when did denmark lose schleswig and holstein to prussia
History of Schleswig-Holstein In March 1848 these differences led to an open uprising by the German-minded Estate assemblies in the duchies in support of independence from Denmark and of close association with the German Confederation. The military intervention of Prussia helped the uprising: the Prussian army drove Denmark's troops from Schleswig and Holstein.
Danish nationality law On December 18, 2014, Parliament passed a bill to allow Danish citizens to become foreign nationals without losing their Danish citizenship, and to allow foreign nationals to acquire Danish citizenship without renouncing their prior citizenship. A provision in the bill also allows former Danish nationals who lost their citizenship as a result of accepting another to reobtain Danish citizenship. This provision expires in 2020. A separate provision, lasting until 2017, allows current applicants for Danish citizenship who have been approved under the condition they renounce their prior citizenship to retain their prior nationality as they become Danish citizens. The law came into force on September 1, 2015.[6]