The event that marked the start of World War II was:
Germany's invasion of Poland.
1. Germany's invasion of Poland on September 1, 1939, triggered the beginning of World War II.
2. This invasion led to Britain and France declaring war on Germany on September 3, 1939, setting off a chain of events that escalated into a global conflict.
3. The invasion of Poland by Germany is often referred to as the "September Campaign" and is considered the immediate cause of World War II in Europe.
4. This aggressive action by Germany violated international agreements and treaties, resulting in widespread conflict and the involvement of multiple nations in the war.
By understanding the significance of Germany's invasion of Poland, we can recognize its pivotal role in starting World War II.
