Danish War

The Danish War (also called the Second Schleswig War, February–October 1864) was the first of the three "wars of unification" engineered by the Prussian Minister-President Otto von Bismarck, who took office in 1862. Its immediate trigger was the Danish king Christian IX's promulgation in November 1863 of the so-called November Constitution, which sought to incorporate the duchy of Schleswig into the Danish kingdom in violation of the London Protocol of 1852. That protocol, signed by the major European powers, had affirmed the integrity of the Danish monarchy while preserving the distinct status of the German-speaking duchies of Schleswig, Holstein, and Lauenburg. By invoking the breach of an internationally guaranteed treaty, Bismarck cloaked an expansionist war in the language of legality and the German nationalist cause, simultaneously denying Denmark the diplomatic support of Britain and France.

The war's central feature was the diplomatic isolation of Denmark and the temporary alliance of the two leading German powers. Rather than allowing the German Confederation's federal forces to act under the smaller states' leadership, Bismarck insisted that Prussia and Austria intervene jointly as great powers, sidelining the nationalist liberals. The decisive military engagement was the Prussian storming of the Danish fortifications at Dybbøl (Düppel) on 18 April 1864, followed by the occupation of Jutland. Denmark, abandoned by the powers it expected to defend the London Protocol, sued for peace. The Treaty of Vienna (30 October 1864) compelled Denmark to cede Schleswig, Holstein, and Lauenburg to the joint administration of Prussia and Austria.

The settlement deliberately created a condominium ripe for future quarrel. The Convention of Gastein (14 August 1865) divided administration—Prussia governing Schleswig, Austria governing Holstein, and Prussia purchasing Lauenburg—an arrangement Bismarck himself described as merely "papering over the cracks." The friction over the duchies' administration became the calculated pretext for the Austro-Prussian (Seven Weeks') War of 1866, in which Prussia expelled Austria from German affairs at the Battle of Königgrätz (Sadowa) and absorbed Schleswig-Holstein outright. Thus the Danish War is correctly read not as an isolated event but as the opening move in the unification of Germany completed by the Franco-Prussian War of 1870–71 and the proclamation of the German Empire at Versailles in January 1871. A plebiscite finally returned northern Schleswig to Denmark only in 1920 under the Treaty of Versailles.

For the UPSC World History paper (and the General Studies Mains coverage of nineteenth-century nationalism), the Danish War is examined chiefly as the first stage of Bismarckian Realpolitik and German unification. Typical question angles ask candidates to sequence the three unification wars (1864, 1866, 1870–71), to assess Bismarck's diplomatic method of isolating each adversary before striking, and to explain how he exploited the Schleswig-Holstein question to draw Austria into a partnership he intended to dissolve. Candidates should connect the war to the broader theme of conservative statesmen harnessing popular nationalism for dynastic and Prussian ends, contrasting Bismarck's calculated diplomacy with the more idealistic unification of Italy under Cavour and Garibaldi.