During the time between the breaking out of the Second World War and American's attending the war, American was unwilling to attend the war because of the power of the isolationism group and the expansion of the fascist countries such as Germany, Japan, and Italy. So America carried out fence-sitting policy. In fact, this connived the fascist countries'aggression. The president Roosevelt had realized American's danger that the fascist countries brought. After the First World War, the American government began to prepare to attend the war and fought against the fascism under the lead of Roosevelt. Especially after the Second World War broke out, America took positive actions to fight against fascist countries and help the attacked countries. They prepared to began a world war. America's preparations to attend the war largely encouraged the people in British, France, and Russia. They destroyed Hitler's air war and lightening war, enlarged the union of anti- fascism and saved much time to prepare to attend the war. America's preparation before the second the Second World War affected the process of the second world war to a certain extent.The paper includes five parts:The first part is mainly about America's fighting against the fascist countries. Because of the power of the isolationism group and the expansion of the fascist countries, America carried out fence-sitting policy. The president Roosevelt had realized American's danger that the fascist countries brought. So he led his army fighting against the activities of Germany, Japan and Italy. After the Second World War broke out, he fought against the fascist countries on politics, economy, diplomacy, and military affairs.The second part is mainly about America's helping the attacked countries and building the anti-fascism union. President Roosevelt carried out fence-sitting facially and helped British, France, Russia, and China with all kinds of methods. With the development of process of the war, France fell into enemy's hand. British was likely to fail. The war between Russia and Germany broke out. All these startled America. So America attended the war and all anti-fascism counties united.The third part is mainly about the defense system in America and the west hemisphere. In Latin-America, facing the attacking from the fascist countries through economy, politics, and thoughts, America appealed the union of the west hemisphere to strengthen the defense of the west hemisphere.The fourth part is mainly about America's preparation for the war. Because of the power of the isolationism group and the expansion of the fascist countries, America carried out fence-sitting policy. President Roosevelt abolished fence-sitting law, made war plan and the strategy of the whole world, took positive actions to prepare for the war. The fifth part is mainly about the negotiation between America and Japan and Pearl Harbor Affair. After Germany attacked Russia, the relationship between America and Japan went into a new stage. America firmly objected Japan to establish Asia union. So Japan attacked Pearl Harbor. America then attended the war. |