It goes both ways. A full on invansion of Japan would’ve costed a lot of lives perhaps more than the bomb killed but on the other hand many innocent lives were lost with the dropping of the bomb
The fugitive slave act of 1793 authorized local governments to recapture escaped slaves and imposed laws restricting the aiding of runaway slaves. This act was provised in 1850 “compromise of 1850” forcing locals to aid in the capturing of slaves and denied the right of slaves to have a trial by jury. The aiding of escaped slaves was also punished more than in the first act
Some examples of this were the Fugitive Slave Act, Preston Brooks's attack on Charles Sumner, and the Dred Scott decision (the part of it which said that African Americans could never be citizens). None of these events tangibly hurt the North or the South.