Second Schleswig War

• 1. Introduction

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  The Second Schleswig War opened with an ultimatum. On the 16th of January 1864, Prussia's minister-president Otto von Bismarck gave Denmark 48 hours to abolish its new November Constitution. Denmark refused. On the 1st of February 1864, Prussian and Austrian troops crossed into the Danish duchy of Schleswig. Denmark stood alone against the combined weight of the Kingdom of Prussia and the Austrian Empire, both acting for the German Confederation. By autumn, the fighting would redraw Denmark's frontier and set two nations on very different paths. What made a decades-old dispute erupt into war in 1864? Why did the great powers Denmark counted on stand aside? And what would each side carry away from the peace that followed?

• 2. A Contested Homeland

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  Schleswig's southern reaches hold the ruins of Hedeby, once a Viking trading capital. Nearby stand the Danevirke earthworks, whose first sections rose sometime between 400 and 500 CE to guard against migrating tribes. Before the Danes settled the area around 500 CE, Schleswig was home to the Angles. Many Angles crossed to Britain and founded the Anglo-Saxon kingdoms there. Those who stayed behind blended with the Danes, a closeness later echoed in sagas the two peoples shared. For Danes, that deep history made Schleswig feel like an inseparable, ancestral part of Denmark.

  Germans pointed to a different set of dates. In 1326 and 1448, Danish kings had accepted Schleswig's near-total independence from the Danish crown. By 1460, a Danish king had promised the duchy would stay forever inseparable, 'up ewich ungedeelt' in the old phrase, from the German duchy of Holstein. Holstein itself was fully German, a fief of the German lands before 1806 and a member of the German Confederation since 1815. Schleswig was more mixed, its people speaking Low German, Danish and North Frisian depending on where they lived.

  In the early 19th century, northern and middle Schleswig still spoke Danish, while the south had shifted to German. German culture dominated the clergy and nobility even in Danish-speaking areas, and Danish carried a lower social status, spoken mostly in rural life. A separate grievance simmered over tolls Denmark charged on ships passing the Danish Straits. Prussia and Austria hoped to sidestep those tolls by building the Kiel Canal, a project impossible so long as Denmark ruled Holstein.

  Much of the dispute turned on who would succeed King Frederik VII, who left no heir the German Confederation found acceptable. Germans in the duchies backed the House of Augustenburg, a cadet branch of the Danish royal family. Most Danes preferred Prince Christian of Glücksburg instead, who had already fought for Denmark in the First Schleswig War of 1848-1852. When Frederik VII died in 1863, that succession quarrel became Otto von Bismarck's opening.

• 3. The Diplomatic Chessboard

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  Otto von Bismarck became Prussia's minister-president in 1862. King Wilhelm I sent him to break a standoff over military spending. Prussia's liberal-dominated Landtag had refused to approve taxes that war minister General von Roon said were needed to modernize the army. Bismarck was known as a gruff bully capable of considerable charm, and clever at solving problems while defending the existing order. When the Landtag still refused, he simply had the Prussian state collect the taxes without its consent, calling it 'a hole in the constitution.' Privately, he admitted the claim was nonsensical.

  In a speech aimed at winning liberal support, Bismarck argued that Germany's problems would be settled by 'blood and iron' rather than talk. Many Prussian liberals were also German nationalists who wanted Schleswig and Holstein folded into a united Germany. Bismarck saw that a war fought in the name of that nationalism could win the liberals to his side and justify the taxes he had collected illegally.

  Russia's calculations had shifted since the First Schleswig War, when the threat of Russian intervention on Denmark's side had twice proved decisive. The Crimean War had turned Russia away from the status-quo policy it upheld under the 1815 Congress of Vienna. Afterward, Russia became a revisionist power, eager to see the European order shift. Tsar Alexander II viewed a stronger Prussia as a useful check on France. That view hardened after Napoleon III took a pro-Polish stance during the Polish Uprising of 1863-1864. Alexander backed Prussia on one condition: that Bismarck promise not to annex Denmark itself, only the duchies.

