The Danish Wars
Two German-Danish Wars intervened to influence the make-up of the German Confederation. In 1815, the province of Holstein was admitted to the German Confederation because the population was ethnically German, despite the fact that the King of Denmark owned it. Schleswig, in contrast, was 50 percent Danish, had never been part of the Holy Roman Empire, and was considered to be an integral part of the Danish kingdom. A third province, Lauenburg, was often considered a small add-on to Holstein. There was a pre-1850 minority movement within Denmark to create an independent state named Schleswig-Holstein. The King of Denmark objected, offered independence to Holstein, but insisted that Schleswig remain closely tied to Denmark and give up its autonomy, thereby losing home rule and linguistic privileges. In 1850 the German Confederation asked Prussia to police Danish notions of hegemony in the region; they were successful until pressed to conclude a truce. The three provinces remained part of Denmark while retaining their local autonomy.
When the King of Denmark, Frederick VII, died in 1863, the Schleswig-Holstein crisis gained in significance. The new Danish king, Christian IX of Schleswig-Holstein-Sonderburg-Glücksburg, a junior branch of the House of Oldenburg, announced his intent to annex Schleswig. Based on the Treaty of the First Danish War in 1850, the duchies were to belong to the new Danish king provided he did not annex them. The Germanic Confederation offered a plan to name Prince Friedrich of Augustenburg as the new Duke of Schleswig-Holstein. While most of the members of the Germanic Confederation supported a new smaller state, Austria and Prussia demanded that Denmark abide by its treaty obligations and not annex any land.
When King Christian of Denmark sent troops into the duchies and attached Schleswig directly to Denmark, Austria and Prussia went to war without the approval of the Confederation because, as has been mentioned, the Confederation supported Prince Augustenburg as Duke. Although the war was originally intended to re-establish home rule in Schleswig, when Denmark lost, the Danes ceded Schleswig, Holstein, and Lauenberg jointly to Austria and Prussia.
With Denmark out of the way, Austria and Prussia agreed to the Gastein Convention. This agreement awarded Schleswig to Prussia and Holstein to Austria. Austria also agreed that any dispute about the provinces would be handled purely as a matter for Prussia and Austria to resolve. The Austrian-dominated German Confederation would not be involved. Austria agreed to sell Lauenburg to the Prussians and to allow Prussia the use of Holstein’s roads and telegraph facilities.
A popular notion is that Bismarck went to war against Denmark in 1864 to engineer unification of the Confederation. When Denmark lost, Bismarck was able then to contrive a war between Prussia and Austria over the governance of the newly acquired provinces. While some believe this stratagem was his intent, it was a complex issue made even more so because of the number of players. Most agree that it would have been difficult for one man to engineer the outcome.