the first manifestation of the European dilemma – a dissolution of the monarchy system in the face of democracy. Totalitarianism, or dictatorship, was the natural byproduct of ego-driven impulses in man coupled with an industrialized armed force. Because Hitler could demand industrial output at will without acknowledging the free-enterprise market, Germany could produce tanks, planes, rockets, etc. without concern. By using the German pride in their Aryan race and by setting the Jewish population up as scapegoats (they were actually the most creative part of the German community), Hitler justified his invasion of Poland, which the other European nations could not ignore.) The Japanese complication came from, again, a belief in racial superiority, coupled with a fading monarchic system.

World War II had many contributing causes. First, a growing sense of nationalism began moving many nations towards aggressive and belligerent foreign policy choices. The resulted in a wave of expansionism that would contribute to Japan, Italy and Germany moving to take over neighboring countries.

Another cause was the rise of Fascism. The main leaders in the fascist movement said that this particular political ideology didn’t lend itself to lasting peace, since conflict was at the core of its philosophy.

These issues came to a head thanks to the Treaty of Versailles. This treaty bankrupted Germany by placing blame for the conflict squarely on its head. Germany was required to pay huge war debts, which bankrupted the country and provided fertile ground for the rise of the Nazi party who preached a gospel of German pride and revitalization. Thanks to the crippling economic crisis caused by the treaty, the legitimate government of Germany lost power and was replaced by Adolph Hitler’s party.

World War II happened largely because two countries were unhappy with the status quo in the world.  These countries were Germany and Japan.  They did the most to start WWII.

Germany was unhappy with the status quo after World War I.  Germany had lost that war and the victorious allies had treated Germany very harshly in the peace treaty that ended the war.  This led to a great deal of anger among Germans and a desire for revenge. 

Japan did not lose WWI, but it was unhappy with the status quo as well.  It wanted to be a major imperial power.  However, the major European powers (and the United States) already had control of most of the areas that Japan wanted to colonize.  These powers were not comfortable with the idea of Japanese expansion.

Thus, WWII began because these countries tried to upset the status quo.  Countries like Great Britain and the US, who were happy with the status quo, fought back to prevent major changes from happening.

If one had to name a particular cause of World War II; it would be the Treaty of Versailles that ended World War I. Germany was treated most unfairly by the terms of the treaty. Germany was forced to accept full responsibility for the cause of the war, and full financial responsibility for its costs. This caused so much bitterness and resentment among the German people that it provided a ready platform for Adolf Hitler. Hitler railed about the unfairness of the Treaty, and also the need of the German people for Liebensraum, or "breathing space." This was the basis for his marching into the Rhineland, and his taking of all of Czechoslovakia when he had been promised the Sudetenland. This should have been sufficient warning to those who opposed him that he would not keep his word, but they were more inclined to appease him. Finally, on September 1, 1939, he invaded Poland, and the war in Europe began.

Strangely enough, the war in Asia with Japan was also largely the result of the Treaty. Japan had entered World War I on the side of the Allies hoping to gain large amounts of German held territory in Asia, but walked away empty handed. This played into the hands of the militant war party in Japan who started a campaign to take Manchuria and large areas of Indochina. When the United States stopped shipments of oil and scrap metal to Japan, the Japanese high command saw war with the United States as inevitable. Adm. Isokuru Yamamoto, who commanded the fleet that attacked Pearl Harbor, had reasoned that the United States did not have a "warrior heritage," and did not have the stomach for a long war. He believed that if the Pacific Fleet could be eliminated, the United States would make peace before the Atlantic Fleet could be repositioned. It was for this reason that Japan attacked Pearl Harbor on December 7, 1941.

Japan had previously signed the Tripartite Pact with Italy and Germany as a result of which, when the United States declared war on Japan, Italy and Germany declared war on the United States within 72 hours.  And the full war was on.

