Well, the atom bombings were necessary, I don't think we disagree about that. The rest of my post you replied to pointed to some of the extreme nastiness that would have been entailed in a fullscale invasion of the Japanese Home Islands.
And it's possible to argue (from a strictly Yankee POV, always stipulating -- the Southern one being always that Sherman had no business down there, nor Lincoln either) that Sherman's Georgia campaign was necessary, without stipulating to all the notorious frills. It might have been necessary, from a military standpoint, not to leave behind intact railway facilities and equipment, or usable stores of cotton. But the salt and the silverware, and Mrs. McGillicuddy's cow......that was all over-the-top, and administered vindictively. That was what was remembered. My dad told me that Sherman's route was still visible on aerial photographs taken in the 1930's, the damage from the sown salt was that severe.
I differ somewhat from the other posters here. I do remember hearing hard things said about Billy Sherman back in the 1950's and 1960's, when I was living in Louisiana.
As a final thought, it would have been smarter if Sherman had issued Union scrip for the crops and foodstuffs he destroyed. That would have observed at least the punctilio of conscription, and would shrewdly have offered the affected civilians something to look to the Union Government for, if its authority were to be reestablished in the South.
My understanding is that the whole "sown salt" thing is another myth that doesn't stand up to the slightest scrutiny. How much salt would it take to destroy a swath of farmland that extensive? How many wagons to haul it? How many men to spread it?