This pro-German poster depicts a girl waving a Schleswig-Holstein flag, a region lost by Denmark to Germany many decades before and on 20 March 1920 set for a referendum on German or Danish rule. The poster, created by the German painter Paul Haase, is from Flensburg. The result for Flensburg turned out to be 75% of votes in favour of German citizenship.
Denmark had been forced to surrender the Duchies of Schleswig and Holstein as a result of the Second Schleswig War (1864). This meant that large numbers of Danish-minded residents of northern Schleswig (now Sønderjylland) were forced to live under German rule.
At the end of the war the Treaty of Versailles (Art 109) defined that plebiscites, or referendums, should be held in Schleswig to determine the future of the region. Referendums were an opportunity for every member of an electorate to cast their vote on a single issue, usually of national or international relevance. The general assumption was that people of the northern part, Zone 1 (now Sønderjylland), would vote in favour of Danish nationality while the results from the southern regions, Zone 2, remained to be seen. Most were predicted to vote in favour of Germany, but city of Flensburg, could turn out in favour of Denmark.
The fight for votes in Flensburg, the main city of Schleswig, became cutthroat. During the days before the voting streets were filled with Danish, German and Schleswig-Holstein flags, and posters to influence voters were everywhere.