of the votes were in favour of Germany. The city and the larger part of the Rybnik district were attached to Poland. Rybnik thus became Polish-ruled for the first time since 1788. Within the Second Polish Republic of the interwar period, Rybnik was part of the Silesian Voivodeship and enjoyed far-reaching political and financial autonomy. In 1933, brothers Karol and Antoni Szafranek, eminent Polish musicians, founded a music school, today known as the Karol and Antoni Szafranek Secondary and Tertiary State School of Music. During the joint German-Soviet invasion of Poland, which started World War II, in September 1939, Rybnik was captured by Germany, and the Einsatzgruppe I entered the city to commit atrocities against Poles. Under German occupation the city was directly annexed into Germany. The population was ethnically categorized and either "re-Germanized" or disfranchised and partially expelled into the General Government (German-occupied central Poland). Local teachers and school principals were among Polish teachers and principals murdered in Nazi concentration camps. The Germans operated a Nazi prison in the city. The Polenlager No. 97, a forced labour camp for Poles, was operated in the city from 1942 to 1945. In the camp, the Germans mainly held children whose parents were either arrested or deported to Germany, and also elderly people. Nevertheless, the Polish resistance movement was active in Rybnik. In the final stages of the war, in January 1945, the Germans murdered 385 prisoners of the Auschwitz concentration camp in the city during a death march. After the eventual German defeat which ended World War II in the European theatre of war in 1945, Rybnik was once more integrated into Poland, the territory of which was shifted westward on Joseph Stalin's initiative. Rybnik thus ceased to be German-Polish border city. A large portion of ethnic Germans from Rybnik eventually settled in the West German city of Dorsten, which eventually became one of Rybnik's twin towns in 1994. In the post-war period, coal mining continued to gain importance. Under Poland's communist rule in 1945–1989 the city was projected to grow as a main mining centre of southern Poland. The 1970s saw the construction of an important coal-fired power plant. A reservoir on the river Ruda was constructed to provide it with cooling water. In 2002, the University of Economics (Akademia Ekomomiczna), the University of Silesia (Uniwersytet Śląski), both in based Katowice, and the Silesian Polytechnic University (Politechnika Śląska) based in