The number people who died as a direct result of the bomb was approximately 200,000. Do you think 200,000 people would have died as the result of an invasion?

Three times that many French people were killed in the war, admittedly by two invasions, one in each direction, but this in a much less populous and much less well-defended country than Japan. And that doesn't count the soldiers of other nations who died in France. Large-scale land invasions against determined resistance are pretty frickin' messy affairs.

Peter