John Kerry is the 1st American Secretary of State or U.S. Government official to lay a wreath at the Hiroshima Memorial. After over 70 years, the U.S. Has recognized the tragedy of the over 100,000 civilian casualties that resulted. The total civilian casualties from U.S. Bombings over Japan was well in excess of 500,000. But, the greater tragedy to the world was that this event unwittingly triggered the nuclear arms race with the Soviet Union.
This analysis is mostly about the affect of the success of the atomic bomb test on our diplomatic strategy with the Soviet Union rather than its military justification. During the so-called "fog of war" dropping of the bombs on Japan may have been a result of a strong emotional hatred of Japan after almost 4 years of war.
The military situation did not justify the dropping of the bombs according to quotes from our most famous military leaders. A fruitful way to begin is to note General Eisenhower's recollection of the Potsdam discussion at which Stimson told him the weapon would be used against Japan:
"During his recitation of the relevant facts, I had been conscious of a
feeling of depression and so I voiced to him my grave misgivings,
first on the basis of my belief that Japan was already defeated and
that dropping the bomb was completely unnecessary, and secondly
because I thought that our country should avoid shocking world
opinion by the use of a weapon whose employment was, I thought,
no longer mandatory as a measure to save American lives. It was my
belief that Japan was, at that very moment, seeking some way to
surrender with a minimum loss of "face.".......
"It wasn't necessary to hit them with that awful thing," Eisenhower
Concluded.....before the atomic bomb was dropped each of the Joint
Chiefs of Staff advised that it was highly likely that Japan could be