After World War I, Germany was stripped of its territories of Alsace-Lorraine and Danzig. Whats more, many districts in the south and east of the province of East Prussia, the birthplace of Prussia and the home of the Teutonic Order, were allowed to vote on whether to remain in Germany or join the newly-created Polish nation. On July 11th, 1920, the plebiscite was held and the population of East Prussia voted overwhelmingly to remain German.
East Prussia changed hands numerous times throughout history. First inhabited by the pagan Old Prussians, the Teutonic Order, Kingdom of Poland, Duchy of Prussia, and Germany all owned Prussia at various points before the 20th century. As a result, a large Polish minority inhabited the territory, and in some districts the majority of the population spoke Polish. After World War I, districts in East Prussia were put under the jurisdiction of commissions made up of the victorious allied powers. These nations were charged with carrying out a referendum in each of the several districts on whether that district would join Poland or remain in Germany. In the months leading up to the vote, pro-German groups engaged in terrorism and intimidation against the Polish population. German associations attacked Polish officials and activists in the hopes of discouraging the ethnically Polish from voting. Further, the Germans launched a propaganda campaign warning the population that they would suffer economic disaster and would be forced to join the Polish Army if the area voted to join Poland. As any person who was born in the area in question was allowed to vote, many Germans who lived in the west returned to East Prussia to cast a vote in the plebiscite. The allied commission did little to stop the unfair practices of the German campaign, as the British officials running the commission feared a Europe dominated by France if Germany lost too much territory. The voting itself was subject to tampering. German polling officials would declare pro-Polish votes as invalid and add dead Germans to the voter rolls. Further, voters were observed by German police and many feared reprisals if they voted to leave Germany. The results of the plebiscite reflected the flaws in the voting process. In all, 98% of the total votes were to remain in Germany and in no district were there more than 20% of the votes for Poland.
While the plebiscite was certainly unfair and flawed, it is likely that most of the districts would have voted to remain in Germany even without tampering. Most districts had a majority German-speaking population, and even in the ones that did not many were discouraged from voting for Poland by that nation’s comparative economic underdevelopment and war with the Soviet Union. In the end, though, Germany would lose East Prussia in twenty five years, and no plebiscite was held for them to corrupt. As the Red Army advanced into Germany, it pushed most of the ethnic Germans westward, in the process ethnically cleansing the region of its non-Polish residents. East Prussia would then be added to the reconstituted Poland, a Soviet puppet state. A millennia of partial or complete German rule was ended within a year by the most destructive war the world has ever seen.