Following the defeat of Imperial Germany in World War I, the Allied powers organised two plebiscites in Northern and Central Schleswig on 10 February and 14 March 1920, respectively. In Northern Schleswig 75% voted for reunification with Denmark and 25% for staying with Germany. In Central Schleswig the situation was reversed with 80% voting for Germany and 20% for Denmark. No vote ever took place in the southern third of Schleswig, as it was considered a foregone conclusion that almost all the inhabitants would vote to remain in Germany.
On 15 June 1920, Northern Schleswig was officially reunited with Denmark (see: South Jutland County). The remainder of Schleswig remained part of Schleswig-Holstein, now a province of the Free State of Prussia.
^Wolfgang Benz, Potsdam 1945: Besatzungsherrschaft und Neuaufbau im Vier-Zonen-Deutschland, Munich: Deutscher Taschenbuch Verlag, (=dtv Reihe Deutsche Geschichte der neuesten Zeit vom 19. Jahrhundert bis zur Gegenwart; vol. 4522), p. 262. ISBN 3-423-04522-1