  British prime minister Lord Palmerston declared in July 1863 that Denmark's independence and rights would be defended. He warned that anyone who attacked them would find that 'it would not be Denmark alone with they would have to contend with.' The speech raised hopes in Denmark of British rescue, but Britain's small volunteer army needed a continental ally it did not have. Anglo-Russian relations remained poisoned by the Crimean War. The American Civil War's 'cotton famine' had also strained ties with Washington, tying up British troops guarding Canada. Palmerston's promise, in the end, was a bluff.

  Napoleon III, widely mistrusted after installing Archduke Maximilian as emperor of Mexico in 1861, took a pro-Prussian line on Schleswig-Holstein. In November 1863 he declared in Paris that 'the compacts of 1815 have ceased to be in force,' and invited European leaders to a congress that never took place. His ambassador in Berlin, Édouard Drouyn de Lhuys, told Bismarck that France would accept Prussia annexing the duchies. In exchange, France wanted the Rhineland. That left Denmark to face the invasion with only its own army and a defensive plan built around the ancient Danevirke line.

• 4. Retreat and Reckoning

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  Danish planners built their defense around three 'flank positions': Ebeltoft in the north, Fredericia in the center, and Dybbøl in the south. The plan used naval supremacy to shift the army quickly, trapping an invader in exhausting marches across Jutland. It was meant to draw out the war long enough for the great powers to intervene, a strategy that had worked in the First Schleswig War. But overconfidence in the army, combined with poor political judgment, overruled that plan. Resources went instead into a frontal defense of the Danevirke line near Schleswig city, leaving the flank positions as simple battlefield works rather than modern fortifications.

  The Danevirke's weakness lay in the water and marsh guarding each end, ordinarily impassable. In early 1864, a hard winter froze those waters solid, letting German forces cross where Danish planners had assumed they could not. A first attempt to bypass the line near Missunde failed. German troops soon appeared in the Danevirke's rear anyway, and the Danish high command judged the line lost.

  On the night of the 5th of February 1864, commander-in-chief Lieutenant General Christian Julius De Meza ordered the Danevirke abandoned. He withdrew the army to Flensburg, defying both government orders and Danish public opinion. The retreat cost 600 men dead or captured, including ten who froze to death, and forced the abandonment of heavy artillery that could not be moved fast enough. De Meza was relieved of command soon after and replaced by General Gerlach.

  Soldiers who lived through the retreat compared it to Napoleon's retreat from Moscow. A north gale drove snow across men who had had no rest in four days. Guns and supply carts, dragged through ice, repeatedly overturned. Pursuing Austrians caught the Danish rearguard at Sankelmark, about eight kilometers south of Flensburg, where Colonel Max Müller's men lost more than 500 before the retreat could continue. Near Oversø, the 9th and 20th regiments of the 8th Brigade lost 600 more, dead, injured or captured, and ten additional soldiers died of hypothermia that same day.

  The army regrouped at a position called 'the old Dybbøl,' which guarded only the tip of a peninsula rather than the road into Jutland. Commanders doubted they could survive a full German siege there, and expected the army to be evacuated by sea instead. Political leaders refused to abandon Schleswig or accept Germany's more modest peace terms. The army was ordered to hold Dybbøl 'to the last man,' and the siege began.

  By August 1864, the King of Denmark had renounced his rights in the duchies. The Treaty of Vienna, signed on the 30th of October 1864, made the cession final. Denmark handed over Schleswig, Holstein and Saxe-Lauenburg to Prussia and Austria, keeping only the island of Ærø, the town of Ribe, and eight parishes from Tyrstrup Herred south of Kolding. The kingdom's land area shrank by 40 percent, and its population fell from 2.6 million to about 1.6 million. When the army came home to Copenhagen, it received no cheering crowds, unlike its victorious return from the First Schleswig War.

• 5. Denmark's Reckoning

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  Prussia and Austria divided the administration of Schleswig and Holstein under the Gastein Convention on the 14th of August 1865, putting roughly 200,000 Danes under German rule. King Christian IX later went behind his own government's back, offering Bismarck a startling deal: all of Denmark would join the German Confederation if Schleswig and Holstein stayed united with it. Bismarck rejected the offer, fearing that ethnic strife between Danes and Germans in Schleswig would stay unresolved either way. The negotiations remained secret until 2010, when the book Dommedag Als by Tom Buk-Swienty revealed them, drawing on royal archives Queen Margrethe II had opened to him.

