I still don't really buy this whole trade-off idea used to justify dropping the bombs, massacre from above vs massacre on the ground.
https://en.wikipedia.org/wiki/Bombing_of_Tokyo
9-10 March "Operation Meetinghouse", six months prior to the nukes: "Approximately 15.8 square miles (4,090 ha) of the city was destroyed and some 100,000 people are estimated to have died." This was more deadly than either of the atomic bombs, it just required far more planes and pilots.
That's a trite expression but actually a vitally important part of the international law of war. Initiating a conflict is the immoral act, collective self-defence is not. How far back does collective self-defence reach in terms of destroying the enemy's capability to attack you? That is the difficult bit and where so many people take issue with the Israeli use of this justification.
(Unless you want to argue against armed self-defence tout court, that the participants in the defence of the Warsaw ghetto were also murderers etc. etc, which is a self-consistent but rather unusual position)
But making shit stop, and stop right now? That can be useful as opposed to just.
I think we agree, I'm just saying this because I hear way too much about 'right' and 'wrong' with armed conflict. It's all wrong -ALL of it.
That said, had the bombs not been dropped, estimates ran into the millions for Allied casualties and tens of millions for Japanese (civilian + soldiers) casualties.
Ultimately it boils down to an issue of numbers (achieved by expediency).