The Danish War (1864), or Second Schleswig War, was the first of Bismarck's three wars of German unification, in which Prussia and Austria defeated Denmark and seized the duchies of Schleswig and Holstein, deliberately creating the dispute Bismarck later used to provoke war with Austria.
The Danish War of 1864 (also called the Second Schleswig War) was a short conflict in which Prussia and Austria teamed up to defeat Denmark over two border duchies, Schleswig and Holstein. When Denmark tried to absorb Schleswig directly, Bismarck framed it as an attack on German nationalism and brought Austria along as a partner. Denmark lost quickly, and the Treaty of Vienna (1864) handed the duchies to Prussia and Austria to administer jointly.
Here's the part that matters for AP Euro. Bismarck didn't fight this war because he cared deeply about Schleswig-Holstein. He fought it because joint administration with Austria was a built-in argument waiting to happen. The shared duchies gave him a ready-made pretext for the Austro-Prussian War of 1866, which pushed Austria out of German affairs entirely. The Danish War is Realpolitik in action (KC-3.4.III.B): a calculated, limited war that served the larger goal of unifying Germany under Prussian, not Austrian, leadership.
This term lives in Topic 7.3 (National Unification and Diplomatic Tensions) in Unit 7 and supports learning objective AP Euro 7.3.A, which asks you to explain the factors behind German and Italian unification. The essential knowledge here is KC-3.4.III.B: Bismarck used Realpolitik, combining diplomacy, industrialized warfare, and manipulation of nationalism to unify Germany. The Danish War is step one of his three-war sequence (Denmark 1864, Austria 1866, France 1870-71), so it's your opening evidence whenever a question asks how Germany got unified. It also connects to KC-3.4.II.A, because the Crimean War had already broken the Concert of Europe, meaning no Great Power coalition stepped in to stop Prussia. That diplomatic vacuum is exactly what made Bismarck's wars possible.
Keep studying AP Euro Unit 7
Austro-Prussian War (Unit 7)
The Danish War set the trap; the Austro-Prussian War sprang it. Bismarck made sure Prussia and Austria administered Schleswig-Holstein jointly, then used disputes over that arrangement as his excuse to fight Austria in 1866 and kick it out of German affairs.
Crimean War (Unit 7)
The Crimean War (1853-1856) shattered the Concert of Europe, the system that had kept the post-1815 order stable. With Russia weakened and the Great Powers no longer cooperating, nobody intervened to save Denmark in 1864. Bismarck's wars only worked because the old restraints were gone (KC-3.4.II.A).
Bismarck's Realpolitik (Unit 7)
The Danish War is the textbook example of Realpolitik: war as a cold-blooded tool of state policy rather than ideology. Bismarck wrapped a Prussian power grab in the language of German nationalism, getting nationalists to cheer for a war that mainly served the Prussian state.
Count Camillo Cavour (Unit 7)
Cavour is the Italian parallel you should pair with Bismarck on FRQs. Both used calculated diplomacy and limited wars to unify a fragmented nation under one dominant state (Piedmont-Sardinia for Italy, Prussia for Germany), and the exam loves comparing the two.
The Danish War usually appears in multiple-choice stems testing whether you can identify Bismarck's approach to state building. A typical question pairs the Danish War (1864) with the Austro-Prussian War (1866) and asks what strategy they illustrate. The answer is Realpolitik, using war and diplomacy as pragmatic tools to consolidate Prussian power and exclude Austria from German affairs. No released FRQ has used the term verbatim, but it's strong evidence for any LEQ or DBQ on the causes of German unification or the breakdown of the Concert of Europe. The key move is never to treat it as an isolated war. Always frame it as the first step in Bismarck's deliberate three-war sequence, and you'll earn the analysis points that a bare description won't.
Easy to mix up because both are Bismarck's wars and both involve Schleswig-Holstein. In the Danish War (1864), Prussia and Austria fought together against Denmark and won the duchies. In the Austro-Prussian War (1866), they fought each other over how to run those same duchies. Remember the sequence: allies first, enemies second, and Bismarck planned it that way.
The Danish War (1864) was the first of Bismarck's three wars of German unification, followed by the Austro-Prussian War (1866) and the Franco-Prussian War (1870-71).
Prussia and Austria fought as allies against Denmark and won Schleswig and Holstein under the Treaty of Vienna (1864).
Bismarck deliberately set up joint Prussian-Austrian administration of the duchies so disputes over them could justify war with Austria in 1866.
The war shows Realpolitik in action (KC-3.4.III.B): Bismarck harnessed German nationalist feeling to serve Prussian state power, not the other way around.
The war was only possible because the Crimean War had already destroyed the Concert of Europe, so no coalition of Great Powers intervened to protect Denmark.
It was a short war in which Prussia and Austria defeated Denmark and took the duchies of Schleswig and Holstein. In AP Euro it matters as the first of Bismarck's three wars of German unification and a prime example of Realpolitik (Topic 7.3).
No. Prussia and Austria were allies against Denmark in 1864. They didn't fight each other until the Austro-Prussian War of 1866, when Bismarck used disputes over the captured duchies as his excuse to push Austria out of German affairs.
In the Danish War (1864), Prussia and Austria fought together against Denmark to win Schleswig-Holstein. In the Austro-Prussian War (1866), they fought each other over those same duchies. Bismarck engineered the second war by setting up the joint administration in the first.
Officially to defend German nationals in Schleswig-Holstein after Denmark tried to absorb Schleswig. Strategically, he wanted a popular nationalist cause to boost Prussian prestige and a shared prize with Austria that would later give him a pretext for war against Austria.
Yes, it falls under Topic 7.3 (National Unification and Diplomatic Tensions) and learning objective AP Euro 7.3.A. It typically shows up in multiple-choice questions about Bismarck's Realpolitik and as evidence in essays on the causes of German unification.
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