they had no idea if it would work or not. it was a gamble. if it fails then its a morale booster for Japan.
after delivery of the Hiroshima bomb to Tinian island 2 torpedo's from the I-58 submarine sends her to the bottom. out of a crew of 1,197 An estimated 900 make it into the sea. the vessel sinks in approx 11 mins. of those approx 317 survive what was called the biggest shark attack on record. and later one of the most controversial court martial's in Naval history
story
Are you kidding? There was no gamble involved at all. Invading Japan with ground troops would be akin to putting military personnel heads into a lawn mower hoping to eventually stop the blades or run it out of gas. It was that or hitting the motor with a sledge hammer.
Seems a simple logical choice to break the motor.
As for the bomb, that was no gamble. We weren't testing a theory over Hiroshima. The Bomb worked. The only gamble was whether or not the Japanese would capitulate.
The 2 million causalities projected were not guesses, not even educated guesses. They were projections based on previous island invasions.
And of course there is the forgotten matter of Pearl Harbor. Over 3,000 Americans in a matter of hours. Which started the conflict with Japan.
We had no reason to show mercy to the Japanese, military, or civilian. Nor to prolong the war with American casualties.
Truman was once asked by a reporter if he felt any remorse or guilt about dropping the bomb on the poor Japanese. The former President of the USA promptly decked the guy.
Good for Harry.