The medieval history of Southern Jutland (Danish: Sønder Jylland) is
   complicated, and the Nationalistic fuss of the 19th century produced
   some extra confusion. Both pro-Germans and pro-Danes used the history
   to prove that the Duchy of Slesvig rightfully ought to be a part of
   Germany - or Denmark - respectively.
   
   Jutland is a long peninsula. From the old Sagas we get the impression
   that Jutland "always" has been divided in a northern and a southern
   part at the Kongeå River.
   
   However, if archeology and Roman sources are balanced, one can assume
   that the Jutish people inhabited both the Kongeå region and the more
   northern part of the peninsula, while the Anglians lived approximately
   where the towns Haithabu and Schleswig later would emerge. The pattern
   of populated and unpopulated areas was relatively constant through
   Bronze Age and Iron Age.
   
   After a lot of Anglians had emigrated to the British Islands in the
   5th century, the land of the Anglians came in closer contact with the
   Danish islands - plausibly by immigration/occupation by the Danes.
   Later also the contacts increased between the Danes and the people on
   the northern half of the Jutish peninsula.
   
   As Charlemagne extended his realm in the late 8th century, he met a
   united Danish army which successfully defended Danevirke. A border was
   established at the River Eider A.D. 811.
   
   Danevirke was erected immediately south for the road where boats or
   goods had to be hauled for approximately 5 kilometers between a bay of
   the Baltic Sea and a small river (Rheider Au / Reider Å) connected to
   the North Sea. There, on the narrowest part of southern Jutland, an
   important transit market (Haithabu /Hedeby close to the later town
   Slesvig) was established, and protected by the fortification
   Danevirke.
   
   During the 9th century the border was adjusted to the south, and
   during a period Hamburg was occupied by Danes.
   
   This strength was enabled by three factors:
     * the fishing,
     * the good soil giving good pasture and harvests, and
     * in particular the tax and customes revenues from the market in
       Haithabu, where all trade between the Baltic Sea and Western
       Europe passed.
       
   The wealth of southern Jutland and the taxes from the Haithabu market
   was, of course, enticing. A separate kingdom of Haithabu /Hedeby was
   established around year 900 A.D. by the Viking chieftain Olaf from
   Svealand. Olaf's son and successor Gnupa was however killed in battle
   agains the Danish king, and his kingdom vanished.
   
   The southern border was then adjusted back and forth a few times. For
   instance the German Emperor Otto II did occupy land north of the River
   Eider in the years 974-983, stimulating German colonialization.
   
   Later Haithabu /Hedeby was burned by Swedes, and first under the reign
   of King Svend Forkbeard (986-1014) the situation was stabilized,
   although raids against Haithabu would be repeated. Again in 1066
   Haithabu was destroyed by fire.
   
   Knud Lavard (killed 1131) was called Duke of Jutland, and during the
   rule of his dynasty Southern Jutland functioned as the Duchy which
   provided for the expences of Royal Princes, which led to longlasting
   feuds between the Dukes and the Kings 1253-1325.
   
   Knud Lavard had inherited also parts of Holstein, and thereby come in
   conflict with Count Adolf in the German part of Holstein, as they both
   were very keen on expanding their influence and pacifying the Wagrian
   tribe. Count Adolf succeeded and established the County of Holstein
   (1143) with about the borders it has had since then. Holstein was
   Christianized, lots of the Wagrians were killed and the land was
   inhabited by settlers from Westphalia, Friesland and Holland. Soon the
   towns of Holstein, as Lübeck and Hamburg, became serious trade
   competitors on the Baltic Sea. Denmark tried her best to expand her
   influence to Holstein too, and during 1203-1227 the Count of Holstein
   acknoledged the King of Denmark as feudal lord.
   
   The wars between the kings of Denmark and the dukes of Slesvig were
   expensive, and Denmark had to finance them through extensive loans.
   The Dukes were usually allied with the Counts of Holstein, who
   happened to be the main creditors of the Danish Crown, too. In 1326,
   after a war between Denmark and Holstein, the underage Duke of Jutland
   was made king of Denmark, and his guardian Count Gerhard of Holstein
   was entfeofed with the Duchy as an inheritable fief.
   
   This was the time when almost all of Denmark came under the supremacy
   of the Counts of Holstein, who possessed different parts of Denmark as
   pawns for their credits. King Valdemar VI (Atterdag) started to regain
   the kingdom part by part. King Valdemar's son Henrik was in 1364
   nominally entfeofed with the Duchy, although he never reached to
   regain more than the northernmost parts as he couldn't raise the
   neccessary founds to repay the loans.
   
