As an expert in the field of modern history, I can provide a comprehensive overview of the factors that led to the start of World War II. It is important to note that the causes of the war are multifaceted and complex, involving a combination of political, economic, and social factors that were present in the interwar period. The two dates you mentioned, July 7, 1937, and September 1, 1939, are significant, but they represent different theaters and phases of the conflict.

Step 1: The English Answer

The Origins of World War II

1. **The Treaty of Versailles and its Aftermath:**
The Treaty of Versailles, signed in 1919, was a peace treaty that ended World War I. However, it imposed heavy penalties on Germany, including significant territorial losses, disarmament, and massive reparations. The harsh terms of the treaty created a sense of humiliation and resentment among the German people, which was exploited by Adolf Hitler and the Nazi Party in their rise to power.


2. Economic Instability:
The Great Depression of the 1930s had a global impact, exacerbating economic and political tensions. The depression led to high unemployment rates and widespread poverty, which in turn fueled the rise of extremist political movements in many countries.


3. Rise of Totalitarian Regimes:
The interwar period saw the rise of totalitarian regimes in Germany, Italy, and Japan. These regimes pursued aggressive expansionist policies, which included invasions and occupations of neighboring countries. The aggressive actions of these regimes were largely unchecked by the international community, which was still recovering from the devastation of World War I.


4. Failure of the League of Nations:
The League of Nations, established after World War I to prevent future conflicts, was ineffective in maintaining peace. Its inability to prevent aggression by the Axis powers, particularly Italy's invasion of Ethiopia in 1935, demonstrated its limitations.


5. Rearmament and Military Expansion:
Germany, under Hitler, began a massive rearmament program in violation of the Treaty of Versailles. This, along with the military expansion of Japan and Italy, created an imbalance of power that would eventually lead to conflict.


6. The Appeasement Policy:
The policy of appeasement by Britain and France, particularly in the Munich Agreement of 1938, where they allowed Germany to annex parts of Czechoslovakia, emboldened Hitler and furthered his aggressive ambitions.

7.
The Invasion of Poland:
The immediate trigger for the outbreak of World War II in Europe was Germany's invasion of Poland on September 1, 1939. This act of aggression led to declarations of war by Britain and France against Germany.

8.
The Asian Conflict:
The conflict between Japan and China, which began with the Marco Polo Bridge Incident on July 7, 1937, is often considered the start of the Second Sino-Japanese War. While this conflict was a precursor to the larger global war, it was not the direct cause of World War II in Europe.

9.
Ideological Conflicts:
The ideological differences between the democratic nations and the fascist and militaristic regimes were a significant factor. The desire of the Axis powers to spread their ideologies and establish global dominance was a driving force behind their aggressive actions.

10.
Nationalism and Territorial Disputes:
Nationalism and unresolved territorial disputes from World War I also played a role. Many countries harbored grievances over the outcomes of the war and sought to revise the established borders.

In summary, the start of World War II was a result of a complex interplay of factors, including the punitive measures of the Treaty of Versailles, economic depression, the rise of totalitarian regimes, the failure of the League of Nations, rearmament and military expansion, appeasement policies, and ideological conflicts.

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The two dates most often mentioned as --the beginning of World War II-- are July 7, 1937, when the --Marco Polo Bridge Incident-- led to a prolonged war between Japan and China, and September 1, 1939, when Germany invaded Poland, which led Britain and France to declare war on Hitler's Nazi state in retaliation.read more >>