The invasion of Poland in 1939 in usually given as the beginning of World War II, although there were three other wars often seen as the beginning of what is often referred to as the "era of Hitlerian wars."  The Spanish Civil War was one, as was the Italian invasion of Ethiopia, both in 1936.  The following year fighting broke out between Japanese and Chinese troops the night of July 7 at an ancient stone bridge outside Beijing called the Marco Polo Bridge, probably incited by agents of Mao Zedong in his struggle with Chinese Nationalists.  The fighting was seized upon by the Japanese Army in China as an excuse to start a full scale war (the Second Sino-Japanese War), in defiance of the Japanese government.  There had been fighting between the Japanese and Chinese off and on since the 1931 incident in Mukden.

The real root cause of WW II, however, was the outcome of World War I.  The collapse of German morale (due largely to the British blockade) and the military reverses in France due largely to the massive influx of American troops led the German high command to ask for an Armistice.  This was not an actual surrender by the Germans, and their troops were never pushed back to German territory.  The humiliating terms of the Armistice, the political collapse of Germany's government(s), and the economic disaster following the war left the German nation feeling they were undefeated but treated unfairly.  The feeling that the Army did not lose the war but was "stabbed in the back" by socialists (and "Jewish bankers and businesses") at home led to a belief shared by many that the German nation essentially deserved a sort of rematch.  This and the armed rebellions by socialists, put down by the Freikorps, led to the rise of ultranationalist groups such as the Stahlhelm and the National Socialist Worker's Party.  All these groups espoused a rebuilding of industry and the military, and an eventual new war with France and her allies.

Ironically, this was very much the same reaction of France following the Franco-Prussian War of 1870.  The humiliation of the French Army and the seizure of Alsace and Lorraine were actually the true cause of the First World War, as the humiliating terms of the Armistice led to the Second.

There were many causes for World War II. So, I will limit my answer to the most important factors.

1. The treaty of Versailles that ended World War I was something that caused great bitterness among the German people. They were expecting a treaty based upon President Wilson's plan, which was more lenient, but what they got was a treaty that humiliated the Germans. Moreover, they could not afford the treaties terms. Hence, they decided to vote for a person who wanted to rip with the treaty, Hitler.
2. When Hitler became the Chancellor of German in 1933, he started to build up his army and navy, which was against the treaty of Versailles. He also made two important pacts, one with Italy and the other with Japan. He also took back land that was taken from Germany.
3. Most of Europe sought to appease Germany. They knew that what Hitler was doing was wrong according to the treaty of Versailles, but they turned a blind eye. Even Neville Chamberlain, the Prime Minister of Britain believed that the Germans were treated too harshly.
4. The League of Nations, which was set up after World War I to keep peace did nothing. In fact, they were powerless. All the while, there was tension brewing among the nations and Germany's invasion of Poland in 1939 marks the beginning of the war.

Based on thes four points Germany and Japan began World War II with invasions.

There were several causes of World War II. One cause was the German anger with the harsh Versailles Treaty. Germany believed the Versailles Treaty treated them unfairly. This treaty required Germany to pay the Allies $33 billion in reparations. It also required Germany to accept the responsibility for World War I. Germany felt this was unfair because Austria-Hungary started the war by declaring war on Serbia.

Two additional causes of World War II were the Allies ignoring the violations of the Versailles Treaty by Germany and the aggressive actions of the Axis Powers prior to the start of the war. Germany began to violate the Versailles Treaty by building up its military. It also moved its military into the Rhineland. Both actions weren’t allowed in the Versailles Treaty. The Axis Powers became aggressive in the 1930s. Japan invaded Manchuria in 1931 and China in 1937. Italy invaded Ethiopia in 1935. Germany annexed Austria in 1938. Very little was done when these actions occurred. Then, the leaders of Great Britain and France appeased Germany by allowing Germany to take the Sudetenland in 1938 with an agreement called the Munich Pact. When Germany broke their promise to take no more land by taking the rest of Czechoslovakia in 1939, the stage for World War II was set. Italy also invaded Albania in 1939.

Other factors led to the start of World War II. Intense feelings of nationalism emerged in Germany, Japan, and Italy. These countries believed they were superior to other countries and could do almost anything they wanted to do. They also build up their military and had plans to use it. Along with the desire to gain more land, these factors were very significant in leading to the events that were involved in the start of World War II.

There were many factors involved in the start of World War II.