In 1939, the scientific community discovered that the Germans had found the secret to split a uranium atom. This they thought would make them capable of producing a bomb with power of incredible destruction.
Enrico Fermi and Albert Einstein fled the Nazi Germany to US to escape death. They wanted to inform the President of the United States about the atomic bomb technology with the opponent Axis Powers.
Fermi and Einstein tried to press upon the necessity to start an atomic research program with the then President Roosevelt. Roosevelt agreed and in 1941 America received the sanction of the Manhattan Project.
In the end of the ear 1972, Fermi along with a group of Physicists conducted the first controlled nuclear chain reaction at the University of Chicago. Since then the Manhattan project progressed at a rapid speed. About $2 billion dollars had been spent in the development of the atomic bomb. The project had employed over 120,000 people in America and the project had to be kept a secret somehow.
Roosevelt and Churchill agreed for secrecy and decided that Stalin to be kept uninformed. There was no awareness of something of this sort being existent and thus there was no debate. Only the most important and trustworthy scientists working on the project knew about it and all the 120,000 employees were kept uninformed about the bomb.
Interestingly, Vice President Truman did not know about the project until he became President himself.
On July 16, 1945 the bomb was tested by Robert J Oppenheimer at Trinity test site in New Mexico.
Impact of the trial
During the test, clouds formed by the bomb reached 40,000 feet height.
Windows of houses over 100 miles away was broken.
The test was successful and fake news about ammunition dump being exploded in the desert was created to hide the test.
The rest is history.