Editing Schleswig-Holstein (section)

==History==
{{main|History of Schleswig-Holstein}}
{{More citations needed section|date=July 2024}}
[[File:AreasSettlementSchleswig-HolsteinText.png|thumb|The historic settlement areas in present-day Schleswig-Holstein]]
The term "Holstein" derives from [[Old Saxon]] ''Holseta Land,'' (''Holz'' means wood in modern Standardized German; ''[[Woodland|holt]]'' is a now-archaic English word for woods.) Originally, the term referred to the central of the three [[Saxons|Saxon]] tribes north of the [[River Elbe]]: ''Tedmarsgoi'' ([[Dithmarschen (gau)|Dithmarschen]]), [[Holstein]] and ''Sturmarii'' ([[Stormarn (gau)|Stormarn]]). The area inhabited by the tribe of the Holsts lay between the [[Stör]] River and [[Hamburg]]; after [[Christianization]], their main church was in [[Schenefeld, Steinburg|Schenefeld]]. [[Duchy of Saxony|Saxon]] Holstein became a part of the [[Holy Roman Empire]] after [[Charlemagne]]'s [[Saxon Wars|Saxon campaigns]] in the late eighth century. Beginning in 811, the northern border of Holstein (and thus of the Empire) was the [[Eider (river)|River Eider]].{{Citation needed|date=June 2024}}

The term "Schleswig" originally referred to the city of [[Schleswig, Schleswig-Holstein|Schleswig]]. The word Schleswig is a German transliteration of the Danish word Slesvig, which consists of two words: [[Schlei]] and vig. The Schlei refers to the river at which the city lies, and vig means "[[inlet]]" or bay. Schleswig therefore means (in Danish): "The bay at the river Schlei".
The Schlei is known as Slien in Danish and is believed to have been used only for the inner Slien (the Great and Little Bay near the city of Schleswig). The word is thought to be related to Slæ, which means reeds and aquatic plants found in this area.{{Citation needed|date=June 2024}}

The [[Duchy of Schleswig]], or Southern Jutland, was originally an integral part of Denmark, but in [[medieval]] times was established as a [[fief]] under the control of the Kingdom of Denmark, having the same relationship with the [[Danish Royal Family|Danish Crown]] as, for example, [[Brandenburg]] or [[Bavaria]] had with the [[Holy Roman Emperor]]. Around 1100, the [[Duchy of Saxony]] gave Holstein to [[Count]] [[Adolf I of Holstein|Adolf I]] of [[County of Schauenburg|Schauenburg]].{{Citation needed|date=June 2024}}

===The Migration Period===
[[File:Danevirke 123.jpg|thumb|The [[Danevirke]], stretching from the [[Treene (river)|Treene River]] in the east to [[Schlei|Schlei Bay]] in the west.]]
[[File:Hærvejen.gif|thumb|upright=0.75|The [[Hærvejen]], starting at its northern terminus in [[Viborg, Denmark|Viborg]] and reaching its southern terminus in [[Hamburg]].]]
During the [[Migration Period]], the [[Jutland]] peninsula was home to several tribes. The [[Jutes]] inhabitted the most northern part of the peninsula from [[Grenen]] to {{ill|Olger's Dyke|de|Olgerdige}}. This dyke, dating back to around the first century, served as the boundary between the Jutes in the north and the [[Angles (tribe)|Angles]] in the south.<ref>{{cite web |title=Olgerdiget: Den første grænse |url=https://politikenhistorie.dk/art7619917/Den-f%C3%B8rste-gr%C3%A6nse |website=Politikenhistorie |access-date=28 September 2024 |language=da-DK |date=5 February 2020}}</ref> This dyke lost its relevance in the 200s when the Angles expanded northward, leading to the establishment of a new dyke called the {{ill|Wendish Dyke|da|Vendersvold Vendersvold (Wendish dyke)}}. The southern border of the Angles was marked by the [[Marsh|marshes]] surrounding the [[Eider (river)|Eider]], that combined with the dense [[Old-growth forest|old-growth forrest]] to the south of the river, formed a natural barrier.<ref>{{cite web |title=Eider River {{!}} North Sea, Schleswig-Holstein, Denmark {{!}} Britannica |url=https://www.britannica.com/place/Eider-River |website=www.britannica.com |language=en}}</ref> South of the forest lay the region now known as Holstein, which was divided between the [[Germanic peoples|Germanic]] [[Saxons]], who inhabited the western part, and the [[Slavs|Slavic]] [[Wagria|Wagri]], who lived in the eastern part. In the 8th century, the Wagri would become part of the Slavic tribal confederation known as the [[Obotrites]].<ref>{{cite web |title=Obodrite {{!}} Germanic Tribe, Slavic Tribe, Paganism {{!}} Britannica |url=https://www.britannica.com/topic/Obodrite |website=www.britannica.com |language=en}}</ref> (Also known as the [[Wends]] by the Danes and Saxons).<ref>{{cite web |title=Wend {{!}} Germanic tribe, Migration, Paganism {{!}} Britannica |url=https://www.britannica.com/topic/Wend |website=www.britannica.com |language=en}}</ref>

