Reason: It is because the Treaty of Versailles signed at the Paris Peace Conference after World War I was extremely unfair to Germany, which made the Germans have a great revenge; In addition, because of the Great Depression of 1927-1933, countries have sought ways to get rid of the economic crisis. For example, the United States was Roosevelt's New Deal, while Germany, Italy and Japan embarked on the fascist road to get rid of their own economic crisis.
What happened: Hitler conspired with Chamberlain and Daladi in Munich, forcibly ceding the Sudetenland of Czechoslovakia to Germany, and Britain and France adopted a policy of appeasement. In order to finally bring the disaster to the East, the Czechoslovak representative agreed to it without munich crisis.
in August p>1939, the Soviet union and Germany signed a non-aggression treaty between the Soviet union and Germany. On September 1, 1939, German troops attacked Poland on a large scale, and the Soviet Union invaded Poland in the name of establishing the "Eastern Front", and the Second World War broke out in an all-round way. This was a declaration of war between Britain and France, but they did not launch a large-scale attack on the German army (because of the appeasement policy, if they wanted to stop the "sit-in") and quickly occupied Poland.
On June 22nd, 1941, the German army attacked the Soviet Union (Barbarossa) with more than 5.5 million men, 4, tanks and nearly 5, planes. The Soviet Union failed in national defense, failed. By November, the Germans occupied more than 1.5 million square kilometers of the Soviet Union and controlled 4% of the population and most of the industrial areas of the Soviet Union. On the other hand, on December 7, 1941, the Japanese attacked the American naval base at Pearl Harbor in the Pacific Ocean. The Pacific War broke out and the Second World War reached its largest scale.
Result: On August 15th, 1945, the Japanese Emperor issued a surrender letter. On the 28th, the allied forces began to land near Tokyo and other areas, realizing the occupation of Japan. On September 2, the Japanese representative formally signed the unconditional surrender on the USS Missouri docked in Tokyo Bay. On September 9, representatives of Japanese invaders signed an unconditional surrender in Nanjing. The Second World War ended here.
Extended information:
Due to the tragic World War II, according to the agreement of Yalta Conference, in order to maintain international peace and security, the allies led by China, Britain, the United States, the Soviet Union and France initiated the establishment of the United Nations on October 24, 1945, and China, the United States, the Soviet Union, Britain and France became permanent members of the Security Council. Since 1948, the Security Council has authorized more than 6 peacekeeping operations. In addition, the United Nations has successively formulated hundreds of international treaties, ranging from non-proliferation of nuclear weapons to the peaceful use of outer space.
The colonial people in Asia and Africa launched the colonial liberation movement because the old imperialism such as Britain and France suffered heavy losses in World War II. India's independence dealt a fatal blow to the British Empire. Vietnam and Egypt both won the imperialist war. The Middle East and Africa successively became independent of dozens of countries, which eventually led to the complete collapse of the colonial system formed around the world after the great discovery of western geography.
Reference: Baidu Encyclopedia-World War II