Danish-Prussian War Summary

  • Last updated on November 10, 2022

Prussia and Austria invaded the autonomous Danish duchies of Schleswig and Holstein in order to further their German nationalist agendas. The resulting war not only determined the future of the two provinces but also influenced the drive toward German unification, helping Prussia eclipse Austria as the dominant German state.

Summary of Event

Positioned in north-central Europe at the base of the Jutland Peninsula, the duchies of Schleswig and Holstein found themselves caught in the power struggles of the nations surrounding them. As a result, they were often pawns in the political struggles of much larger powers. In 1460, the provinces of Holstein and the duchy of Schleswig formed a personal union (Holstein became a duchy fourteen years later). The union placed itself under the protection of Christian I Christian I of Denmark, which began the long history of Danish suzerainty over the region. Most of the population of the duchies at that time were of Danish descent, and for most of the next four centuries, the two duchies remained autonomous regions within the Danish state. Danish-Prussian War (1864)[Danish Prussian War (1864)] Prussia;Danish-Prussian War[Danish Prussian War] Denmark;Danish-Prussian War[Danish Prussian War] Holstein [kw]Danish-Prussian War (Feb. 1-Oct. 30, 1864) [kw]Prussian War, Danish- (Feb. 1-Oct. 30, 1864) [kw]War, Danish-Prussian (Feb. 1-Oct. 30, 1864) Danish-Prussian War (1864)[Danish Prussian War (1864)] Prussia;Danish-Prussian War[Danish Prussian War] Denmark;Danish-Prussian War[Danish Prussian War] Holstein Schleswig-Holstein War (1864);Danish-Prussian War [g]Germany;Feb. 1-Oct. 30, 1864: Danish-Prussian War[3710] [g]Scandinavia;Feb. 1-Oct. 30, 1864: Danish-Prussian War[3710] [g]Denmark;Feb. 1-Oct. 30, 1864: Danish-Prussian War[3710] [c]Wars, uprisings, and civil unrest;Feb. 1-Oct. 30, 1864: Danish-Prussian War[3710] [c]Expansion and land acquisition;Feb. 1-Oct. 30, 1864: Danish-Prussian War[3710] Bismarck, Otto von [p]Bismarck, Otto von;and Danish-Prussian War[Danish Prussian War Christian IX Frederick VII Frederick VIII (Schleswig and Holstein))

As the decades passed, however, the demographic makeup of Schleswig and Holstein changed, as the population became increasingly Germanic in background. The growing German population demanded more and more autonomy, and, when King Christian VIII Christian VIII died in 1848, a growing independence movement threatened Danish control of the region. To quell this uprising, the new Danish king Frederick VII Frederick VII announced the formal annexation of Schleswig in 1848, causing the population of the two regions to rise up in rebellion. Prussia, seeking greater influence in the German-speaking regions of central Europe, came to the aid of the rebels, precipitating the Three Years’ War.

Despite initial setbacks, Denmark managed to drive out the Prussians and quell the rebellion the following year. In 1851, the London Protocol London Protocol (1851) returned the region to its prerevolutionary status quo, with Schleswig and Holstein as autonomous regions administered by Denmark. To quell demands for independence, the London Protocol removed from power Frederick VIII of Schleswig and Holstein, the leader of the ruling family of the duchy of Holstein and a leader in the independence movement.

Nationalist passions, however, continued to swell during the mid-nineteenth century. A growing German nationalism demanded that a unified Germany be built from the patchwork of duchies and baronial estates of the old German Confederation. Nationalism bred competition, however, with Prussia and the Austrian Empire each attempting to lead the growing nationalist sentiment and to become the leader of a potential German state. Both Austria and Prussia considered Schleswig and Holstein to be part of a future Germany, and Prussia particularly wanted to avenge its failure in 1849. In Denmark, nationalism was also running high, as the Danes sought to preserve their nation’s territorial integrity against what they saw as an expansionistic Prussia on its eastern border. Demands for the formal annexation of Schleswig and Holstein to Denmark continued as a way to assert Danish claims, end talk of separatism in the two provinces, and forestall Prussian ambitions.

When Frederick VII Frederick VIII (Schleswig and Holstein)) died in 1863, his son, King Christian IX Christian IX , a supporter of the nationalist movement, persuaded the Danish parliament to modify the constitution and approve the formal annexation of Schleswig in violation of the London Protocol. To placate German sentiment, Denmark granted Holstein its independence, and Frederick VIII returned to claim his previous title. Otto von Bismarck Bismarck, Otto von [p]Bismarck, Otto von;and Danish-Prussian War[Danish Prussian War , prime minister of Prussia and architect of the future German state, saw an opportunity to redress previous failures to acquire Schleswig and Holstein. With the rest of Europe remaining neutral because of Danish violations of the protocol, Bismarck procured an alliance with Austria. They sought to seize Schleswig from Denmark and to depose Prince Frederick and wrest Holstein from him. Austria was initially inclined to seek a negotiated settlement, but with Prussia determined to use force, Austria had to join in a military attack or look weak compared to its rival for leadership of the German-speaking peoples.