   As both Duke Henrik and King Valdemar died (1374 & 1375) the Duchy was
   the only important part of Denmark which still was controlled by the
   Counts of Holstein, who now declared the Duchy to be independent of
   the Danish Crown.
   
   Queen Margrete managed however in 1386 to reach an agreement with the
   creditors, who acknowledged the Danish Queen as feudal lord. The Duchy
   of Slesvig was thereby again a part of the Danish realm - nominally -
   but it took another 54 years of feuds until the Duchy in practice
   contributed with troops or taxes.
   
   In 1448 the Duke of Slesvig was influential enough to get his nephew
   Count Christiern elected King of Denmark, and when the Duke had died
   King Christiern was appointed Duke of Slesvig and Count of Holstein in
   1460. It followed a period of a hundred years when the Duchy many
   times was devided between inheritors.
   
   From the end of the 16th century the Duchy was split in only two
   parts: one held by the King of Denmark, and the other held by the Duke
   of Slesvig.
   
   During the 30-years War the relations between the Duke and the King
   worsened. Finally in 1658, after the Danes had invaded Swedish
   territories south of Hamburg, the Duke cooperated with the Swedes in
   their counter-attack which almost eradicated the Danish Kingdom. The
   peace treaty stipulated that the Duke no longer was a vassal of the
   Danish Crown.
   
   As Sweden in 1721 had lost its strength, Denmark could again
   incorporate the Duchy in the Danish realm, and the prior royal and
   ducal regions of the Duchy were united. The prior Duke remained Duke
   of Holstein under the German Emperor until 1773 when (almost) all of
   Holstein was gained by the King of Denmark (in his role as German Duke
   of Holstein).
   
   German had been the governmental language during the times of more or
   less independent Dukes, and remained so. Since the Reformation, German
   had also been dominating in Church and schools, while Danish was the
   dominating language among the peasantry.
   
   After the Napoleonic wars most of Europe experienced a national
   awakening. Not the least in the German speaking parts of Europe, as
   for instance in Slesvig and Holstein. 1806-1815 the government of
   Denmark had claimed Slesvig and Holstein to be parts of Denmark, which
   wasn't popular among the Germans. The revolutions 1848 all over Europe
   led in Slesvig and Holstein to a failed separatist rebellion, and
   Nationalists in Denmark advocated danification of Slesvig (but not
   Holstein). In 1864 the Danish government saw a historical opportunity
   to achieve this, but instead Prussia and Austria attacked. After a
   short war Slesvig and Holstein was ceded - and from 1866 incorporated
   with Prussia.
   
   After Germany had lost the first World War it was possible for Denmark
   to support the Danish speaking peasantry in Slesvig in their national
   strive. A referendum was held, and Slesvig was split between Germany
   and Denmark along a line immediately north for the town Flensburg.
   
   500-800 Southern Jutland probably inhabited by Danes
   800-900  [INLINE]   Southern Jutland held by Danes
   900-936 Southern Jutland a kingdom of its own.
   The king was from Sweden.
   936-974  [INLINE]   Southern Jutland held by Danes
   974-983 The German Emperor established a small colony on southernmost
   Jutland
   986-~1140  [INLINE]   Danish Earls ("Jarl") defend the border.
   ~1140-1325 Royal Princes are supported by revenues from a Duchy
   comprising rather limited parts of Southern Jutland. The dukes strive
   for independence from the Danish Crown.
   1326-1375 Southern Jutland ruled by the creditors, the Conts of
   Holstein
   1376-1386 The Duchy of Slesvig is claimed independent.
   1386-1440 The Duchy is in theory a part of the Danish realm, however
   mostly in war with the King of Denmark.
   1440-1460  [INLINE]   The Dynasty to which the Duke of Slesvig belongs
   increases their influence in the Danish realm. The Duchy is in
   practice a part of the Danish realm.
   1460-~1658 Holstein and Slesvig twin-duchies with peculiar rules for
   succession. All, or parts, of the Duchies held by the King of Denmark.
   Other parts by brothers and cousins. The dukes strive for independence
   from the Danish Crown.
   1658-1721 Half of the Duchies Slesvig and Holstein ruled by a
   sovereign Duke, the other half ruled by the King of Denmark.
   1721-1773  [INLINE]   All of the Duchy of Slesvig and the half of
   Holstein ruled by the King of Denmark.
   1773-1864  [INLINE]   All of the Duchy of Slesvig and all of Holstein
   ruled by the King of Denmark.
   1864-1920 All of the Duchy of Slesvig and all of Holstein incorporated
   in the German Imperium.
   1920-- The northernmost part of the Duchy of Slesvig (Sønderjylland)
   is re-united with Denmark
   

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