In many history textbooks some historians argue that dropping the nuclear bombs was the most humane way to end the war with the least casualties. The reason being Japan’s proud tradition of never surrendering and if America had invaded the Japanese mainland many more civilians would have died. But is this the most accepted theory today? Are there any sources, either Western or Japanese that assert or deny this theory? Also was there an alternative way to end the war aside from invasion or bombs that was dismissed? Any information would be greatly appreciated.
Our resident nuclear expert u/restricteddata has written an older answer to a fairly similar question that comes from this section of our FAQ-- you can see that this is a popular question! The thing about it is that it's not clear to historians that the atomic bombings are what actually ended the war -- the Japanese government didn't have much time to actually figure out what was going on with those bombings, and they coincided with the Soviet invasion of Japanese-held Manchuria and an internal power struggle/near-coup in the Japanese government that eventually saw the emperor intervene (which was unprecedented). Reasonable people do disagree about what actually compelled the Japanese surrender -- you'll find much more in the FAQ.