The Duchy of Holstein was established by a Scandinavian monarch under what union?
Duchy of Holstein The Duchy of Holstein (German: "Herzogtum Holstein" , Danish: "Hertugdømmet Holsten" ) was the northernmost state of the Holy Roman Empire, located in the present German state of Schleswig-Holstein. It was established when King Christian I of Denmark had his County of Holstein-Rendsburg elevated to a duchy by Emperor Frederick III in 1474. Holstein was ruled jointly with the Duchy of Schleswig by members of the Danish House of Oldenburg for its entire existence.
Margaret I of Denmark Margaret I (Danish: "Margrete Valdemarsdatter" , Norwegian: "Margrete Valdemarsdatter" , Swedish: "Margareta Valdemarsdotter" , Icelandic: "Margrét Valdimarsdóttir" ; 1353 – 28 October 1412), was queen consort of Norway 1363-1380 and Sweden 1363-1364, and later ruler in her own right of Denmark, Norway and Sweden, from which later period there are ambiguities regarding her specific titles. She was the founder of the Kalmar Union, which spanned Scandinavia for over a century. Margaret was known as a wise, energetic and capable leader, earning the nickname "Semiramis of the North", or "the Lady King". Though the latter was a derisive nickname invented by her rival Albert of Mecklenburg, it became widely used in recognition of her capabilities.