Allenstein was a district in East Prussia centered upon the city of the same name (currently the Polish city of Olsztyn) which overprinted German stamps in April 1920 to publicize a self-determination vote known as a plebiscite. The name is German for “castle on the Alle River”, construction of which was begun by Teutonic knights in 1347 and completed fifty years later. Since 1999, the city has been the capital of the Warmian-Masurian Voivodeship in northeastern Poland; the river is now known as the Łyna. The area has changed hands numerous times throughout its history.
By the early twentieth century, many inhabitants of the region had Polish roots and were influenced by Polish culture; the last official German census in 1910 classified them ethnically as Poles or Masurians. During the period of the German Empire, harsh Germanization measures were enacted in the region. Following World War I, the French and the British were looking for ways to strengthen the new Polish republic as a bulwark against the Soviets. The British and French tried to attach Allenstein to Poland, but the Germans objected strongly, so the East Prussian Plebiscite (Abstimmung in Ostpreußen) was called. The vote in Allenstein was scheduled to take place on July 11, 1920, and was conducted by the German authorities.
The plebiscite asked the voters whether they wanted their homeland to remain in East Prussia, which was part of Weimar Germany, or instead become part of Poland (the alternatives for the voters were not Poland / Germany, but Poland / East Prussia, which itself was not a sovereign nation). All inhabitants of the plebiscite areas older than 20 years of age or those who were born in the area before January 1, 1905, were entitled to return to vote. The plebiscite ended on July 11, 1920 with a majority of the voters voting for East Prussia with only a small part of the territory awarded to Poland, the majority remaining with Germany. The results were a hugely lopsided 362,209 votes (97.8%) for East Prussia and 7,980 votes (2.2%) for Poland. After the plebiscite, attacks on ethnic Polish population commenced by pro-German mobs saw ethnically Polish priests and politicians driven from their homes.
A total of twenty-eight stamps were issued to publicize the Allenstein plebiscite, with the first appearing on April 3, 1920. These were German stamps overprinted with either of two styles. The first fourteen stamps were overprinted with “PLEBISCITE / OLSZTYN / ALLENSTEIN” while the second fourteen read “TRAITÉ / DE / VERSAILLES / ART. 94 et 95” referring to the Articles 94 and 95 of the treaty. International use of the overprinted stamps ceased from August 20, 1920, and German stamps were used thereafter. Scott #25, pictured here, was overprinted with the second style on copies of Germany #112 which was released earlier in 1920. Featuring the old General Post Office building in Berlin with a denomination of 1.25 marks in a nice shade of green, it was printed using the offset method on sheets perforated 15×14½. Aside from the color, I like the fact that this particular stamp is postmarked (probably cancelled-to-order) on the date of the plebiscite — July 11, 1920.