As the war breaks out in Europe, public opinion in the USA is mostly opposed to getting involved. In Asia, Japan has expands its empire to Mainland China.
The America First Movement campaigns to maintain the USA out of the conflict. Laws are passed to make arms sales difficult.

Even after the invasion of Poland, the USA stayed neutral. However arrangements were made to allow supplying the United Kingdom.
However, FDR keeps close ties with the British government and makes the “Four Freedoms” speech defending American ideals of freedom and capitalism.

On December 7th, 1941, the Japanese navy launches a surprise attack on the navy base in Pearl Harbor. The USA declares war on Japan. Germany then declares war on the USA.
As a consequence, Roosevelt gave in to racism and signed executive order 9066 forcing 110,000 Japanese-Americans into internment camps.
The Pacific side of the war was a brutal battlefield in the middle of inhospitable terrain, diseases and ruthless enemies.

In Europe, Society reorganized during the war with a greater involvement of women.
The army remains segregated, with battalions of men belonging to the same ethnicity.
Staring in 1942, the tide of war is turning in favor of the Allies.

The Bretton-Woods conference aims to reorganize global finance in 1944, with the American dollar as its cornerstone.
Germany surrenders in May 1945, cementing American military presence in western Europe.
The Manhattan project develops the atomic bomb.

Vice president Harry Truman becomes president after FDR’s death on April 12 1945.
Truman orders atomic bombs to be dropped on Japan in August 1945 which surrenders shortly thereafter.

At the end of the war, 400,000 US servicemen were killed and almost 700,000 wounded.
The war has transformed the USA into a global power with global ambitions. It also sets up a showdown with the other global power, the USSR.