Course of events which lead to World War II were:
1. Unjust Treaty of Versailles: The Treaty of Versailles, which was concluded at the end of the First World War was very unjust. That treatment meted out to Germany, Austria-Hungary and Turkey was revengeful. Therefore, it was resented by Germany and her allies.
2. Rise of the Fascist Powers: Rise of Fascist powers in Germany, Italy and Japan was also responsible for the Second World War. The Nazis in Germany and the Fascists in Italy loved war and thought it to be the best means of their progress. So, they adopted an aggressive policy which led to the Second World War.
3. Insult of Germany: Soon after World War Ist, France humiliated Germany at every step. So, Germany wanted to pay her the same coin.
4. Policy of Appeasement: The Western powers adopted a policy of appeasement towards Germany, Japan and Italy, It encouraged them to adopt war like tendencies. Had they been checked in time, there would have been perhaps no Second World War.
5. Italian Invasion of Ethiopia: Italian invasion of Ethiopia in 1939 increased tension among European countries.
6. German Occupation of Austria and Czechoslovakia: German occupation of Austria in 1938 and that of Czechoslovakia in 1939 made the Second World War inevitable.
7. German invasion of Poland: German invasion of Poland in 1939 forced both England and France to give up the policy of appeasement. They were compelled to declare war against Germany on September 3, 1939. It was the start of the Second World War.