The advance of the Red Army into the territory of the Reich resulted in flight, deportation and later also in the expulsion of most East Prussians. They were exposed – sometimes for years – to cruelty and arbitrariness. With the destruction, the tripartite division of the province and the extensive population exchange, the cultural area, developed over centuries, underwent a fundamental change.
The "Great Flight" began in January 1945, when the Eastern front collapsed. In the icy cold, the population fled west by train, trek, on foot or by ship. After the complete conquest of the province, the "wild” expulsions began in spring 1945. Thousands of civilians, mainly women, were deported and compelled to do forced labour. The Potsdam Agreement in August 1945 approved of the expulsions, and also of the remaining Germans, but without mentioning East Prussia explicitly. These coercive measures and expulsions were the result of the war of annihilation started and carried through by Germany. The first victims of this war were the inhabitants of the occupied Polish territories.