In accordance with the provisions of the Treaty of Versailles, a referendum was held in North Schleswig under the supervision of the inter-allied commission, whereby the population itself should decide whether it belonged to the German Reich or to Denmark.
From 26th Jan to 16th Jun 1920, an inter-allied commission based in Flensburg took over the government and an independent international state was created purely for the purpose of conducting the plebiscite.
In Zone 1 on 10th Feb 1920 the majority of the population voted to become part of Denamrk. Zone 2 voted on 14th Mar 1920 to remain in the German Reich.
Michel 1 to 14 "Coat of Arms and Landscape"
Issued: 25th Jan 1920. Michel 1 to 10 available on sheets (10x10) and sheets (5x10) for Michel 11 to 14. Perf K 14:14½ and watermark Wz 1. Inscribed "SLESVIG PLEBISCIT"
Issued: 25th Jan 1920. Michel 1 to 14, overprint in dark blue. 'C.I.S' refers to the International Schleswig Commission' and the overprint was used to frank official mail from 26th Jan 1920 to 16th June 1920. Michel 1 to 14 can also be found overprinted 'Specimen'. These stamps were valid for use until 16th June 1920.