If you want the descriptions of what it was like just after the Atomic bombings in Hiroshima, the source I read got their excerpts from "To hell and back: last train to Hiroshima." [I think it's factually fine. The original book got retracted but I haven't seen anyone object to the second printing, and most of the issues related to the stories of the Enola Gay or the science and not the stories of victims].
As I was reading these horror stories, there was something in my mind that kept just weeping. This was a terrorist attack. Not just against the Japanese but against the whole world. Hundreds of thousands of people died, either instantly vaporized or agononizingly slowly over the course of hours to years. Elderly, women, children, disabled, and even Korean victims of Japanese slavery. All of that was done so the US could intimidate the world [more specifically, the USSR]. It wasn't an unfortunate sacrifice, it wasnt a mistake. It was an act of pure and unfettered terrorism, that gets justified in schools and propaganda outlets.
And they wanted to do it again. Douglas MacArthur wanted to drop 50 along the Korean-chinese border, Eisenhower (or people in the government associated with him at least) essentially threatened the chinese with the same thing. The soviets were threatened on a scale of thousands of hiroshimas before the Cuban missile crisis.
The way I felt when I was reading the accounts of these attacks was the same way I felt when reading about the Nanjing massacre. Almost incomprehensible horrors.
I get not a lot of people will disagree with me here but I just had to get it out because fuck I'm depressed
Edit:I forgot to add. I know this wasn't the worst crime during the war. I don't feel like ranking crimes against humanity but the crimes committed during the Holocaust and the Japanese war of aggression in China were obviously worse. I just wanted to say that because occasionally I get accused of being one of those "Japan [as a whole] is a victim" people
I know the feeling, reading about something horrible happening and wondering how on Earth people were able to do it in the first place. We've got so many ways of dehumanizing others through racism, nationalism etc, but I think we also dehumanize ourselves when we pass the buck on responsibility the way we do - the scientists don't feel responsible, the pilots don't feel responsible, the politicians don't feel responsible, the military planers and commanders etc... nobody's fucking responsible, so this horrible thing that we did becomes treated like a natural disaster or an inevitable outcome that we had no control over.
And a lot of that's by design, and a lot of it is a defense mechanism cooked up by the people who are definitely the most responsible for the thing that was done, but god damn it things didn't need to be that way. It is fully possible to have systems that don't dehumanize everyone they interact with and don't cook up these kinds of horrible actions as default.
Like, take the example of the Soviets rolling into Berlin. They knew that SA would be a problem, that they had a lot of very justifiably angry conscripts and no feasible way to police them at all times, but the leaders of the Red Army were fundamentally humanists, so they imposed very harsh policing on their own people in order to prevent as much of that as they could. And of course it still happened, of course German civilians were harmed during the occupation, but far fewer than the Soviet civilians that were harmed during fascist occupation. Berlin wasn't treated like Nanjing, not even close, and the Red Army ended the war with by far the most prosecution and punishment of criminals within its own ranks of any of WW2's large armies.
When the decision was made to drop the bombs, Japan was done. They had no navy and no air force and we controlled all the waters around their island. We had been "strategically" bombing them for over a year without any resistance, long enough that we had figured out that strategic bombing doesn't actually work. We now know that the Japanese ambassador was trying to go through the Soviets to get a peace deal on the table while we were planning the bombings, all it would have taken from Eisenhower was an indication that he was interested in accepting Japanese surrender and the negotiations could have begun in earnest. Since the Allies held literally all of the cards it was possible to hold, such a deal would have almost certainly wound up being the exact same unconditional surrender that we got after dropping the bombs.