During the 4th and early 5th centuries, a significant migration saw the Jutes, Angles, and Saxons depart from their homelands to settle in the [[British Isles]].<ref>Jim Storr, The Anglo-Saxon Conquest of England. Helion & Company, Warwick, 2023.</ref> This mass exodus left much of the Jutland Peninsula sparsely populated, allowing the Danes from southern Scandinavia and the islands of [[Zealand]], [[Funen]], and other smaller Danish isles to migrate into the peninsula. They gradually settled the region, integrating the remaining Jutes and Angles who had not left for Britain. By the mid 5th century, the Danes had established settlements from Grenen in the north to just north of the Eider River and its marshes. Their southernmost settlements being around [[Schwansen]], [[Hedeby]] and [[Husum]], mirroring the same southern border as their Angle predecessors.<ref>{{cite web |title=Grænselandets historie |url=https://graenseforeningen.dk/om-graenselandet/graenselandets-historie |access-date=28 September 2024 |website=Graenseforeningen |language=da}}</ref> As raiding was a frequent practice among the Danes, Saxons, and Wagrians, the borderlands was a hostile and unsafe area to inhabit. In response to these threats, the Danes began constructing the [[Danevirke]]. Originally built as a dyke, it was gradually expanded into a 30-kilometer earthwork with a palisade fortification, forming a barrier between the Danes and their southern neighbors. The Danevirke was strategically positioned  at the most narrow point of the peninsula, with its eastern end beginning at the [[Treene (river)|Treene River]] and extending to the [[Schlei |Schlei Bay]].<ref>Henrik Jansen, Danevirke. Aarhus University Press, Aarhus, 2013.</ref> This fortification served to deter Saxon and Wagrian raids while enabling the Danes to launch their own raids into southern territories. It would remain in use until 1864, being expanded and adapted to the changing military needs of the Danes multiple times.<ref>{{cite web |title=Dannevirke, 500- |url=https://danmarkshistorien.dk/vis/materiale/dannevirke |website=danmarkshistorien.dk |date=24 March 2025 |language=da}}</ref>

The establishment of the Danevirke not only helped to prevent Saxon and Wagrian raids into Danish territory but also served as a toll station. Danish chieftains would collect fees from traders, merchants, and peasants traveling along the [[Hærvejen]] (Heerweg/Armyway), the main trade route running through the peninsula. Saxons, Wagrians, and Danes alike used the Hærvejen to trade goods such as honey, furs, amber, glass, metalwork, and other commodities, such as livestock, with cattle and oxen being particularly important. Especially the Danes developed a thriving livestock breeding industry, driving large herds along the Hærvejen to sell on the continent. This trade gave the route its alternative names, such as "Studevejen" (Cattle Way) in Danish and "Ochsenweg" (Oxen Way) in German.<ref>{{cite web |title=Ochsenweg – Gesellschaft für Schleswig-Holsteinische Geschichte |url=https://geschichte-s-h.de/sh-von-a-bis-z/o/ochsenweg/ |website=geschichte-s-h.de |access-date=28 September 2024}}</ref> Therefore control of the Danevirke, through which the Hærvejen ran, was of immense financial significance. Whoever controlled the gates of Danevirke also controlled the trade along the Hærvejen, giving them access to substantial wealth.

