Son, there were many causes but one that remember the most is a treaty called the treaty of Versailles. Let me tell you all about it...
Grandpa, can you tell me what started World War II?
It all started at the Paris Peace conference in June of 1919. Canada, France, Italy the UK and the U.S were a few of the countries involved. The only country excluded from participation in this conference was Germany.
The treaty of Versailles started by excluding germany from the new League of Nations and not letting them join until 1926. It went on to give germany new boundaries and even separate them from the Saar. It took away many of Germany's colonies and even made them lose many of their armed foces and weapons. They even lost ten percent of their land. Germany was punished severly.
When you punish any country that severly, they will retaliate and that's exactly what started world war II.
If the treaty of Versailles helped end World War I, what's the big deal if it punished Germany?
The Germans were obviously unhappy with the treaty so they decided to retaliate. Hitler was able to use the treaty as a way to rise to power as he supported getting rid of the treaty. Even though Germany violated the treaty by trying to expand in population, many people would forgive them because the treaty treated them so harshly.
Although the Treaty of Versailles helped end World War I, it is a perfect example of the consequences of our participation in the war.