World War II (United Socialist States of America)

Buildup
1932: In response to the growing anti-Semitism in Germany, Albert Einstein and his wife move to Britain.

1939: Albert Einstein speaks with British Prime Minister Neville Chamberlain about the construction of an atomic bomb. Chamberlain is uninterested.

The War begins
1939: World War II begins.

1940: France falls to Germany. Great Britain, led by the newly elected Prime Minister Winston Churchill, was left all alone to fight Hitler and Nazi Germany.

Meanwhile, a select group of British scientists begin working on a secret project on a lonely Scottish Isle.

1941: The Empire of Japan launches a surprise attack on Pearl Harbor, wrecking most of the USSA Pacific fleet. The next day, President Long of the USSA declares war on Japan. Following Italy and Germany's declaration of war, the USSA is dragged into the war in Europe.