Following the invasion of Poland in September 1939, the rapid advancement of German forces led to significant territorial changes. By October 8, the German government officially annexed western parts of Poland, which included regions such as Silesia and Pomerania. The decision to annex these areas stemmed from Adolf Hitler’s long-standing ambition to create a Greater Germany, which necessitated the acquisition of lands populated by ethnic Germans. The territories were integrated into the German Reich through a series of decrees, fundamentally altering their governance, legal systems, and economies.

The annexation was also closely tied to the broader geopolitical context of the time, particularly the secret agreements made between the Nazi regime and the Soviet Union under the Molotov-Ribbentrop Pact. This non-aggression treaty not only allowed for the partition of Poland between the two powers but also emboldened Germany to act without fear of Soviet intervention. The incorporation of these regions was met with a mixture of support from ethnic Germans living in the area and resistance from Polish citizens, leading to harsh reprisals and a climate of fear as the new regime established control.

As Poland was forcibly divided and its western provinces absorbed, the ramifications were severe. The German authorities implemented policies aimed at Germanization, removing Polish identity and replacing it with Nazi ideology. These initiatives included the relocation of German citizens into the newly annexed territories, displacing the native population and instilling a sense of fear and oppression among the Polish populace. This framework set the stage for the extensive atrocities that would unfold during the Holocaust and other wartime actions in occupied territories throughout the duration of World War II.