===The Early Middle Ages===
After approximately 350 to 400 years of Danes being the sole inhabitants north of the Eider, the [[Frisians]] arrived in two waves, the first of which occurred in the 800s. They came from [[Frisia]] and initially settled on the islands of [[Heligoland]], [[Sylt]], [[Föhr]] and [[Amrum]] in the southwestern part of Jutland. Later, they expanded to [[Eiderstedt]] and the Jutish coastline.<ref>Nelleke IJssennagger and John Hines (eds.), Frisians and Their North Sea Neighbours: From the Fifth Century to the Viking Age. Boydell Press, Woodbridge, 2017.</ref> These areas eventually became known as [[North Frisia]], though historically, the region was referred to as [[Uthlande]] (Outland).<ref>John Hines and Nelleke IJssennagger-van der Pluijm (eds.), Frisians of the Early Middle Ages: Studies in Historical Archaeoethnology. Boydell Press, Woodbridge, 2020.</ref> In these settlements, the Frisians established fishing and trading stations. The local Danes soon became a minority and, over time, assimilated into the Frisian population.<ref>{{cite journal |last=Århammar |first=Nils |date=1992 |title=Om danske låneord i nordfrisisk og deres betydning for jysk ord- og lydhistorie med en ekskurs om nordfrisiske lån i jysk |url=http://www.hum.au.dk/jysk/publikationer/ordsag12.pdf |journal=Ord & Sag |language=da |publisher=Institut for Jysk Sprog-og Kulturforskning, [[Aarhus University]] |volume=12 |doi=10.7146/ordogsag.v12.149553 |issn=0108-8025 |archive-url=https://web.archive.org/web/20070609160706/http://www.hum.au.dk/jysk/publikationer/ordsag12.pdf |archive-date=9 June 2007 |access-date=28 September 2024}}</ref> The Frisians contributed to the broader Hærvejen trade network, with sea routes extending along the Frisian and Dutch coasts, supplying high-quality salt, fish, and other maritime goods. Moreover, they were particularly active in trade with [[East Anglia]] in [[England]], where pottery was exchanged in large quantities.{{cn|date=September 2024}}

====Saxon Wars====
[[File:Limes.saxoniae.wmt.png|thumb|The {{Lang|la|[[Limes Saxoniae]]}} border between the [[Saxons]] and the [[Obotrites]], established about 810 in present-day Schleswig-Holstein]]
{{main|Saxon Wars}}
Normalcy in the area vanished with the expansion of the [[Francia|Frankish Empire]] into [[Saxons|Saxony]] from 772 to 804, triggering a generational war on an unprecedented scale for the region. Prior to this, the Franks had spent nearly 20 years, from the late 600s to the early 700s, subjugating and converting the [[Frisian Kingdom]]. Their primary opponent was the formidable Frisian king [[Radbod of Frisia|Redbad]], who fiercely resisted the Franks until his death. Now, the Frisians' neighbors, the Saxons, faced Frankish expansion. The ''casus belli'' was a Saxon raid on the church in [[Deventer]] in January of 772. This conflict, fueled by [[Charlemagne]]'s desire to conquer the Saxons and convert them from their belief in the [[Germanic mythology|Germanic pantheon]] to [[Christianity]], used the Deventer raid as a pretext to wage a war that would ultimately reshape the political and cultural landscape of what would later become Holstein forever. Over the course of 18 campaigns, carried out in three phases over 32 years, Charlemagne aimed to subdue the Saxons and forcibly convert them to Christianity, in what became known as the [[Saxon Wars]].{{cn|date=September 2024}} In retaliation for the raid on the church in Deventer, Charlemagne ordered his troops to destroy the holy pillar [[Irminsul]], near [[Paderborn]] in either 772 or 773—a notorious act that sent shockwaves throughout the Germanic pagan world.{{cn|date=September 2024}} It has been postulated that Irminsul symbolised [[Yggdrasil|Yggdrasil Ash]] - the world tree. Charlemagne then destroyed all Saxon settlements up to the [[Weser|Wesser]] river. After defeating the Saxons and securing [[Hostage diplomacy|hostages]], he turned his attention to northern [[Italy]].{{cn|date=September 2024}} 

