World War I was the cause for World War II I believe that world war 1 led to world war 2. the main reason is the treaty of Versailles. the allies totally screwed Germany and were totally unfair. The allies forbade Germany to have an army of more than 100,000 men, a fleet of more than 36 warships, submarines of any kind, and military air craft. They could not maintain fortifications or military installations within 50km of the Rhine land. And to all that Germany was required to pay large sums of money as reparations for damages that the all ....