Nuvendil said:
Have you even read about the force Japan had amassed to meet a mainland invasion? Operation Ketsugo? And the ferocity of the battles throughout the Pacific? Japan had repeatedly fought with intensity well beyond the point of hopelessness. They had demonstrated their willingness to go to extraordinary, even near suicidal tactics like bonsai charges against far superior numbers, to keep up the fighting. The US had no reason to believe that wouldn't be the case. Seriously, read up on the projected outcomes of Operation Downfall and the measures of Japan in Operation Ketsugo. The Japanese even planned to pull from all males 15 to 60 and all females 17 to 40 to aid in the battle. Casualties were expected to be extraordinary. Also, they anticipated they would likely need nukes or near-equal destructive weapons to succeed without casualties climbing to outright ludicrous levels. |
Japan was pretty much on its knees by this point in the war though, the US had them effectively surrounded and cut off from resupply/oil/etc.
From here
According to an account by Walter Brown, assistant to then-US secretary of state James Byrnes, Truman agreed at a meeting three days before the bomb was dropped on Hiroshima that Japan was “looking for peace”. Truman was told by his army generals, Douglas Macarthur and Dwight Eisenhower, and his naval chief of staff, William Leahy, that there was no military need to use the bomb.
“Impressing Russia was more important than ending the war in Japan,” says Selden.