Thus, on February 1, 1864, Prussia and Austria together invaded Schleswig and Holstein. The war went badly for the Danes from the start. The forty-thousand-man Danish army, equipped with a variety of outdated weaponry, faced the combined armies of Prussia (forty-three thousand troops) and Austria (twenty-eight thousand troops), which were armed with the latest weapons technology, including breech-loading rifles. Denmark was forced to defend a long defensive line across the entire length of Schleswig, while the Prussian-Austrian army could make concentrated attacks at vital points.

In April, the Prussians and Austrians broke through the Danish defensive lines and defeated the Danes at the Battle of Dybböl on April 18 after a six-week siege. The Danes retreated to the Fredericia Fortress, which had withstood a Prussian assault in 1848. This time, however, the Prussians came equipped with heavy siege artillery, and the fortress could not withstand their assault. Pounded into submission, the Fredericia Fortress surrendered on April 29. After the fall of the fortress, England attempted to negotiate an end to the conflict, but neither side proved willing to negotiate. The Prussians and Austrians were winning the war, and thus were little inclined to grant concessions. Denmark, while in the losing position, refused to grant territorial concessions and insisted that it was the Austrians and Prussians who were the aggressors. The peace talks ended without achieving a cease-fire.

While Prussian and Austrian troops pressed their attack up the Jutland Peninsula, the Prussians conducted a landing on the island of Als, and, despite a heroic defense, the Danes suffered another defeat. With the Prussians and Austrians now deep in Danish territory, the Danes could do nothing but sue for peace. On October 30, Denmark signed the Treaty of Vienna. In the treaty, the Danes ceded Schleswig to Prussia and Holstein to Austria. In addition, Denmark surrendered its own province of Lauenburg to Prussia. The cessions meant that Denmark lost 40 percent of its prewar land area and 20 percent of its prewar population. Denmark was also made to pay reparations to the Prussians and Austrians in the amount of 20 million dalers. Danish casualties in the war totaled 14,460 (including 3,151 dead). The Prussian casualties amounted to 3,356 (1,048 dead), while the Austrians suffered 1,164 casualties (671 dead).


The end of the war did not bring peace to the region. Austria and Prussia soon argued over the future of the conquered territories. Prussia wanted the two former duchies to be annexed into a greater German state, while Austria, now fearful of Prussian expansionism, favored a unified but independent Schleswig and Holstein. The debate over the future of the region led to the Seven Weeks’ War of 1866, Prussia;Seven Weeks’ War[Seven Weeks War] Seven Weeks’ War (1866)[Seven Weeks War (1866)] in which Prussia decisively defeated Austria. Prussia subsequently annexed Schleswig and Holstein and emerged as the dominant force in the German nationalist movement, leading to a unified German Empire in 1871.

The Danish-Prussian War set in motion a series of events that shook Europe over the next several decades. With its success in the conflict, Prussia surpassed Austria as the greatest power in central Europe. The war also empowered Prussia to carry forward its campaign of unification, leading to the creation of modern Germany. That creation, however, could only occur after the defeat of France in the Franco-Prussian War (1870-1871), but the bitterness of that war led directly to World War I (1914-1918) and World War II (1939-1945). Thus, a minor territorial dispute helped set in motion a series of cataclysmic events.

Denmark never stopped pressing its claim on Schleswig. After the German defeat in World War I, a plebiscite was finally held to determine Schleswig’s future in 1920. A majority voted for reunification with Denmark, and the northern portion of the region reverted to Danish control, becoming South Jutland. The remainder of the region became a state of West Germany in 1946. After the German reunification of 1989, the non-Danish portion of Schleswig and all of Holstein became a state in Germany called Schleswig-Holstein.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Bucholz, Arden. Moltke and the German Wars, 1864-1871. New York: Palgrave, 2001. A detailed examination of the mechanisms of the German army as an instrument of national unification.
  • citation-type="booksimple"

    xlink:type="simple">Carr, William. The Origins of the War of German Unification. New York: Longman, 1991. A broad discussion of the violent unification of Germany by examining the various wars that created the nation.
  • citation-type="booksimple"

    xlink:type="simple">Nielsen, Johs. The Schleswig-Holstein Revolt, 1848-1850. Copenhagen: Tojhusmuseet, 1993. A very brief history of the revolt that triggered the Danish-Prussian War a decade later.
  • citation-type="booksimple"

    xlink:type="simple">Van der Kiste, John. Northern Crowns: The Kings of Modern Scandinavia. Stroud, England: Sutton, 1996. Includes useful biographies of Denmark’s kings, including Christian IX.

Organization of the German Confederation

Bismarck Becomes Prussia’s Minister-President

North German Confederation Is Formed

Austria and Prussia’s Seven Weeks’ War

Franco-Prussian War

German States Unite Within German Empire

Related Article in <i>Great Lives from History: The Nineteenth Century, 1801-1900</i>

Otto von Bismarck. Danish-Prussian War (1864)[Danish Prussian War (1864)] Prussia;Danish-Prussian War[Danish Prussian War] Denmark;Danish-Prussian War[Danish Prussian War] Holstein

Categories: History