denmark renounced all his claims and rights from the German duchies at the beginning of August and accepted peace negotiations.
With the Treaty of Vienna, on 30 October 1864, Denmark officially ceded Schleswig, Holstein and Lauenburg to Prussia and Austria. The future of these duchies later became a big problem between Prussia and Austria. Initially, Schleswig was annexed by Prussia and Holstein was annexed by Austria. Lauenburg was purchased by the Prussians from Austria. Yet the power dynamics within German Confederation and the conflict of German Dualism was forcing its limits. In 2 years’ time, these two sides fought another bloody battle but this time between themselves and shaped the destiny of Germany forever.
For Prussia, this was the first war since the reorganization. The army and military staff definitely proved capable and showed signs of their future glorious victories. The Second Schleswig War is considered the first step to the Unification of Germany, which was concluded in 1871 with the coronation of Wilhelm as the German Kaiser. Prussia gained confidence, proved effective both diplomatically and militarily, while gaining a vast amount of territory and population. The next decade brought even more glory and fame to Prussia and Prussian Army.