Everyone is talking about the 150th anniversary of the War of 1864. The characters on Borgen will re-enact it. There’s a campaign to renovate Dybbøl Mølle, the site of a crucial battlefield of the war. There’s new best selling historiography. There’s the requisite counterfactual history. There is, of course, a live blog, from which I stole the map above.
Let’s set the scene: from 1815 to 1864, the Danish Monarchy—that is, the lands that were reigned in personal union by the King of Denmark—consisted of the Kingdom of Denmark and various territories to the southwest of the Kingdom on the European continent, as well as assorted North Atlantic and West and East Indian possessions. (Today, the Danish monarch only reigns over the Kingdom, which also includes Greenland, previously a colony.) The full title of the monarch was:
By the Grace of God King of Denmark, the Wends and Goths, Duke of Slesvig, Holsten, Stormarn, Ditmarsken, Lauenborg and Oldenborg
German was spoken in most of the duchies except the northern half of Slesvig. Slesvig was an ancient Danish fief, but the other duchies were part of the Holy Roman Empire and later the German Confederation, with the Danish monarch sending a representative to the Bundestag in Frankfurt.
There had been a war in 1848–50 when Danish troops suppressed a German separatist rebellion. A crisis was brewing in the early 1860s, however: First, there was a succession crisis with the coming death of the childless Frederik VII. But Slesvig and Holsten were supposed to be subject to Salic law, so it would appear that they could not be inherited by the the later Christian IX of the House of Lyksborg. A rival claim was announced by the House of Augustenburg, whose head claimed the title “Duke of Schleswig–Holstein”. As Christopher Clark points out in Iron Kingdom, this looked like “an old-fashioned dynastic crisis, triggered, like so many seventeenth and eighteenth-century crises, by the death of a king without male issue. In this sense, we might call the conflict of 1864 ‘the War of the Danish Succession’.”
The memory of the war survives mainly in the context of the Danish and German nationalist movements. The Danish nationalists wanted to annex Slesvig—whose population was roughly half Danish—into the Kingdom and leave Holsten as a separate state in the Monarchy, thus violating a possibly misunderstood convention that Slesvig would not be placed constitutionally closer to Denmark than Holsten. The ascendant German nationalist movement definitely didn’t approve of that. The efforts culminated in November 1863 in a joint constitution for the Kingdom and Slesvig; the slogan for the movement was “Denmark to the Eider,” the river that formed the southern boundary of the Duchy of Slesvig.
SPOILER ALERT Denmark lost, of course, and had to give up all of the duchies, not just the German speaking parts, up to Kongeåen. The Danish speaking parts returned after the First World War and a referendum in 1920.
That was a lot of scene setting for the question of the day: why didn’t Denmark get its lost territories back after World War II?
The boring answer is that nobody wanted it. There was no appetite for a binational state in Denmark, with possibly violent resistance from the Germans in it. You might have thought that the Germans (with whatever the opposite of 20/20 hindsight is) would have wanted to throw their hat in with a country that had not just lost a world war and would be under military occupation for the indefinite future, but no. There was some whispering, though, and a prime minister lost his job because of it, but even he only wanted to go to the Eider, not the River Elbe, where the Danish monarchy ended in 1863.
A slightly less boring answer is that it would have required a small, but non-trivial, round of ethnic cleansing.
How would a Denmark to the Elbe have looked?
We have to decide whether the Kingdom itself would expand to the Elbe, or whether a union would be established with each part of the Monarchy as a semi-independent state along the lines of, well, Germany. We can imagine a federal state consisting of Denmark, Slesvig, Holsten and the smaller duchies, Greenland and the Faroe Islands. You might even have pulled off an expanded Danish Monarchy without ethnic cleansing. The real post-1945 diplomatic coup would be to convince the Allies to include Hamburg in this federation as a Free (and Hanseatic!) City.
In this scenario, the most important and consequential objection to Denmark-to-the-Elbe—that we would have to drive all the way to Hamburg to buy cheap German booze—would not necessarily apply because Slesvig–Holsten might still have lower taxes on alcohol than Denmark proper.