How did WW1 Start? | Causes of the First World War?

The First World War started because some countries were angry and had a big fight that spread to many others.

Imagine you're in a playground, and you have a best friend who gets into a fight with another kid. Suddenly, your whole group starts fighting too, just because they wanted to help their friend.

That's kind of what happened with the countries in Europe. There were allies, like friends who promised to help each other if someone got into trouble. The main ones were France and Russia, and later Germany joined them.

One day, a country called Austria-Hungary was upset with another country called Serbia. They wanted revenge for something that happened, it was like when you kick the person who tripped you. So they sent an ultimatum, which is like saying, "You have to do this or we're going to fight!"

Serbia said no, and then Austria-Hungary started fighting with Serbia. Because of their promises, other countries joined in, just like when your friends join the fight on the playground.

Soon, there were a lot more people fighting, that's why it became World War!