The Treaty of Heiligen was signed in 811 between the

Danish Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish a ...

King Hemming and

Charlemagne Charlemagne ( , ) or Charles the Great ( la, Carolus Magnus; german: Karl der Große; 2 April 747 – 28 January 814), a member of the Carolingian dynasty, was King of the Franks from 768, King of the Lombards from 774, and the first Holy ...

. Based on the terms of the accord, the southern boundary of Denmark was established at the

Eider River The Eider (german: Die Eider; da, Ejderen; Latin: ''Egdor'' or ''Eidora'') is the longest river in the German state of Schleswig-Holstein. The river starts near Bordesholm and reaches the southwestern outskirts of Kiel on the shores of the Balt ...

. Moreover, the treaty confirmed the peace established by both signatories in 810.Thursten, p. 67. Since the days of King

Offa Offa (died 29 July 796 AD) was King of Mercia, a kingdom of Anglo-Saxon England, from 757 until his death. The son of Thingfrith and a descendant of Eowa, Offa came to the throne after a period of civil war following the assassination of Æt ...

the Eider river had been the border between the settlement area of the

Angles The Angles ( ang, Ængle, ; la, Angli) were one of the main Germanic peoples who settled in Great Britain in the post-Roman period. They founded several kingdoms of the Heptarchy in Anglo-Saxon England. Their name is the root of the name ' ...

and

Saxons The Saxons ( la, Saxones, german: Sachsen, ang, Seaxan, osx, Sahson, nds, Sassen, nl, Saksen) were a group of Germanic * * * * peoples whose name was given in the early Middle Ages to a large country (Old Saxony, la, Saxonia) near the Nor ...

. After Charlemagne had subjected the

Duchy of Saxony The Duchy of Saxony ( nds, Hartogdom Sassen, german: Herzogtum Sachsen) was originally the area settled by the Saxons in the late Early Middle Ages, when they were subdued by Charlemagne during the Saxon Wars from 772 and incorporated into the C ...

to his rule, Hemming's predecessor and uncle

Gudfred Gudfred was a ninth century Danish king who reigned from at least 804 to 810. Alternate spellings include ''Godfred'' (Danish), ''Göttrick'' (German), ''Gøtrik'' (Danish), ''Gudrød'' (Danish), and ''Godofredus'' (Latin). He stands at the thres ...

took the chance, crossed the Eider and campaigned in the southern lands, which Charles had left to the allied

Obotrite The Obotrites ( la, Obotriti, Abodritorum, Abodritos…) or Obodrites, also spelled Abodrites (german: Abodriten), were a confederation of medieval West Slavic tribes within the territory of modern Mecklenburg and Holstein in northern Germany ( ...

s. The king however was killed by his retinue in 810 and Hemming, to assure his rule against his rivaling cousins, sought peace with the

Franks The Franks ( la, Franci or ) were a group of Germanic peoples whose name was first mentioned in 3rd-century Roman sources, and associated with tribes between the Lower Rhine and the Ems River, on the edge of the Roman Empire.H. Schutz: Tools, ...

. His and the Emperor's negotiators met on an island of the Eider in present-day

Rendsburg Rendsburg ( da, Rendsborg, also ''Rensborg'', nds, Rendsborg, also ''Rensborg'') is a town on the River Eider and the Kiel Canal in the central part of Schleswig-Holstein, Germany. It is the capital of the ''Kreis'' (district) of Rendsburg-Ecke ...

and defined the limits of their spheres of influence. Though in the following decades several quarrels occurred in the border area and the German King

Henry I Henry I may refer to: 876–1366 * Henry I the Fowler, King of Germany (876–936) * Henry I, Duke of Bavaria (died 955) * Henry I of Austria, Margrave of Austria (died 1018) * Henry I of France (1008–1060) * Henry I the Long, Margrave of the No ...

conquered Danish

Hedeby Hedeby (, Old Norse ''Heiðabýr'', German language, German ''Haithabu'') was an important Danes, Danish Viking Age (8th to the 11th centuries) trading settlement near the southern end of the Jutland Peninsula, now in the Schleswig-Flensburg dist ...

at the

Danevirke The Danevirke or Danework (modern Danish spelling: ''Dannevirke''; in Old Norse; ''Danavirki'', in German; ''Danewerk'', literally meaning '' earthwork of the Danes'') is a system of Danish fortifications in Schleswig-Holstein, Germany. This his ...

in 934, the border was confirmed by

Canute the Great Cnut (; ang, Cnut cyning; non, Knútr inn ríki ; or , no, Knut den mektige, sv, Knut den Store. died 12 November 1035), also known as Cnut the Great and Canute, was King of England from 1016, King of Denmark from 1018, and King of Norway ...

and King

Conrad II Conrad II ( – 4 June 1039), also known as and , was the emperor of the Holy Roman Empire from 1027 until his death in 1039. The first of a succession of four Salian emperors, who reigned for one century until 1125, Conrad ruled the kingdoms ...

in 1025 at the betrothal of their children

Gunhilda Gunhild (with variants Gundhild, Gunhilda, Gunhilde, Gunhjild, Gunilda, Gunnhild, Gunnhildr, Gunnhildur) is a Germanic feminine given name composed of two words meaning "war" (gunn and hild/hildr). It may refer to: *, allegedly a Danish queen cons ...

and Henry III. For centuries the Eider marked the border between the Danish

Duchy of Schleswig The Duchy of Schleswig ( da, Hertugdømmet Slesvig; german: Herzogtum Schleswig; nds, Hartogdom Sleswig; frr, Härtochduum Slaswik) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km ( ...

and the German

County of Holstein Holstein (; nds, label=Northern Low Saxon, Holsteen; da, Holsten; Latin and historical en, Holsatia, italic=yes) is the region between the rivers Elbe and Eider. It is the southern half of Schleswig-Holstein, the northernmost state of German ...

, but these came to be united under one ruler and proclaimed indivisible, which caused the Eider boundary to become

disputed Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin ''controversia'', as a composite of ''controversus'' – "turned in an opposite d ...

in the 19th century. This dispute was finally settled after World War I: The Danish-German border which had been moved north to the

Kongeå The Kongeå (in German ''Königs Au'') is a watercourse in Southern Jutland in Jutland, Denmark. It rises southeast of Vejen and Vamdrup and after about it flows through a sluice to tidal mudflats and sandbanks north of Ribe, and eventually into ...

after the Prussian-Austrian conquest in 1864 was relocated south to its present location between Kongeå and Eider. The southern, German part of Schleswig was by then mostly German-speaking and identifying as German and remained part of the

Province of Schleswig-Holstein The Province of Schleswig-Holstein (german: Provinz Schleswig-Holstein ) was a province of the Kingdom of Prussia (subsequently the Free State of Prussia after 1918) from 1868 to 1946. History It was created from the Duchies of Schleswig and H ...

References

Sources

External links

*
History of Denmark
Heiligen Heiligen 9th century in Europe Heiligen Charlemagne 811 Military history of the Carolingian Empire History of Schleswig-Holstein {{Germany-hist-stub