World War II: The Start of the Second World War

Lesson Transcript
Instructor: Alexandra Lutz

Alexandra has taught students at every age level from pre-school through adult. She has a BSEd in English Education.

Although the League of Nations was created following World War I with the primary goal of preventing future conflicts, the world was once again engaged in the Second World War within two decades of the first. Explore the factors leading to WWII, and examine key fascist, Axis leaders and Asia's roles in America's declaration of war. Updated: 01/05/2022

What Caused WWII?

Many students have the mistaken impression that World War II was prompted by or linked to the Holocaust - that's the Nazi persecution of European Jews. But, that's not an accurate understanding. To analyze the causes of WWII, we need to look back to World War I. People across the world had said that the Great War, as it was called at the time, was 'the war to end all wars.' At its conclusion, the punishing Treaty of Versailles was supposed to have rendered Germany completely impotent.

The League of Nations was formed to prevent future wars of aggression. There were numerous treaties and agreements signed between different nations in the 1920s. What's more, the Senate's Nye Committee had convinced the United States' government that WWI had been more about money than national security, leading to policies that established America's neutrality in conflicts around the world. In spite of the League being one of Pres. Wilson's priorities, the United States never joined the organization, which consequently hampered its legitimacy as a global body.

How did another world war, more destructive than the first, originate with Germany and go unchecked by the League of Nations? Why in the world did Japan get involved? And, how did America find itself in the midst of a global conflict again?

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  • 0:08 What Caused WWII?
  • 1:26 Unchecked Fascist Aggression
  • 3:52 Trouble in Asia
  • 5:41 Declarations of War
  • 7:45 Lesson Summary
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Unchecked Fascist Aggression

President Wilson had said that the United States' involvement in WWI would 'make the world safe for democracy.' Yet, within two decades, many parts of Europe and Asia had turned away from democracy and embraced one-man or one-party rule, and several of these leaders were not content to stay within their borders.

Benito Mussolini formed the Fascist Party in 1919, and by 1926, he had complete control over Italy. Then, he moved to reestablish the old Roman Empire by invading Ethiopia in October 1935. Yet, the League of Nations looked on; without a military force, they couldn't do much more than embargo certain exports to Italy.

Adolf Hitler was inspired. After consolidating fascist power in 1933, Germany's chancellor tested the limits of the League's power. But, nothing had happened when he withdrew his nation from the League that year, or when he announced Germany's rearmament and compulsory military service in 1935. So, when the League of Nations failed to stop Mussolini's expansion, Hitler turned his own attention outward. In 1936, he sent 32,000 troops, with air support, into an area known as the Rhineland, which was a demilitarized buffer zone created by the Treaty of Versailles.

What did the League of Nations do? It officially disapproved. Then, Germany and Italy signed a military alliance in 1936, also in violation of Versailles. Silence. Germany and Italy both sent aid to the fascist leader of Spain during that nation's civil war, though the League had forbidden foreign involvement. In 1938, Hitler's Anschluss, the reunification of Germany and Austria, went unopposed. Then, in September of 1938, Great Britain and France, eager to avoid another costly war, signed the Munich Agreement approving Germany's occupation of the Sudetenland, which was a German-speaking region of Czechoslovakia, because Hitler promised he wouldn't try to take any more territory. And then, for a few months, Europe thought that might be the worst of it.

Trouble in Asia

But, Europe wasn't the only part of the world dealing with aggressive, ultra-nationalistic leaders. By 1931, China had been embroiled in civil war for four years, and Japan took advantage of this instability. In 1931, they fabricated an excuse to invade Manchuria and seize control of its resources. This reflected Japan's ambitions as a rising imperialist power and mirrored the foreign policy actions repeatedly used by Western powers throughout the era of imperialism. The international community did little to intervene until Japan invaded Shanghai the following year, where a large population of expatriates lived. When the League of Nations protested, Japan withdrew from the organization and sporadic fighting continued.

By 1937, China and Japan were in an all-out war, beginning with the recapture of Shanghai. Quickly, Japanese forces moved in on the capital city of Nanking in 1937, and America evacuated its citizens. The U.S. gunboat, Panay, and three corporate-owned oil tankers were leaving Nanking with the last of the civilians when they were attacked by the Japanese navy. Now, in order to avoid a diplomatic crisis with the United States, Emperor Hirohito claimed that the sinking of the Panay was an accident and apologized.

However, Americans were further horrified by unspeakable Japanese atrocities carried out upon the Chinese capital in the coming weeks, an event known as the 'Rape of Nanking.' The United States and other Western nations imposed severe economic sanctions against Japan and sent aid to China. These sanctions are what set Japan and the United States on a path toward war - the sanctions were the gasoline, while Pearl Harbor was simply a match. Japan was deeply reliant on obtaining resources vital to its war effort in China and its industries from Western nations. Over half of its oil came from the United States and another 10% came from the Netherlands East Indies. Japan also depended on British Malaya for iron ore while French Indochina was a source of coal and rubber. Losing access to these resources makes the Japanese decision to attack a nation with 9-times its industrial capacity and a technologically superior military make much more sense.

By 1939, Japan's war against China was floundering, and the nation, now under the influence of a military mastermind named Hideki Tojo, looked for a way to combat American intervention. In addition, French Indochina, Hong Kong, and Western-controlled treaty ports were all channels used by China to access resources and supplies from the Western powers. For any chance of success in China, Japan needed to close off these supply routes and regain access to the resources necessary for its war industries.

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