For centuries, the Danes and Saxons had regarded each other as kindred peoples, sharing the same belief in the Germanic pantheon and frequently intermarrying, especially among the elite.{{cn|date=September 2024}} Thus, the defeated Saxon warleader [[Widukind]] sought refuge with his father-in-law, Danish king [[Sigfred]]. The ''[[Royal Frankish Annals]]'' mention that Widukind received substantial aid from Sigfred, though the exact nature of this aid is not explicitly stated. However, the chronicles do note that Sigfred and Charlemagne brokered a peace agreement some years later, indicating that Sigfred, upon hearing Widukind's plea, may have mustered his army and joined the war on the side of the Saxons.{{cn|date=September 2024}} In response to the Danes' involvement in the war, Charlemagne seems to have recruited the [[Obotrites]] by promising them the Saxon portion of Holstein.{{cn|date=September 2024}} This alliance with Charlemagne shifted the balance of power in the region. In 782, after another defeat of the Saxons, Charlemagne ordered the mass execution of 4,500 Saxons, an atrocity that became known as the [[Massacre of Verden]]. Following this brutal act, Charlemagne was nicknamed the "Butcher of Saxons" or "Saxonslaughterer."{{cn|date=September 2024}}

In 796, despite Saxony being fully under Frankish rule, the Saxons rose up once more, supported by the Danes. The rebellion was triggered by forced conscription of Saxons for the Frankish [[Avar Wars|wars against the Avars]]. Moreover, Charlemagne, in alliance with the Obotrites, planned to subjugate the Danes, now led by King [[Gudfred|Gudfred Sigfredson]].{{cn|date=September 2024}} However, Gudfred struck first. He expanded the Danevirke, assembled a fleet, mustered an army, and launched attacks on the Obotrites and later Frankish Frisia. But he was slain, either by one of his [[huscarls]] or possibly his own illegitimate son, on the Frisian campaign. The new Danish king, [[Hemming of Denmark|Hemming]], Gudfred's nephew, initiated peace talks, which resulted in the [[Treaty of Heiligen]] in 810. The treaty established the Danish border at the Eider River. Charlemagne retained Saxony, including Holstein, and established the [[Limes Saxoniae]] as a border with the Obotrites. This agreement established firm boundaries between the Franks, Obotrites, and Danes, securing peace in the region.{{cn|date=September 2024}}

===Duchies in the Danish realm===
Between 500 and 1200, Schleswig was an integral part of Denmark, but during the 12th century, [[Abel, King of Denmark|Duke Abel of Schlewig]] came into conflict with his brother [[Eric IV of Denmark|King Eric IV]]. Abel managed to gain autonomy from his brother, making Schleswig an autonomous duchy. Later, Abel had Eric assassinated and seized the throne. Despite this, Schleswig remained an autonomous duchy within the Kingdom, setting the stage for future conflicts.{{cn|date=September 2024}}
Beginning in 1460, both the [[Duchy of Schleswig]] and [[Duchy of Holstein]], were ruled together by the Danish king, who acted as the duke of both regions. Holstein being a duchy within the [[Holy Roman Empire]] created a situation where the Danish king was sovereign of Denmark but also a duke within the Holy Roman Empire. Both were ruled for several centuries by the kings of Denmark. In 1721, all of Schleswig was united into a single duchy under the king of Denmark, and the great powers of Europe confirmed in an international treaty that all future kings of Denmark should automatically become dukes of Schleswig: consequently, Schleswig would always follow the order of succession that applied in the Kingdom of Denmark.{{Citation needed|date=June 2024}} 

