Adolf VIII of Schleswig-Holstein

Adolphus XI of Schauenburg (Low German: Alef or Alv, German: Adolf von Schauenburg, Danish: Adolf 8. af Holsten-Rendsborg) (1401 – 4 December 1459), as Adolph I Duke of Schleswig (Danish, Sønderjylland, formerly Slesvig), and as Adolph VIII Count of Holstein-Rendsburg, was the mightiest vassal of the Danish realm.

Adolph descended from a branch of the House of Schauenburg, who had for centuries been counts of Holstein, and as such, vassals of the Holy Roman Empire. His great-grandfather Gerhard the Great, having also been a Regent of the Kingdom of Denmark, had received the Duchy of Sønderjylland from the Danish crown as a hereditary fief. It had been lost for the Schauenburgs between 1330 and 1375, with Queen Margaret I of Denmark restricting the regained ducal power in 1386, and again from 1414 to 1440.

Count Adolph's parents were Gerhard VI, Count of Holstein-Rendsburg and Catherine Elisabeth of Brunswick-Lüneburg. Adolph was only three years old when his father was killed in action against the Ditmarsians in the Battle at Hamme near Heide (today's Schleswig-Holstein), on 4 August 1404. Adolph was educated at the court of Frederick I, Margrave of Brandenburg at Hohenzollern Castle.

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