Answer:
Albert Einstein was a German, Jewish scientist escaping Europe during WWII. When he arrived in the U.S. he informed the government that the Germans were researching how to constuct an atomic bomb. The U.S. started the Manhattan Project, headed by J. Robert Oppenheimer, to do the same thing. The atomic bomb was originally built to be used on the Germans, but by the time it was finished the war with Germany was over, so the bomb was used on Japan to end that war instead.