The secret agreement to divide Poland between Nazi Germany and the Soviet Union.

This source provides an extensive overview of the German invasion of Poland in 1939, marking the beginning of World War II in Europe. It details the political backdrop, including early German-Polish relations, Hitler's shifting foreign policy, and the failed negotiations leading up to the conflict. The text further outlines the military campaign, comparing German and Polish forces, describing the key battles, and explaining the concurrent Soviet invasion of eastern Poland. Finally, it addresses the aftermath and consequences, covering war casualties, mass murders, war crimes committed by German forces, the German occupation, the formation of the Polish government-in-exile and resistance, and the subsequent legal ramifications in the Nuremberg Trials.