Allenstein, called Olsztyn in Polish, is a town in northern Poland that used German East Prussia stamps, overprinted in two different ways, in 1920 as the town held a plebiscite (vote) to determine whether it would become part of Poland, or remain in German East Prussia, which it had been in since 1772. The citizens chose East Prussia.
The two overprints on Allenstein stamps were:
1. German stamps with ‘PLÉBISCITE / OLSZTYN • ALLENSTEIN’ overprint.
2. German stamps with ‘TRAITÉ DE VERSAILLES ART. 94 et 95’ overprint, inside an oval with the words ‘COMMISSION D’ADMINISTRATION ET DE PLEBISCITE / OLSZTYN • ALLENSTEIN’. These legends refer (in French) to Articles 94 and 95 of the Treaty of Versailles, and the full name of the commission that was handling the plebiscite.
Both overprints were issued on a variety of stamps, in a range of colors, denominated from 5 Pfennig to 3 Marks. A few double overprints and inverted overprints are particularly valuable Allenstein overprint postage stamps.