  The Peace of Prague in 1866 confirmed Denmark's loss of the two duchies but promised a future plebiscite, letting north Schleswig choose to rejoin Denmark. Prussia and Austria unilaterally scrapped that promise in 1878. France's long dominance over Germany's internal power struggles, held since the days of Cardinal Richelieu, ended with this war, opening the path for a rise of Germany that eventually helped bring on the First World War.

  Sweden-Norway's King Charles XV had promised troops but backed out, leaving Denmark to fight alone. Britain's own attempts to mediate the conflict and deter Prussia were also rebuffed, a diplomatic setback for London as well as Copenhagen. The pan-Scandinavian movement, until then aimed at political unification, turned afterward toward shared literature and language instead.

  The defeat shocked Denmark out of treating war as a political option. Danish forces stayed out of conflict beyond their own borders until the NATO bombing of the Federal Republic of Yugoslavia in 1999. That caution shaped Denmark's later 'adjustment policy' and 'cooperation policy' toward Nazi Germany during the occupation of the Second World War.

  Thousands of Danes living in the ceded lands were later conscripted into the Imperial German Army. They suffered heavy losses on the Western Front during the First World War. Resentment lingered for decades in southern Jutland, fading only as the children of conscripted men grew old, and it was the direct reason a German offer of a joint hundredth-anniversary commemoration was turned down in 1966.

  After Germany's defeat in 1918, Denmark asked the Allied Powers at the 1919 Versailles Conference to hold a plebiscite in Schleswig. The request invoked Woodrow Wilson's Fourteen Points, and the Allies granted it. The resulting vote returned North Schleswig to Danish rule, closing a dispute that had run since the 1848 war.

• 6. Bismarck's Legacy

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  After the victory over Denmark, Prussia's liberal-dominated Landtag voted to retroactively legalize the military taxes Bismarck had collected without its consent. Caught up in national celebration, the same chamber that had once resisted him fell in line. British historian Brian Bond later observed that Prussian liberals proved 'extremely susceptible to the appeal of national unity achieved by force of arms.'

  By the years after 1864, most of Bismarck's former liberal opponents had become his supporters, nationalism having outweighed their liberalism. The same illegal taxes that had once made him unpopular were now treated as evidence of his greatness. Bismarck was celebrated, rather than condemned, for violating the 1850 constitution.

  After Bismarck died in 1898, Germany built an outsized personality cult around him, casting him as a superhuman 'great redeemer' of German unification. Writing from exile in France in 1935, diplomat Count Harry Kessler described a German middle class that had grown thoroughly 'Bismarckian.' He said a 'lethal atmosphere' now surrounded anyone critical of the state Bismarck had built.

  Conservatives in the Weimar Republic invoked Bismarck's memory to brand the new democracy as being 'against the spirit of Bismarck.' They cast Weimar's founders, liberals, Social Democrats and the Zentrum party, as the same 'enemies of the Reich' Bismarck had once denounced. Central to that narrative was the claim that Germany needed a Führer, a ruthless dictator, rather than a weak parliament.

• 7. Mercy Amid the Guns

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  The Red Cross movement was founded in 1863, and the Second Schleswig War became its first field test. Both Denmark and Prussia had already formed national Red Cross societies, and the International Committee of the Red Cross sent observers to watch them work. The two societies ran hospitals and treated wounded soldiers from both sides without favor, coverage that reached newspapers well beyond Denmark and Germany. That attention helped draw new volunteers to a movement barely a year old.

• 8. Echoes in Fiction

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  Danish author Herman Bang set his 1889 novel Tine on the island of Als, tracing the war's effects there. The book has since been translated into many languages, including English, and is read as an example of impressionist fiction. Irish novelist Erskine Childers used the war differently in his 1903 novel The Riddle of the Sands. His characters Davies and Carruthers pass a German victory monument at Dybbøl during a stop in Sønderborg. M. R. James worked a line about the war into his ghost story 'Nr. 13.' In it, a character asks, 'Is this the Danish courage I have heard so much of? It isn't a German in there; and if it was, we are five to one.' The Danish television series 1864, broadcast in 2014, dramatized the war for a new generation. The film The Salvation follows a fictional veteran of the conflict who emigrates to America to start over.