1. Nationalism and Militarism. In the years leading up to World War II, nationalism was on the rise in Europe and Asia. Countries were competing with each other for resources and territory, and they were building up their militaries. This created a climate of fear and distrust, and made it more likely that a conflict would start.
2. The Treaty of Versailles. After World War I, Germany was punished severely by the Treaty of Versailles. The treaty took away much of Germany's territory, and it imposed harsh economic sanctions. This made many Germans angry and resentful, and they were determined to get revenge.
3. The Rise of Fascism. In the 1920s and 1930s, fascist governments came to power in Italy, Germany, and Japan. These governments were ultranationalist and militaristic, and they were determined to expand their empires. This led to conflict with other countries, such as Ethiopia, China, and the Soviet Union.
4. The Failure of the League of Nations. The League of Nations was created after World War I to prevent future wars. However, the League was unable to stop the outbreak of World War II. This was due to a number of factors, including the lack of cooperation from the major powers, the rise of fascism, and the economic crisis of the 1930s.
5. The Holocaust. The Holocaust was the genocide of six million Jews by the Nazis during World War II. This was one of the most horrific crimes in human history, and it played a significant role in the war. The Holocaust convinced many people that the Nazis were evil, and it made it more difficult for them to justify the war.
These are just some of the reasons why people went to war in World War II. The war was a complex conflict, and there were many other factors involved. However, the factors listed above were some of the most significant.