Following the Protestant Reformation, German was established as the language of commerce, administration, education, and clergy in Schleswig despite the population being ethnically Danish. This was because Schleswig were managed by the German Chancellery, in Kiel, which was later renamed the Schleswig-Holstein Chancellery in 1806. Therefore, Danes were sent to Kiel for their education instead of Copenhagen, where they received their education in German rather than their native Danish. As a result, Danish students, future administrators, clergy, and educators were taught in German and continued to use the language throughout their professional lives.{{Citation needed|date=June 2024}}

In 1814, mandatory schooling was instituted, and was taught in German. This created generations of Danish children who learned German from an early age. Their schooling was conducted in German, they heard sermons in German, and when they grew up, their interactions with the administration and business were conducted in German. Additionally, if Danes didn't learn German, they couldn't communicate with the administration, which often cared little if the citizens were able to understand them. Therefore, if the Danes weren't able to speak German, they were effectively frozen out of any official matters. As a result, a language shift slowly began forming in South Schleswig and gradually spread north, which alarmed Copenhagen. The Danish authorities started taking countermeasures to halt the language shift by banning German in all official matters in Schleswig, which only served to create tensions between Danes and Germans. This language strife significantly contributed to shaping the inhabitants' national sentiments during a time of national unrest in Europe. It is also during this period that we see surname changes, such as from Jørgensen to Jürgensen or Nielsen to Nilsen, in South Schleswig.
By the time of the First Schleswig War, one-third of Schleswig and half of South Schleswig spoke German as their first language. By the time of the Second Schleswig War in 1864, half of Schleswig and the vast majority of South Schleswig spoke German as their first language.{{Citation needed|date=June 2024}}

===Schleswig-Holstein Question===
{{main|Schleswig–Holstein question}}
In the 19th century, fueled by  [[nationalism]] both Danes and Germans claimed Schleswig-Holstein. The Germans wanted both Schleswig and Holstein to separate from Denmark and join the [[German Confederation]], invoking the [[Treaty of Ribe]] stating that the two duchies should stay "Forever Undivided". The Danes on the other hand, furthered the Eider Policy ([[:da:Ejderpolitikken]]), stating that the natural Danish border was the [[Eider (river)]] as first recognised in the [[Treaty of Heiligen]]. Therefore, the Danes sought to reintegrate Schleswig into the [[Danish Realm|Kingdom of Denmark]], reversing the separation created by King Abel, while also granting Holstein independence to join the German Confederation as a sovereign entity. The resulting long-term political and territorial dispute was known as the [[Schleswig–Holstein question|Schleswig-Holstein Question]]. Holstein was entirely German-speaking, while Schleswig was predominantly Danish-speaking until the late 1700 and early 1800s. During this period, a linguistic shift began in southern Schleswig, transitioning from Danish to German. This meant that Schleswig was linguistically divided with a Danish-speaking north and a German-speaking south.{{cn|date=September 2024}}

In 1848, King [[Frederick VII of Denmark]] declared that he would grant Denmark a liberal constitution and the immediate goal of the Danish national movement was to ensure that this constitution would give rights to all Danes, i.e. not only to those in the Kingdom of Denmark, but also to Danes (and Germans) living in Schleswig. Furthermore, they demanded protection for the Danish language in Schleswig (the dominant language in almost a quarter of Schleswig had changed from Danish to German since the beginning of the 19th century).{{Citation needed|date=June 2024}} A liberal constitution for Holstein was not seriously considered in [[Copenhagen]], since it was well known that the political élite of Holstein were more conservative than Copenhagen's. Representatives of German-minded Schleswig-Holsteiners demanded that Schleswig and Holstein be unified and allowed its own constitution and that Schleswig join Holstein as a member of the [[German Confederation]].{{cn|date=September 2024}} These demands were rejected by the Danish government in 1848, and the Germans of Holstein and Southern Schleswig rebelled. 

