ELI5: Explain Like I'm 5

Timeline of events preceding World War II

Imagine you and your friends always hang out together playing in the park. One day, one of your friends starts being mean and pushes you around. This makes you upset, but you try to forget about it and continue playing as usual. However, as time passes, your friend keeps getting more aggressive and starts bullying you and your other friends. Eventually, the situation gets out of control, and you have to ask for help from your family and other adults to stop the bully from hurting you.

In the same way, World War II was a big fight between different countries because of some mean and unfair things that had been happening for a long time. Here's a timeline of what led up to the war:

- In 1919, after World War I ended, the Treaty of Versailles was signed between Germany and the Allies. This treaty blamed Germany for starting the war and made them pay huge amounts of money for damages, disarm their military, and give up some of their territories. This made Germany very angry because they felt they were being treated unfairly.
- In the 1920s, Germany suffered from economic problems and political instability. The Nazi Party, led by Adolf Hitler, promised to make Germany great again by restoring their power and pride. They used propaganda and violence to gain support, and in 1933, Hitler became the Chancellor of Germany.
- In 1935, Hitler began expanding Germany's military power, breaking the Treaty of Versailles. He also started persecuting Jews and other minorities, blaming them for Germany's problems.
- In 1938, Hitler demanded that Germany annex Austria, which had been an independent country until then. The other European powers allowed this to happen because they didn't want another war. This was called the Anschluss.
- Later that year, Hitler demanded that an area in Czechoslovakia called Sudetenland, where many people spoke German, be given to Germany. The leaders of France and Britain agreed to this, in a policy called appeasement, hoping that it would prevent war. However, Hitler continued his aggression and invaded the rest of Czechoslovakia in 1939.
- In August 1939, Germany signed a non-aggression pact with the Soviet Union, promising not to invade each other. This allowed Hitler to invade Poland without worrying about fighting on two fronts. On September 1, 1939, Germany invaded Poland, starting World War II.

In summary, World War II was caused by a mix of grievances from World War I, economic and political instability, the rise of Nazi Germany, and the failure of diplomacy to prevent aggression.