2.9% of all Germans in Poland, and 0.3% of the local population. Towns with particularly high concentrations of German speakers in Opole Voivodeship include: Strzelce Opolskie; Dobrodzien; Prudnik; Głogówek; and Gogolin. In the remaining 12 voivodeships of Poland, the percentage of Germans in the population does not exceed 0.09%: Poland is also the third most frequent destination for migrant Germans searching for work, after the United States and Switzerland. History of Germans in Poland German migration into areas that form part of present-day Poland began with the medieval Ostsiedlung (see also Walddeutsche in the Subcarpathian region). Regions which subsequently became part of the Kingdom of Prussia - Lower Silesia, East Brandenburg, Pomerania and East Prussia - were almost completely German by the High Middle Ages. In other areas of modern-day Poland there were substantial German populations, most notably in the historical regions of Pomerelia, Upper Silesia, and Posen or Greater Poland. Lutheran Germans settled numerous "Olęder" villages along the Vistula River and its tributaries during the 17th, 18th and 19th centuries. In the 19th century, Germans became actively involved in developing the clothmaking industry in what is now central Poland. Over 3,000 villages and towns within Russian Poland are recorded as having German residents. Many of these Germans remained east of the Curzon line after World War I ended in 1918, including a significant number in Volhynia. In the late-19th century, some Germans moved westward during the Ostflucht, while a Prussian Settlement Commission established others in Central Poland. According to the 1931 census, around 740,000 German speakers lived in Poland (2.3% of the population). Their minority rights were protected by the Little Treaty of Versailles of 1919. The right to appeal to the League of Nations however was renounced in 1934, officially due to Germany's withdrawal from the League (September 1933) after Adolf Hitler became German Chancellor in January 1933. WWII After Nazi Germany's invasion of the Second Polish Republic in September 1939, many members of the German minority (around 25%) joined the ethnic German paramilitary organisation Volksdeutscher Selbstschutz. When the German occupation of Poland began, the Selbstschutz took an active part in Nazi crimes against ethnic Poles. Due to their pre-war interactions with the Polish majority, they were able to prepare lists of Polish intellectuals and civil servants whom the Nazis selected for extermination. The organisation actively participated and was responsible for the deaths of about 50,000 Poles. Following