General Sherman famously replied to the government of Atlanta that war is cruelty, and you cannot refine it — but citing that one famous line misses the full message:
This letter contains the core message of the “tit for tat” strategy. Once attacked, you ruthlessly fight back until the enemy surrenders. Then you are magnanimous in victory and not one moment beforehand. Sherman’s March to the Sea devastated the South, including Atlanta, but it helped break the Confederacy. In all, the South lost 5% of its population and almost 2/3rds of its property from the war. The South could have ended the suffering at any point by saying “enough.”
Read the whole letter — and think about how few primary sources we ever have students read in school.