The attack on Poland is what started World War 2 when France and Great Britain declared war on Germany. Here's a breakdown of how it happened:
1. Germany invaded Poland on September 1, 1939, using blitzkrieg tactics to quickly overwhelm Polish defenses.
2. This invasion of Poland led France and Great Britain to honor their alliances with Poland and declare war on Germany on September 3, 1939, marking the beginning of World War 2.
3. The invasion of Poland by Germany was a significant event that triggered a chain reaction of alliances and military actions, ultimately escalating into a global conflict involving multiple countries and lasting until 1945.
So, in the context of the question, the attack on Poland by Germany was the event that directly led to France and Great Britain declaring war on Germany, thus starting World War 2.
