Why did the Manhattan project began?

Answer 1

The Manhattan project was developed to create a weapon that would persuade the Japanese to surrender. It was hoped that the Japanese citizens would protest and demand the military to stop the war when they saw the devastation from ONE bomb. When the first atom bomb did not persuade them, the second bomb damage and the mounting invasion of Russia finally motivated the Emperor to stop the war. Years after the Manhattan project had been started it became clear that millions of lives would be lost if the war continued by invading Japan.

This dilemma drove the President and his war leaders to consider if using the atom bomb must be used to stop the war and save lives. Obviously it worked. While a little over several hundred thousand lives were killed or severely injured those lives spared the lives of close to a million according to the pattern established during the years before. It was the hardest decision that ever had to be made in the last century.