The Schleswig plebiscites were two
plebiscite
A referendum, plebiscite, or ballot measure is a direct vote by the electorate (rather than their representatives) on a proposal, law, or political issue. A referendum may be either binding (resulting in the adoption of a new policy) or adv ...
s, organized according to section XII, articles 109 to 114 of the
Treaty of Versailles
The Treaty of Versailles was a peace treaty signed on 28 June 1919. As the most important treaty of World War I, it ended the state of war between Germany and most of the Allies of World War I, Allied Powers. It was signed in the Palace ...
of 28 June 1919, in order to determine the future border between
Denmark
Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
and
Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
through the former
Duchy of Schleswig
The Duchy of Schleswig (; ; ; ; ; ) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km (45 mi) south of the current border between Germany and Denmark. The territory has been div ...
. The process was monitored by a commission with representatives from
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
, the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
,
Norway
Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
and
Sweden
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
.
The plebiscites were held on 10 February and 14 March 1920, and the result was that the larger northern portion (Zone I) voted to join Denmark, which occurred 15 June 1920, while the smaller southern portion (Zone II) voted to remain part of Germany.
Order in the plebiscite area was ensured by a joint British-French mission, whose work was awarded the official award of Denmark - '
"Schleswig Commemorative Medal 1920"— "Schleswig Memorial Medal 1920" (other spellings of the name are "Schleswig Plebiscite Medal 1920" and "Den Slesvigske Eringdringsmedaille af 1920").
Background
The Duchy of Schleswig had been a
fiefdom
A fief (; ) was a central element in medieval contracts based on feudal law. It consisted of a form of property holding or other rights granted by an overlord to a vassal, who held it in fealty or "in fee" in return for a form of feudal alle ...
of the Danish crown since the Middle Ages, but it, along with the Danish-ruled German provinces of
Holstein
Holstein (; ; ; ; ) is the region between the rivers Elbe and Eider (river), Eider. It is the southern half of Schleswig-Holstein, the northernmost States of Germany, state of Germany.
Holstein once existed as the German County of Holstein (; 8 ...
and
Lauenburg
Lauenburg (), or Lauenburg an der Elbe (; ), is a town in the state of Schleswig-Holstein, Germany. It is situated on the northern bank of the river Elbe, east of Hamburg. It is overall the southernmost town of Schleswig-Holstein and belongs to ...
, which had both been part of the
Holy Roman Empire
The Holy Roman Empire, also known as the Holy Roman Empire of the German Nation after 1512, was a polity in Central and Western Europe, usually headed by the Holy Roman Emperor. It developed in the Early Middle Ages, and lasted for a millennium ...
, was conquered by Prussia and Austria in the 1864
Second War of Schleswig
The Second Schleswig War (; or German Danish War), also sometimes known as the Dano-Prussian War or Prusso-Danish War, was the second military conflict over the Schleswig–Holstein question of the nineteenth century. The war began on 1 Februar ...
. Between 1864 and 1866, Prussia and Austria ruled the entire region as a
condominium
A condominium (or condo for short) is an ownership regime in which a building (or group of buildings) is divided into multiple units that are either each separately owned, or owned in common with exclusive rights of occupation by individual own ...
, and they formalised this arrangement in the 1865
Gastein Convention. The condominium was terminated due to the
Austro-Prussian War
The Austro-Prussian War (German: ''Preußisch-Österreichischer Krieg''), also known by many other names,Seven Weeks' War, German Civil War, Second War of Unification, Brothers War or Fraternal War, known in Germany as ("German War"), ''Deutsc ...
in 1866.
Article 5 of the Austro-Prussian
Peace of Prague (1866)
The Peace of Prague () was a peace treaty signed by the Kingdom of Prussia and the Austrian Empire at Prague on 23 August 1866. In combination with the treaties of Prussia and several south - and central German states it effectively ended the Au ...
stipulated that a plebiscite should be held within the ensuing six years in order to give the people of the northern part of Schleswig the possibility of voting for the region's future allegiance by allowing regions voting for Danish rule to be restored to Danish administration.
The idea of a plebiscite had been presented earlier. During the early phases of the
First Schleswig War
The First Schleswig War (), also known as the Schleswig-Holstein uprising () and the Three Years' War (), was a military conflict in southern Denmark and northern Germany rooted in the Schleswig–Holstein question: who should control the Du ...
