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.
Eric I, Duke of Schleswig Eric I Abelsøn (died 27 May 1272) was a Danish nobleman. He was the ruling Duke of Schleswig from 1260 until his death in 1272. He was the second son of King Abel of Denmark, Duke of Schleswig and Mechtild of Holstein.