How did the involvement of the us change the war world war 2?

Answer 1

The United States entry into World War II reversed the balance of power and provided a font of manpower and technological ability that would allow the Allies to be victorious. This ensured the perseverance of democratic ideals (as opposed to fascist ones) and allowed for the continued survival of minorities.

Answer 2

The entrance of the US into WW Two in 1941, changed the entire dynamic of the war. A populous nation, protected by two oceans from Japan and Germany, and allied with England, France's outside forces combined with Soviet forces placed immense pressure initially on Germany. The US had factories to supply itself and its allies with much needed war supplies. Soon American troops were in North Africa and its warships were transporting marines in the Pacific to islands controlled by Japan.By 1944, Germany was in a two front war. Russia at its eastern borders and US & British forces in France.

Hitler had made a fatal error by declaring war against the US as did Japan, although an official declaration was not made. The involvement of the US in December, 1941, caused WW Two to be over less then 4 years. It's clear that if the US did not join the Western allies, and "help" the Soviet Union, the German occupation of France would have continued allowing Germany to focus its power on the Soviets. Japan's dream of ruling the East was shattered due to their own over ambitious war acts. Imperial Japan would have been the uncontested power in East Asia and the Pacific Ocean.