====First Schleswig War====
This began the [[First Schleswig War]] (1848–51). Against unbelievable odds, Denmark emerged victorious, managing to politically outmaneuver the German alliance by garnering support from the [[British Empire]], the [[Russian Empire]] and the [[Second French Empire]] while defeating the Germans at the [[Battle of Bov|Battles of Bov]], the [[Battle of Dybbøl (1848)|Dybbøl]], the [[Battle of Fredericia|Fredericia]] and [[Battle of Isted|Isted]]. However, under pressure from the [[Great Power]]s, led by [[Alexander III of Russia|Tsar Alexander III]], who had forced [[Kingdom of Prussia|Prussia]] and [[Austrian Empire|Austria]] out of Denmark,{{cn|date=September 2024}} the Danes were not permitted to reintegrate Schleswig into Denmark. Alexander thereby sought to preserve the existing European order,in accordance with the principles established by the [[Concert of Europe]]. This led to the signing of the [[London Protocol (1852)|1852 London Protocol]], which failed to provide a solution to the issue and merely upheld the status quo.{{cn|date=September 2024}} 

====Second Schleswig War====
In 1863, conflict broke out again when Frederick VII died without legitimate issue. According to the [[order of succession]] of Denmark and Schleswig, the crowns of both Denmark and Schleswig would pass to Duke Christian of [[House of Glücksburg|Glücksburg]], who became [[Christian IX of Denmark|Christian IX]]. The transmission of the duchy of Holstein to the head of the (German-oriented) branch of the Danish royal family, the [[House of Schleswig-Holstein-Sonderburg-Augustenburg|House of Augustenborg]], was more controversial. The separation of the two duchies was challenged by the Augustenborg heir, who claimed, as in 1848, to be rightful heir of both Schleswig and Holstein. A common constitution for Denmark and Schleswig was promulgated in November 1863, which was a breach of the 1852 London Protocol. This left Denmark politically isolated and led to the [[Second Schleswig War]], with Prussia and Austria invading once again. This was the [[Second War of Schleswig]]. Denmark achieved some initial victories at the [[Battle of Mysunde (1864)|Battles of Mysunde]], and [[Battle of Sankelmark|Sankelmark]], but these successes were short-lived. The Austrians defeated the Danes at the [[Battle for Königshügel|Königshügel]] and [[Battle of Vejle|Vejle]]. However, it was the Prussians who decided the war by decisively winning the pivotal [[Battle of Dybbøl|Battles of Dybbøl]] and [[Battle of Als|Als]].{{cn|date=September 2024}} 

British attempts to mediate in the [[London Conference of 1864]] failed. With the peace [[Treaty of Vienna (1864)]], Denmark was forced to cede Schleswig, Holstein and [[Saxe-Lauenburg|Lauenburg]] to Prussia and Austria. Prussia wished to annex the conquered territories but Austria insisted they be held as [[condominium]]s. This disagreement led to the 1865 [[Gastein Convention]], which, despite their {{lang|la|[[casus belli]]}} being the defence of the German-speaking Schleswig-Holsteiners' wish to remain unified, granted Schleswig and Lauenburg to Prussia and Holstein to Austria. However, this situation did not last long.

===Austro-Prussian War and Province of Prussia===
In 1866 the [[Austro-Prussian War]] broke out, in which Prussia quickly defeated Austria and its allies. In the 1866 [[Peace of Prague (1866)|Peace of Prague]] Prussia gained Holstein in addition to Schleswig and Lauenburg. Contrary to the hopes of German Schleswig-Holsteiners, the area did not gain its independence, but was annexed to Prussia, becoming the [[Province of Schleswig-Holstein]] in 1868; Lauenburg remained a separate entity until it was incorporated as {{lang|de|[[Kreis Herzogtum Lauenburg]]}} in 1876. 

The Peace of Prague also led to the dissolution of the loose ([[confederal]]) Austrian-led [[German Confederation]] and the establishment of the far more integrated ([[Federalism|federal]]) Prussian-led [[North German Confederation]], of which Schleswig-Holstein was now part as a Prussian Province; the North German Confederation became the [[German Empire]] in 1871.

