page_title: Duchy of Holstein
section_title: Reunification
hierarchical_section_title: Duchy of Holstein / History / Reunification
caption_attribution_description: Christian VII of Denmark attributed to Nicolai Abildgaard Christian VII forener den hertugelige med den kongelige del af Holsten i 1767. 179
context_page_description: The Duchy of Holstein was the northernmost state of the Holy Roman Empire, located in the present German state of Schleswig-Holstein. It originated when King Christian I of Denmark had his County of Holstein-Rendsburg elevated to a duchy by Emperor Frederick III in 1474. Members of the Danish House of Oldenburg ruled Holstein – jointly with the Duchy of Schleswig – for its entire existence.
  From 1490 to 1523 and again from 1544 to 1773 the Duchy was partitioned between various Oldenburg branches, most notably the dukes of Holstein-Glückstadt and Holstein-Gottorp. The Duchy ceased to exist when the Kingdom of Prussia annexed it in 1866 after the Austro-Prussian War.
context_section_description: In 1713, during the Great Northern War, the estates of the Dukes of Schleswig-Holstein-Gottorp in Schleswig including Schloss Gottorf were conquered by royal Danish troops. In the 1720 Treaty of Frederiksborg, Duke Charles Frederick of Schleswig-Holstein-Gottorp ceded them to his liege lord the Danish crown.
  His remaining territories formed the Duchy of Holstein-Gottorp, administered from Kiel. In 1773, Charles Frederick's grandson, Paul, Emperor of Russia finally gave his Holstein lands to the Danish king, in his function as Duke of Holstein, in exchange for the County of Oldenburg, and Holstein was reunited as a single state.
  With the dissolution of the Holy Roman Empire in 1806, the Duchy of Holstein gained sovereignty.
  After the 1815 Congress of Vienna, the Duchy of Holstein became a member of the German Confederation, resulting in several diplomatic and military conflicts about the so-called Schleswig-Holstein Question. Denmark defended its rule over Holstein in the First Schleswig War of 1848-51 against the Kingdom of Prussia. However, in the Second Schleswig War (1864) Prussian and Austrian troops conquered Schleswig. Christian IX of Denmark had to renounce both Schleswig and Holstein in the Treaty of Vienna (1864) on October 30.  At first placed under joint rule in a condominium, Prussia and Austria then assumed administration of Schleswig and Holstein, respectively, under the Gastein Convention of August 14, 1865. However, tensions between the two powers culminated in the Austro-Prussian War of 1866. Following the Peace of Prague (1866), the victorious Prussians annexed both Schleswig and Holstein by decree of December 24, 1866, and later established the unified Province of Schleswig-Holstein.
caption: Allegorical depiction of Christian VII of Denmark uniting the royal and ducal parts of Holstein, painted by Nicolai Abildgaard
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