labour camps, while Germans were settled in pursuit of . Two thousand Polish intellectuals, politicians, and businessmen were murdered in the in 1940 as part of a Poland-wide Germanization program. Silesia also housed one of the two main wartime centers where medical experiments were conducted on kidnapped Polish children by Nazis. Czech Silesia was occupied by Germany as part of so-called Sudetenland. In Silesia, Nazi Germany operated the Gross-Rosen concentration camp, several prisoner-of-war camps for Allied POWs (incl. the major Stalag VIII-A, Stalag VIII-B, Stalag VIII-C camps), numerous Nazi prisons and thousands of forced labour camps, including a network of forced labour camps solely for Poles (), subcamps of prisons, POW camps and of the Gross-Rosen and Auschwitz concentration camps. The Potsdam Conference of 1945 defined the Oder-Neisse line as the border between Germany and Poland, pending a final peace conference with Germany which eventually never took place. At the end of WWII, Germans in Silesia fled from the battle ground, assuming they would be able to return when the war was over. However, they could not return, and those who had stayed were expelled and a new Polish population, including people displaced from former Eastern Poland annexed by the Soviet Union and from Central Poland, joined the surviving native Polish inhabitants of the region. After 1945 and in 1946, nearly all of the 4.5 million Silesians of German descent fled, or were interned in camps and expelled, including some thousand German Jews who survived the Holocaust and had returned to Silesia. The newly formed Polish United Workers' Party created a Ministry of the Recovered Territories that claimed half of the available arable land for state-run collectivized farms. Many of the new Polish Silesians who resented the Germans for their invasion in 1939 and brutality in occupation now resented the newly formed Polish communist government for their population shifting and interference in agricultural and industrial affairs. The administrative division of Silesia within Poland has changed several times since 1945. Since 1999, it has been divided between Lubusz Voivodeship, Lower Silesian Voivodeship, Opole Voivodeship, and Silesian Voivodeship. Czech Silesia is now part of the Czech Republic, forming the Moravian-Silesian Region and the northern part of the Olomouc Region. Germany retains the Silesia-Lusatia region ( or ) west of the Neisse, which is part of the federal state of Saxony. The region was affected by the 1997 Central European flood. Geography Most