Overprinted stamps of Czechoslovakia
In the aftermath of World War I, many European national borders were redrawn, including those between Czechoslovakia and Poland, two nations that achieved independence in 1918. A plebiscite planned for 1920 was to determine whether the small territory of Eastern Silesia in that border region would become part of Poland or Czechoslovakia. Both of these countries created and issued stamps for Eastern Silesia in February 1920.
Overprinted stamps of Poland
The stamps consist of Czechoslovakian issues overprinted “SO 1920” and Polish issues overprinted “S.O. 1920” (the initials representing “Silesie Orientale”). The Czechoslovakian provisional stamps were valid in the Czech part of Tesin, and in Orava and Spis. The Polish provisionals were valid in the rest of the territory. The plebiscite did not take place, and the region was divided between the two nations by the Conference of Ambassadors.