Answer:
it was the codename for the project which was responsible for creating the atomic bomb
Step-by-step explanation:
Project Manhattan was American research and development, it took place between WWll and its results were shown when the bombs created by it were dropped successfully in Hiroshima and Nagasaki, the destruction that those bombs did make the Japanese emperor surrender and so WWII ended.The boms were condemned (the fat man which was dropped in Nagasaki, the little boy which was dropped in Hiroshima)