Had the bomb not been used (in fact, it took TWO to convince them to give up), the warmongering Japanese military would have forced every man, woman and child to the homeland invasion front to die en masse needlessly.
People forget or don’t know that even after Nagasaki hardliners in the Japanese military attempted a coup. They planned to kidnap the Emperor in order to prevent him from cooperating in the surrender. It very nearly succeeded.
That would have likely meant more atomic bombings. (We could roughly produce 3 a month.) Probably invasion of the home islands and tactical atomic bombings to support the invasion. That would have even been dangerous to our ground troops.
A negotiated peace would have left the old Japanese political and social structure in place that could possibly start another war later. The bomb was meant to win the peace as well as the war. I hate to think what the Russians would have done if they took over Japan, which might have happened while we were trying to negotiate this peace. Dropping the bomb was the right thing to do. It saved a lot of American and Japanese lives. The left needs to stop whining about it.