How did the U. S. joining WWII change the war for France, Great Britain, Germany, Italy, and Japan?

The war changed because the Allies now had another major superpower in the war that could help in Asia and Europe. The United States had great technology and a great large army, however the United States focused on Japan at first. Also due to the US, the allies were able to begin D-DAY together. In 1945 the US made two atom bombs and dropped them on Japan ending WW2

Global in scale and in its repercussions, World War II created a new world at home and abroad. ... Although the war began with Nazi Germany's attack on Poland in September 1939, the United States did not enter the war until after the Japanese bombed the American fleet in Pearl Harbor, Hawaii, on December 7, 1941.

Explanation:

How did USA enter into World War II?  It had occupied French Indo-China and was planning attacks on US naval bases in the Pacific. When Japan extended its support to Hitler and bombed the US base at Pearl Harbour, the US entered the Second World War

- "a new era of american politics began with jackson's election in 1828, but it also completed a grand social experiment begun by the american revolution. nevertheless, jacksonian democracy represented a provocative blending of the best and worst qualities of american society."

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