“ In the controversy arising out of the Schleswig-Holstein Question, which culminated in the war of Austria and Prussia against Denmark in 1864, the Eider gave its name to the “Eider Danes,” the intransigeant Danish party which maintained that Schleswig (Sønderjylland, South Jutland) was by nature and historical tradition an integral part of Denmark. The Eider Canal (Eider-Kanal) , which was constructed between 1777 and 1784, leaves the Eider at the point where the river turns to the west and enters the Bay of Kiel at Holtenau. ”