There were members of our family who were on their way to Japan when the first bomb was dropped. (They were actually on a ship headed for Japan.) Their commanding officer lined them up & told them, “Look to your right, then to your left. We are invading Japan. They are prepared to kill one out of every three of us.” - My father was a hardened combat veteran of N. Africa, Sicily, Italy & Germany. If Truman hadn’t had the guts to use those bombs; I’m sure Daddy would have ended up in Japan. I wasn’t born until AFTER the war.
I remember a veteran talking about some Pacific invasion where his CO told him "Our casualties are going to be 50%." Both he and his buddy looked at each other and said "You poor bastard." He told that in answer to a question about being scared. You always thought the other guy would get it.