Section five of the Peace of Prague had also stipulated that the people of Northern Schleswig would be consulted in a [[referendum]] on whether to remain under Prussian rule or return to Danish rule. This condition, however, was never fulfilled by Prussia. During the decades of Prussian rule within the [[German Empire]], authorities attempted a [[Germanisation]] policy in the northern part of Schleswig, which remained predominantly Danish. The period also meant increased industrialisation of Schleswig-Holstein and the use of Kiel and Flensburg as important [[Imperial German Navy]] locations. The northernmost part and west coast of the province saw a wave of emigration to America, while some Danes of North Schleswig emigrated to Denmark.{{Citation needed|date=June 2024}}

===Plebiscite in 1920===
[[File:Abstimmung-schleswig-1920.png|thumb|right|275px|Results of the 1920 plebiscites in North and Central Schleswig]]
{{main|1920 Schleswig plebiscites}}
Following the defeat of Germany in [[World War I]], the Allied powers arranged [[Schleswig Plebiscites|a plebiscite in northern and central Schleswig]]. The plebiscite was conducted under the auspices of an international commission which designated two voting zones to cover the northern and south-central parts of Schleswig. Steps were taken to also create a third zone covering a southern area, but zone III was cancelled again and never voted, as the Danish government asked the commission not to expand the plebiscite to this area.{{Citation needed|date=June 2024}}

In zone I covering Northern Schleswig (10 February 1920), 75% voted for [[Political union|reunification]] with Denmark and 25% voted for Germany. In zone II covering central Schleswig (14 March 1920), the results were reversed; 80% voted for Germany and just 20% for Denmark. Only minor areas on the island of [[Föhr]] showed a Danish majority, and the rest of the Danish vote was primarily in the town of Flensburg.<ref>Schwedler, Frank: Historischer Atlas Schleswig-Holstein 1867 bis 1945, Wachholtz Verlag, Neumünster</ref> On 15 June 1920, Northern Schleswig officially returned to Danish rule. The Danish/German border was the only one of the borders imposed on Germany by the [[Treaty of Versailles]] after World War I that was never challenged by [[Adolf Hitler]].

In 1937, the Nazis passed the so-called [[Greater Hamburg Act]] ({{lang|de|Groß-Hamburg-Gesetz}}), where the nearby Free and Hanseatic City of Hamburg was expanded, to encompass towns that had formerly belonged to the Prussian [[province of Schleswig-Holstein]]. To compensate Prussia for these losses (and partly because Hitler had a personal dislike for [[Lübeck]]<ref>{{cite web |url=http://www.telegraph.co.uk/travel/citybreaks/5428909/Lubeck-The-town-that-said-no-to-Hitler.html |title=Lübeck: The town that said no to Hitler |first=Simon |last=Heffer |date=2 June 2009 |newspaper=telegraph.co.uk |archive-url=https://web.archive.org/web/20090605161538/http://www.telegraph.co.uk/travel/citybreaks/5428909/Lubeck-The-town-that-said-no-to-Hitler.html |access-date=28 June 2010 |archive-date=5 June 2009 }}</ref>), the 711-year-long independence of the Hansestadt Lübeck came to an end, and almost all its territory was incorporated into Schleswig-Holstein, along with the [[Free State of Oldenburg|Oldenburg]] exclave centred on [[Eutin]] (for historical reasons known as {{lang|de|[[Principality of Lübeck|Landesteil Lübeck]]}}).

