Schleswig
historic and cultural region occupying the southern Jutland Peninsula north of the Eider River and now encompassing the northern half of Schleswig-Holstein Land (state) in northern Germany and Sonderjylland amtskommune (county commune) in southern Denmark. Schleswig became a Danish duchy in the 12th century and remained a fief associated with Denmark until it was forcibly annexed by Prussia and incorporated with Holstein as a single Prussian province in 1866. Following World War I the Danish majority living in North Schleswig (north of Flensburg) voted for incorporation with Denmark in a plebiscite (1920) held in accordance with the Treaty of Versailles
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