, the secessionist government of
Schleswig-Holstein
Schleswig-Holstein (; ; ; ; ; occasionally in English ''Sleswick-Holsatia'') is the Northern Germany, northernmost of the 16 states of Germany, comprising most of the historical Duchy of Holstein and the southern part of the former Duchy of S ...
had unsuccessfully suggested a plebiscite in parts of Schleswig, but this had been rejected by the Danish government, and during the 1863 London Conference's attempts to defuse the
Second Schleswig War
The Second Schleswig War (; or German Danish War), also sometimes known as the Dano-Prussian War or Prusso-Danish War, was the second military conflict over the Schleswig–Holstein question of the nineteenth century. The war began on 1 Februar ...
, one of the suggestions of
Prussia
Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...
n Prime Minister
Otto von Bismarck
Otto, Prince of Bismarck, Count of Bismarck-Schönhausen, Duke of Lauenburg (; born ''Otto Eduard Leopold von Bismarck''; 1 April 1815 – 30 July 1898) was a German statesman and diplomat who oversaw the unification of Germany and served as ...
was a plebiscite in North Schleswig. Bismarck's initiative was not adopted by the conference, primarily since the option had not been included in the instruction to the Danish delegation. The inclusion of the promise of a plebiscite in the 1866 Austro-Prussian Peace of Prague was a diplomatic concession to Austria, but was not implemented. The reference to it was subsequently dropped in 1877 by Austria and
Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. The 1864 border was confirmed in the 1907 German-Danish Optant Treaty, but Danish North Schleswigers continued to argue for a plebiscite citing the 1866 Peace of Prague.
Danes campaigning for implementation of the plebiscite promise, in the hope that it would result in the area being restored to Danish rule, often made a comparison with the French demand for return of
Alsace-Lorraine. This comparison was regarded sympathetically by French public opinion and, although Denmark had not taken part in the
First World War
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
, there was considerable backing in France for taking up the Danish claims as part of the post-war settlement.
After Germany's defeat in 1918, the Danish government asked the
Allied Powers and the
Versailles Conference of 1919 to include a plebiscite in the disputed North Schleswig region based on
Woodrow Wilson
Thomas Woodrow Wilson (December 28, 1856February 3, 1924) was the 28th president of the United States, serving from 1913 to 1921. He was the only History of the Democratic Party (United States), Democrat to serve as president during the Prog ...
's
Fourteen Points
The Fourteen Points was a statement of principles for peace that was to be used for peace negotiations in order to end World War I. The principles were outlined in a January 8, 1918 speech on war aims and peace terms to the United States Congress ...
as part of the Allied Powers' peace settlement with Germany, and this request was granted by the Allies.
Defining the plebiscite boundaries

The plebiscites were held on 10 February and 14 March 1920 in two zones that had been defined according to the wishes of the Danish government, and based on lines drawn in the 1890s by Danish historian . During the 1880s and 1890s, Clausen had travelled extensively on both sides of a possible future Dano-German border, for which he published two suggestions. Clausen's first line delineated a coherent territory that he expected would vote Danish in a future plebiscite, and the second line (about further south) included a thinly-populated rural region in Central Schleswig, which Clausen believed had potential for assimilation into Denmark, as the population of Central Schleswig was pro-German in allegiance, but also
Danish-speaking.
In 1918, Clausen published a pamphlet "Før Afgørelsen" (''Before the Decision'') in which he strongly advocated that Denmark annex the zone delineated by his northernmost ("first") line, arguing that the territory north of this line was indisputably pro-Danish and should be considered indivisible.
At the same time, he effectively abandoned his second line, as the population of Central Schleswig remained pro-German, and as he considered it vital that the future border should be based on the
self-determination
Self-determination refers to a people's right to form its own political entity, and internal self-determination is the right to representative government with full suffrage.
Self-determination is a cardinal principle in modern international la ...
of the local populace.
In the 1920 plebiscites, Clausen's first line was closely imitated in what became the plebiscite's Zone I, while his second line became the basis of Zone II, although the plebiscite zone was extended to include the city of
Flensburg
Flensburg (; Danish language, Danish and ; ; ) is an independent city, independent town in the far north of the Germany, German state of Schleswig-Holstein. After Kiel and Lübeck, it is the third-largest city in Schleswig-Holstein.
