There were several complex causes that contributed to the outbreak of the Second World War. Some of the main factors include:
1. Treaty of Versailles: The Treaty of Versailles, which ended World War I, imposed heavy reparations and limitations on Germany, which created economic and political instability in the country and contributed to the rise of Hitler and the Nazi Party.
2. Appeasement: The policy of appeasement pursued by Great Britain and France towards Nazi Germany, which allowed Hitler to expand his territory and strengthen his military power without any opposition.
3. Axis Powers: The formation of Axis Powers consisting of Germany, Italy and Japan, which led to the emergence of aggressive expansionist policies that threatened the security of other nations.
4. Failure of League of Nations: The League of Nations, which was created after World War I to maintain peace and resolve conflicts, failed to address the aggressive actions of Germany, Italy and Japan, undermining its credibility and effectiveness.
5. Non-Aggression Pact: The Non-Aggression Pact signed between Germany and the Soviet Union, which allowed Hitler to invade Poland and start the war.
These are some of the major causes of the Second World War, but there were many other factors at play as well.