===State of Federal Germany===
After [[World War II]], the Prussian province Schleswig-Holstein came under [[British occupation zone in Germany|British occupation]]. On 23 August 1946, the military government abolished the province and reconstituted it as a separate ''Land''.<ref>Ordinance No. 46, {{cite web |url= http://www.lwl.org/westfaelische-geschichte/que/normal/que1167.pdf |title=''Abolition of the Provinces in the British Zone of the Former State of Prussia and Reconstitution thereof as Separate Länder'' |access-date= 23 August 2006 |archive-date=11 October 2006 |archive-url=https://web.archive.org/web/20061011113513/http://www.lwl.org/westfaelische-geschichte/que/normal/que1167.pdf |url-status=live }}&nbsp;{{small|(218&nbsp;KB)}}</ref>

On 9 September 1946, the British and Soviets offered Denmark South Schleswig, in the {{ill|Septembernote|de}}. In this note, they gave Denmark carte blanche on how to deal with the German-speaking South Schleswigers, whether to integrate them into the Danish state or to forcibly expel them from South Schleswig, as was [[Flight and expulsion of Germans (1944–1950)|being done to Germans in Eastern Europe]]. Denmark's then Prime Minister, [[Venstre (Denmark)|the Liberal Party's]] [[Knud Kristensen]], enthusiastically accepted the offer of South Schleswig reunification with Denmark. A survey showed that 75% of the Danish population supported the incorporation, 500,000 signatures had been collected in support of it and the Danish South Schleswig Association had sent the government a formal request for incorporation. However, the dominating [[Danish Social Liberal Party|Social Liberal Party]] feared that Denmark might again face destructive wars like the two Schleswig Wars once Germany recovered from World War II. Given that the Germans had conquered Denmark in six hours during the [[German invasion of Denmark (1940)|German invasion of Denmark]], they believed Denmark would not stand a chance in such a scenario. Therefore, they pressured the Prime Minister to call for [[1947 Danish Folketing election|new elections]], where the [[Venstre (Denmark)|Liberal Party]] did not secure enough votes to form a government. The [[Social Democrats (Denmark)|Social Democrats]] won the election with a minority government and could not gather a strong enough mandate for the incorporation of South Schleswig. This outcome created outrage within the Danish population and was considered a scandal.{{cn|date=September 2024}} 

Due to the [[Flight and expulsion of Germans (1944–1950)|forced migrations of Germans between 1944 and 1950]], Schleswig-Holstein [[Refugees in Schleswig-Holstein after the Second World War|took in almost a million refugees]] after the war, increasing its population by 33%.<ref>[http://www.hdg.de/lemo/html/Nachkriegsjahre/DasEndeAlsAnfang/fluchtUndVertreibung.html Flucht und Vertreibung] {{Webarchive|url=https://web.archive.org/web/20101228004729/http://www.hdg.de/lemo/html/Nachkriegsjahre/DasEndeAlsAnfang/fluchtUndVertreibung.html |date=28 December 2010 }} at [[Haus der Geschichte]] {{in lang|de}}</ref> 
[[File:DBP 1985 1241 Bonn-Kopenhagener Erklärungen.jpg|thumb|A German postage stamp conmemorating the Bonn-Copenhagen Declarations]]
A pro-Danish political movement arose in Schleswig, with transfer of the area to Denmark as an ultimate goal. This was supported neither by the British occupation administration nor the Danish government.{{cn|date=September 2024}} In 1955, the German and Danish governments issued the [[Bonn-Copenhagen declarations|Bonn-Copenhagen Declarations]] confirming the rights of the ethnic minorities on both sides of the border.<ref name="Landesportal Schleswig-Holstein-2">{{Cite web |title=Schleswig-Holstein – Urkunde von Ripen |url=http://www.schleswig-holstein.de/DE/Fachinhalte/L/landeskundegeschichte/Chronologie_Augenblicke_Landesgeschichte/1460_VertragRipen.html?nn=80cfdf51-1a24-4512-a0d7-d9cd524787ae |access-date=17 April 2022 |website=Landesportal Schleswig-Holstein |language=de |archive-date=25 April 2022 |archive-url=https://web.archive.org/web/20220425223630/https://www.schleswig-holstein.de/DE/Fachinhalte/L/landeskundegeschichte/Chronologie_Augenblicke_Landesgeschichte/1460_VertragRipen.html |url-status=live }}</ref> Conditions between the nationalities have since been stable and generally respectful.{{cn|date=September 2024}}