Flensburg's ...
and the town of
Glücksburg. Clausen had excluded both from his two lines.
Zone I was based on Clausen's estimations of the local population's national self-identification. When in doubt, Clausen primarily relied on the wishes of the rural communities, which he considered autochtone (
indigenous), in contrast with the North Schleswig towns, which he considered largely irrelevant due to their smallness and their less-autochtone population, notably the demographics of the town of
Sønderborg
(; ) is a Denmark, Danish town in the Region of Southern Denmark. It is the main town and the administrative seat of Sønderborg Municipality (Kommune). The town has a population of 28,333 (1 January 2025),[naval base
A naval base, navy base, or military port is a military base, where warships and naval ships are docked when they have no mission at sea or need to restock. Ships may also undergo repairs. Some naval bases are temporary homes to aircraft that usu ...]
. In addition, Clausen believed that it would minimize the risk of future conflict if the future border in the
marsh
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
y West Schleswig followed either the
Vidå river or a
dyke. This caused resentment on the German side, as this implied that the town of
Tønder
Tønder (; ) is a town in the Region of Southern Denmark. With a population of 7,477 (as of 1 January 2025), it is the main town and the administrative seat of the Tønder Municipality.
History
The first mention of Tønder might have been in th ...
(Tondern) would be included in Zone I.
Plebiscite preparations
In 1918 and early 1919, the leading Danish political parties argued that the future allegiance of North Schleswig should be decided by a plebiscite, in which the entire region should be counted as one indivisible unit, i.e. vote ''en bloc''. This wish was conveyed to the
Paris Peace Conference in
Versailles
The Palace of Versailles ( ; ) is a former royal residence commissioned by King Louis XIV located in Versailles, Yvelines, Versailles, about west of Paris, in the Yvelines, Yvelines Department of Île-de-France, Île-de-France region in Franc ...
, and became the basis for the plebiscite's Zone I.
During 1919, political wishes in Denmark grew for the extension of the plebiscite area, and the issue became a topic of confrontation between the
Social Liberal
Social liberalism is a political philosophy and variety of liberalism that endorses social justice, social services, a mixed economy, and the expansion of civil and political rights, as opposed to classical liberalism which favors limited g ...
government and its parliamentary support, the
Social Democrats
Social democracy is a social, economic, and political philosophy within socialism that supports political and economic democracy and a gradualist, reformist, and democratic approach toward achieving social equality. In modern practice, s ...
, both parties opposing an extension of the area, versus the
Liberal and
Conservative
Conservatism is a cultural, social, and political philosophy and ideology that seeks to promote and preserve traditional institutions, customs, and values. The central tenets of conservatism may vary in relation to the culture and civiliza ...
opposition which both supported an extension of the plebiscite area. As a compromise, it was decided to request the
Allied Powers to extend the plebiscite until Clausen's second line, which was adapted to include
Flensburg
Flensburg (; Danish language, Danish and ; ; ) is an independent city, independent town in the far north of the Germany, German state of Schleswig-Holstein. After Kiel and Lübeck, it is the third-largest city in Schleswig-Holstein.
Flensburg's ...
and
Glücksburg. In this smaller Zone II, each town – or, in the rural areas, each
parish
A parish is a territorial entity in many Christianity, Christian denominations, constituting a division within a diocese. A parish is under the pastoral care and clerical jurisdiction of a priest#Christianity, priest, often termed a parish pries ...
– was to decide its own allegiance. Two other requests were made, which were only partially followed by the Allied Powers. Firstly, Denmark requested that the plebiscite area's German civil administration be replaced by an international administration. The Allied Powers replaced the German garrisons with a small international force, of 400 French soldiers disembarked from the cruiser ''
La Marseillaise
"La Marseillaise" is the national anthem of France. It was written in 1792 by Claude Joseph Rouget de Lisle in Strasbourg after the declaration of war by the First French Republic against Austria, and was originally titled "".
The French Na ...
'', but the civil administration was only partially replaced in Zone I, and not at all in Zone II. Secondly, Denmark had requested that persons previously expelled from the region should be allowed to vote in the plebiscite. This was intended to allow previously expelled "optants" to vote, i.e. the families of locals who had opted to retain their Danish citizenship and who had consequently been expelled from the area by Prussian authorities. The Allied Powers granted this request but extended it, consequently entitling anyone who had previously lived in the region to vote in the plebiscite. Since a large number of German officials (notably railway officials) had been temporarily stationed in the area, this extension implied that these officials as well as their wives and any children of legal age were entitled to vote in the plebiscite. Since many of the expelled pro-Danish "optants" had emigrated to the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, the net result of this extension was a slight increase for the German results, and it was much more likely for a pro-German emigrant living in Germany to return to the region for the plebiscite than for a pro-Danish expellee who had emigrated to the United States to do the same.
