Oppenheimer was doing his independent research on nuclear fission with Edward Teller and other scientists. December 1940. Apart from the Uranium-235 isotope, another radioactive element was discovered which scientists believe could also be used to make nuclear weapons. The name of this element was Plutonium. On 11th October 1941 American President sends a message to British Prime Minister Winston Churchill saying that both countries should collaborate for atomic development.
Not even 2 months later that on 7th December 1941, Japan attacked Pearl Harbor and America officially entered World War 2. American President Roosevelt announced that America will become a part of the Allied powers who were fighting against Germany and Japan. But at this point in time, it becomes clear that the scientific mission of developing nuclear weapons had turned into a military mission.
America spent $2.2 billion on this one project. Taking inflation into account, it is equivalent to $24 billion today. Almost 2 trillion Indian rupees. The American military had an engineering wing the Army Corps of Engineers. It made ports and airfields for the army. Its involvement was approved by President Roosevelt in June 1942.
Now, the office of the North Atlantic Division was in Manhattan, New York City. And when they got the responsibility to make nuclear weapons, they made their headquarters in the same building, on the 18th floor. These headquarters were named Manhattan Engineer District and from this point in time, the Manhattan Project officially started. The date was 13th August 1942.
