The rise of totalitarian governments in Europe after World War I, such as Mussolini and Hitler. However the true main cause of WWII was the failure of the Versailles Treaty.

In World War I, there were many debatable reasons as to what caused the war. In World War II, there are also many debatable reasons why war came about. It could have been caused by the failure of the League of Nations to keep peace. The rise of totalitarian governments in Europe after World War I, such as Mussolini and Hitler. However the true main cause of WWII was the failure of the Versailles Treaty.

As the Versailles Treaty was to be signed, Germany was forced to agree that it was guilty of starting the war. The next clause was that Germany had to disarm. The effects of this was that the German army was to be limited to 100,000 men, submarines and aircraft were to be banned, the navy was limited to six battleships, and the Rhineland was to become demilitarized. Germany had to pay reparations, to help the damaged countries rebuild after the war, the amount of $5 billion due May 1, 1921. Germany had hardly enough money to pay amount, overcome great inflation...