Plebiscite voting and results
On 10 February 1920 the plebiscite was held in ''Zone I'', the later
Northern Schleswig
Northern may refer to the following:
Geography
* North, a point in direction
* Northern Europe, the northern part or region of Europe
* Northern Highland, a region of Wisconsin, United States
* Northern Province, Sri Lanka
* Northern Range, a ra ...
, where 74.9% (75,431 votes) voted to become Danish, while 25.1% (25,329 votes) voted to stay German. In three of the four major towns, especially in the southern region directly at the border with Zone II, German majorities existed, with a German majority as large as 70 to 80 percent in and around
Tønder
Tønder (; ) is a town in the Region of Southern Denmark. With a population of 7,477 (as of 1 January 2025), it is the main town and the administrative seat of the Tønder Municipality.
History
The first mention of Tønder might have been in th ...
(plus southerly
Udbjerg) and
Højer. It was mostly this area that caused controversy after the voting, especially as these towns had been included north of Clausen's first line. Although Clausen correctly estimated Tønder to be vastly pro-German, he considered the town to be economically dependent on its pro-Danish rural uplands, and placed both the town and its uplands north of his first line.
Local majorities for Germany also existed elsewhere: In the small town of
Tinglev, in the city of
Sønderborg
(; ) is a Denmark, Danish town in the Region of Southern Denmark. It is the main town and the administrative seat of Sønderborg Municipality (Kommune). The town has a population of 28,333 (1 January 2025),[Aabenraa
Aabenraa (; , ; South Jutlandic: ''Affenråe'', also known as Åbenrå) is a town in Southern Denmark, at the head of the Aabenraa Fjord, an arm of the Little Belt, north of the Denmark–Germany border and north of German town of Flensburg. It ...]
. Like Tønder and Højer, Tinglev directly bordered Zone II. Both the latter cities, however, lay kind of "isolated" in pro-Danish surroundings.
The vote in Central Schleswig (''Zone II'') took place on 14 March 1920, where 80.2% (51,742 votes) voted to stay German, while 19.8% (12,800) voted to become Danish. Since a Danish majority in this zone was produced in only three small villages on the island of
Föhr
Föhr (; ''Fering'' North Frisian: ''Feer''; ) is one of the North Frisian Islands on the German coast of the North Sea. It is part of the Nordfriesland district in the federal state of Schleswig-Holstein. Föhr is the second-largest North Sea ...
, none of which were near the coming border, the ''Commission Internationale de Surveillance du Plébiscite au Slesvig'' decided on a line almost identical to the border between the two zones. The poor result for Denmark in Central Schleswig, particularly in
Flensburg
Flensburg (; Danish language, Danish and ; ; ) is an independent city, independent town in the far north of the Germany, German state of Schleswig-Holstein. After Kiel and Lübeck, it is the third-largest city in Schleswig-Holstein.
Flensburg's ...
, Schleswig's largest city, triggered Denmark's 1920
Easter Crisis.
A plebiscite was not held in the southernmost third of the province (''Zone III'' which included the region south of Zone II until the
Schlei,
Danevirke
The Danevirke or Danework (modern Danish language, Danish spelling: ''Dannevirke''; in Old Norse language, Old Norse: ''Danavirki'', in German language, German: ''Danewerk'', literally meaning ''Earthworks (archaeology), earthwork of the Danes'') ...
, and the city of
Schleswig
The Duchy of Schleswig (; ; ; ; ; ) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km (45 mi) south of the current border between Germany and Denmark. The territory has been di ...
) as the population was almost exclusively pro-German. The Allied Powers had offered to include this region in the plebiscite, but the Danish government had expressly asked for Zone III to be excluded. The small part of the historical province located south of Zone III was not included in plebiscite plans among the Allied Powers, and the same applied in Denmark, since the extreme south of the former duchy was considered to be a completely pro-German area.
