Why world war 2 happened? | The Real reason

World War II was a significant event in world history that involved more than 30 countries. The conflict started when Nazi Germany, led by Adolf Hitler, invaded Poland in 1939. This aggression prompted Great Britain and France to declare war on Germany. But what actually happened during the War? Which countries were taking part in it? Watch this video with Dhruv Rathee to find out as he explains in detail the events of World War 2.