House of Schaumburg in the context of "Schleswig-Holstein"

Schleswig-Holstein (/ˈʃlɛswɪɡ ˈhoʊlstaɪn/; German: [ˌʃleːsvɪç ˈhɔlʃtaɪn] ; Danish: Slesvig-Holsten [ˌsle̝ːsvi ˈhʌlˌste̝ˀn]; Low German: Sleswig-Holsteen; North Frisian: Slaswik-Holstiinj; 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 capital city is Kiel; other notable cities are Lübeck and Flensburg. It covers an area of 15,763 km (6,086 sq mi), making it the 5th smallest German federal state by area (including the city-states). Historically, the name can also refer to a larger region, containing both present-day Schleswig-Holstein and the former South Jutland County (Northern Schleswig; now part of the Region of Southern Denmark) in Denmark.

Schleswig, known as South Jutland at the time, had been under Danish control since the fifth century. In the 12th century, however, it became a duchy within Denmark due to infighting in the Danish royal house. It bordered Holstein, which was a part of the Holy Roman Empire. Beginning in 1460, the King of Denmark ruled both Schleswig and Holstein as their duke. Schleswig was still part of Denmark, while Holstein remained part of the Holy Roman Empire. In the 19th century, both Danes and Germans believed they had a rightful claim to Schleswig-Holstein. While the population of Holstein and Lauenburg was entirely ethnically German, Schleswig had been predominantly Danish until the late 1700s and early 1800s, when extensive German influence led to the Germanization of South Schleswig. The resulting long-term political and territorial dispute was known as the Schleswig-Holstein Question. In 1848, Denmark tried to formally annex the area. Prussia responded by invading, thus beginning the First Schleswig War, which ended in a victory for Denmark. But in the Second Schleswig War (1864), Prussia and Austria won, and the territory was absorbed into Prussia in 1867. After the German defeat in World War I the Allies required that the question of sovereignty over the territory be submitted to plebiscites (the 1920 Schleswig plebiscites). They resulted in the return of the Danish-speaking North Schleswig to Denmark. The area was subsequently renamed South Jutland, restoring the historical name used before it was changed to Schleswig by Gerhard III of the House of Schauenburg. After World War II, Schleswig-Holstein took in over a million refugees.