1.From Isolation to Intervention

The Depression that hit the United States in the 1930ssoon spread all over the capitalist world.It was unquestionably a major factor in bring about Nazism and World WarⅡ.As aggressions of Germany，Italy，and Japan were expanded in 1930s，the US government tried to follow its old isolationist policy.Between 1935and 1937，Congress passed three Neutrality Acts which prohibited the sale of munitions and the lending of money to nations at war.It even outlawed travel by US citizens on belligerents’vessels.The US isolationist policy actually encouraged Hitler to believe that they could rely on American neutrality in the coming war and that this time their victims could not make loans or buy munitions in the US.It also gave the leaders of Japan further reason to believe that the neutral US would not fight for her Open Door or integrity of China.However，when，as a result of German aggression，World WarⅡfinally erupted in 1939，the US Congress repealed the arms embargo and substituted a“cash-and-carry”policy in November of the same year.The policy required that belligerents trading with American merchants transport their goods in foreign vessels and that the goods be paid for before they left American ports.This policy still seemed neutral but it was to the advantage of England.

In 1940，when Franklin Roosevelt won his unprecedented try for a third term as President，almost every country in Western Europe was virtually defeated in a blitzkrieg by Hitler.In Asia Japan’s invasion of China and infiltration into Indochina had showed clearly that Japan’s expansionist policy aimed at domination of the entire Far East and the Pacific.In Sep.1940，the Tripartite Pact was signed in Berlin binding Germany，Italy and Japan together，and thus the formation of the fascist military bloc was completed.All these events convinced most Americans of the need to bring about Germany’s defeat.In 1940，the US began a gigantic naval program to make 200new warships.Roosevelt also asked for new appropriations of＄1，182 million for national defense and called for a production of 5，000planes a year.In August of the same year，the first peacetime draft in US history was enacted，under which about 1.6million men were conscripted during the following year.In March 1941，Congress passed the Lend-Lease Act，which enabled any country whose defense the President considered vital to that of the US to receive arms and other equipment and supplies by sale，transfer，exchange，or lease.In President Roosevelt’s words，this act made the republic the arsenal of world democracy.However，the act helped the fighting against fascism.

Pearl Harbor Raid

When the US was taking steps to help the Allies，Japan suddenly attacked the US naval base at Pearl Harbor in Hawaii on Dec.7，1941.This made America formally enter the war.This sudden blow gave the Japanese naval control of the Western Pacific.Quickly they captured the Philippines Islands and most of Southeast Asia，but they were checked by an American fleet in June 1942at the battle of Midway.Grand strategy，however，directed the main American effort first against the Germans.In Nov.1942，ajoint US—British force landed in North Africa；by the following May that region had been cleared of the enemy.In July 1943，they invaded Sicily and，after swiftly overrunning that island，landed on the Italian mainland in September.By then the King of Italy，with support of the army，had removed Mussolini from his post as Italian Prime Minister and the new government quickly made peace with the Allies and declared war on Germany.On June 6，1944，American and British forces，under the supreme command of the American General Eisenhower，landed in Normandy on the coast of France and gradually pushed the Germans back.Paris was liberated in August，and by the beginning of 1945the Allied forces were advancing into Germany itself.From the east the Russians were steadily advancing.By April of 1945，the Russian armies were outside Berlin.On April 30，1945，Hitler committed suicide.A week later the Germans surrendered.The war in Europe was over.Less than a month earlier，on April 12，President Roosevelt had died of a stroke.

Beginning with the Potsdam ultimatum，which ordered Japan to surrender or faced complete annihilation，a series of significant events brought an early surrender of Japan.On Aug.6，1945，the first US atomic bomb devastated the important Japanese city，Hiroshima.On Aug.8，Russia，fulfilling a previous agreement，declared war upon Japan，and a Soviet army of more than one million men crossed the Chinese border.On Aug，9，another US atomic bomb was dropped on Nagasaki.Next day Japan offered to surrender，on condition that the Emperor of Japan was to remain untouched.The Allies agreed.The surrender was proclaimed on August 14，and the Second World War ended.