Answer:
Many people would commonly say "The fall of France" But this is incorrect "The fall of France" Took place in the middle of WW2 which therefore couldn't have been the cause of the start of WW2.
Rather a mix of few events and things actually started World War 2. For a world war as deadly as this one there need to be not just one reason to start it. We need to have a good understandable reason. to mention 3 One reason was failure of appeasement.
Failure of appeasement: Appeasement means giving in to someone provided their demands are seen as reasonable. During the 1930s, many politicians in both Britain and France came to see that the terms of the Treaty of Versailles had placed restrictions on Germany that were unfair.
The second reason was Failure of treaty of Versailles.
Failure of treaty of Versailles: The principle reasons for the failure of the Treaty of Versailles to establish a long-term peace include the following:
1) the Allies disagreed on how best to treat Germany.
2) Germany refused to accept the terms of reparations.
3) Germany's refusal to accept the “war-guilt” clause, Article 231.
Last but not least German invasion of Poland.
German invasion of Poland: The Invasion of Poland, known in Poland as the September Campaign or the 1939 Defensive War, and in Germany as the Poland Campaign, was an invasion of Poland by Germany that marked the beginning of World War II.
