causes of WWII

The immediate Causes of World War II are generally held to be the German invasion of Poland, and the Japanese attacks on China, the United States, and the British and Dutch colonies. In each of these cases, the attacks were the result of a decision made by authoritarian ruling elites in Germany and Japan. World War II started after these aggressive actions were met with an official declaration of war, armed resistance or both.
The Nazi Party came to power in Germany by democratic means, although after acquiring power they eliminated most vestiges of Germany's democratic system. The reasons for their popularity included their renouncement of the Treaty of Versailles (particularly Article 231, known as the "Guilt Clause"), which had placed many restrictions on Germany since the end of the World War I; staunch anti-communism; the Dolchstosslegende; and promises of stability and economic reconstruction. They also appealed to a sense of Germanic identity, superiority and entitlement, which would play an important role in starting the war, as they demanded the integration of lands they considered to be rightfully belonging to Germany. Hitler was portrayed by himself, his party, and his book Mein Kampf as an almost otherworldly savior for the German people.
Imperial Japan in the 1930s was largely ruled by a militarist clique of Army and Navy leaders, devoted to Japan becoming a world colonial power. Japan invaded Manchuria in 1931 and China in 1937 to bolster its meager stock of natural resources and extend its colonial control over a wider area. The United States and the United Kingdom reacted by making loans to China, providing covert military assistance, pilots and fighter aircraft to Kuomintang China and instituting increasingly broad embargoes of raw materials and oil against Japan. These embargoes would potentially have eventually forced Japan to give up its newly conquered possessions in China or find new sources of oil and other materials to run their economy. Japan was faced with the choice of withdrawing from China, negotiating some compromise, developing new sources of supply, buying what they needed some where else, or going to war to conquer the territories that contained oil, bauxite and other resources in the Dutch East Indies, Malay and the Philippines. Believing the French, Dutch and British governments more than occupied with the war in Europe, the Soviets reeling from German attacks and that the United States could not be organized for war for years and would seek a compromise before waging full scale war, they chose the latter, and went ahead with plans for the Greater East Asia War in the Pacific. [1]
The direct cause of the United States' entry into the war with Japan was the attack on Pearl Harbor on December 7, 1941. Germany declared war on the United States on December 12, 1941.

For the western world, WWII(1939-1945) started when the Nazi Germany began to slaughter millions of Jews, also known as the HOLOCAUST. then it also invlove with Soviet and Africa. the worst battle was D-Day. It was the bloodiest day in the entire history warfare. Hitler then commited suicide. And president Roosevelt died before he can see the blast of the atomic bomb.
On the eastern side, Japan started to invade China, then Japanese took control the coast line of china. The worst battle on the eastern side was the battle of Iwo Jima and Okinawa. Many soldiers on both sides died fighting. In the end, august 6 and august 9, America dropped 2 atomic bombs, each on Nagasaki and Hiroshima. Then Emperor Hirohito surrendered. Truman was the president by that time