8. Germany and the Soviet Union in the Invasion of Poland (1939)
In August 1939, Nazi Germany and the Soviet Union signed the Molotov-Ribbentrop Pact, a non-aggression agreement that included a secret protocol dividing Eastern Europe into spheres of influence. On September 1, 1939, Germany invaded Poland from the west, and on September 17, the Soviet Union invaded from the east, leading to the partitioning of Poland between the two nations. This unexpected collaboration shocked the world and significantly altered the course of World War II. (britannica.com)