Selected results in detail:
Settlement of the Danish-German border
Directly after the announcement of the results from Zone I, an alternative draft for the frontier was made by the German administrator
Johannes Tiedje. The proposed frontier would have incorporated
Tønder
Tønder (; ) is a town in the Region of Southern Denmark. With a population of 7,477 (as of 1 January 2025), it is the main town and the administrative seat of the Tønder Municipality.
History
The first mention of Tønder might have been in th ...
/Tondern,
Højer/Hoyer,
Tinglev/Tingleff and neighbouring areas and also some parts north from Flensburg – the so-called Tiedje Belt – and would have created almost equal minorities on both sides of the frontier instead of 30,000 to 35,000 Germans in Denmark and 6,000 to 8,000 Danes in Germany.
Tiedje's Line was strongly criticised in Denmark, as it would have transferred a large number of pro-Danish communities south of the future border, and was refused by all parties in the Danish parliament. The plebiscite's entire Zone I was transferred to Denmark on 15 June 1920,
and the territory was officially named the ''South Jutlandic districts'', more commonly
Southern Jutland
Southern Jutland (; ) is the region south of the Kongeå in Jutland, Denmark and north of the Eider (river) in Schleswig-Holstein, Germany. The region north of the Kongeå is called . Both territories had their own ting assemblies in the Mi ...
, although the latter name is also the historiographical name for the entire
Schleswig
The Duchy of Schleswig (; ; ; ; ; ) was a duchy in Southern Jutland () covering the area between about 60 km (35 miles) north and 70 km (45 mi) south of the current border between Germany and Denmark. The territory has been di ...
region.
Gallery
File:Afstemningsplakat3.PNG, A pro-German campaign poster. "We have been Schleswigers for 1,000 years. We will remain Schleswigers. That's why we vote for Germany."
File:Afstemningsplakat4.PNG, A pro-Danish campaign poster in North Frisian "Should we leave this land to the Prussian?"
File:Afstemningsplakat2.png, Pro-Danish post card. Mother Denmark greets South Jutland
File:StevningGenforeningssten.JPG, Memorial in Stevning. "Reunification 1920. By 314 to 7 we voted ourselves home to Denmark".
File:ØsterLindetGenforeningsstenBagside.jpg, Memorial in Øster Lindet. "10 February 1920, 96% of the population of this parish voted for Denmark".
File:Kulturdenkmaeler Wyk Große Straße 006 2016 06 03.jpg, Memorial in Wyk, Föhr
Föhr (; ''Fering'' North Frisian: ''Feer''; ) is one of the North Frisian Islands on the German coast of the North Sea. It is part of the Nordfriesland district in the federal state of Schleswig-Holstein. Föhr is the second-largest North Sea ...
, Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. A reinterpretation of the Deutschlandlied
The "", officially titled "", is a German poem written by August Heinrich Hoffmann von Fallersleben . A popular song which was made for the cause of creating a unified German state, it was adopted in its entirety in 1922 by the Weimar Repub ...
. "... Only in misfortune, will the love f your countryshow if it is strong and true."
File:Erik Henningsen - Danske soldater på march efter indtoget i Nordslesvig - 1920.png, Painting of Danish soldiers returning to Northern part of Schleswig
See also
*
Easter Crisis
*
Schleswig-Holstein question
Schleswig-Holstein (; ; ; ; ; occasionally in English ''Sleswick-Holsatia'') is the northernmost of the 16 states of Germany, comprising most of the historical Duchy of Holstein and the southern part of the former Duchy of Schleswig. Its c ...
*
Danish minority of Southern Schleswig
*
German minority in Denmark
*
History of Schleswig-Holstein
*
Southern Schleswig
Southern Schleswig ( or ', ; ) is the southern half of the former Duchy of Schleswig in Germany on the Jutland Peninsula. The geographical area today covers the large area between the Eider river in the south and the Flensburg Fjord in the no ...
*
1920 Danish constitutional referendum
References
{{Post-WWI plebiscites
Schleswig plebiscites, 1930
1920 Plebiscites
Referendums in Denmark
Referendums in Germany
Schleswig plebiscites
Schleswig plebiscites
Schleswig plebiscites
Schleswig plebiscites
Schleswig plebiscites
Plebiscites, 1920
Plebiscites, 1920
Plebiscites, 1920
Border polls
Schleswig Plebiscites, 1920
Schleswig Plebiscites, 1920