I'm just going to address a few points here that I found humorous.
The entire argument boils down to the simple "the ends justifies the means". The application of this sort of morality is that everything is allowed. As a logical argument it;s pretty shallow. The deliberate killing of civilians is a war crime
War is one of the most immoral actions humans can undertake, so attaching morality to it is meaningless. War crimes do not exist - they are merely a tool by the victor to cement their victory in the minds of the defeated, and of their own countrymen.
Maybe the atomic bomb did "save" allied lives
The atomic bomb, without a doubt, did save American lives - which in the end is the only thing the American military command needs to worry about. Even one American death, when it was possible to end the war with none, would be too much in this case.
I believe the reason for the second bomb was that we believed that the Japanese might have been under the misconception that such a massive bomb had to be some sort of singular, unrepeatable achievement
The reason for the second bomb was two-fold. The first was to convince the Japanese Emperor to surrender, rather than the military high command which would fight to the last man. The last was in response to the Soviet invasion of Manchuria, to both warn them, and try to hurry a surrender so as to leave them out of the peace negotiations.
10s of thousands of innocent lives.
Okinawa had demonstrated that there were no innocents in Japan. These so-called civilians were more than willing to engage American military personnel in kamikaze attacks, at the behest of their Emperor, and the Japanese military. Another fact is that industrial warfare has changed the definition of innocents. Any man, woman, or child can be handed a rifle and told to fire in a general direction. Any man, woman, or child, can work in a factory to build bullets used to kill the enemy. Industrial war is, unfortunately, total war.
This all being said, the atomic bombs were perhaps unnecessary. The Japanese were willing to surrender, though not unconditionnally, as early as June. One of my favorite quotes is by the Emperor himself:
I was told that the iron from bomb fragments dropped by the enemy was being used to make shovels. This confirmed my opinion that we were no longer in a position to continue the war. It is well known that the Japanese tried to negotiate a peace through the Soviet Union and failed to do so. The first, and perhaps largest reason is that the Allies simply refused a conditional surrender, following the Potsdam Declaration. A second reason is that the Soviet Union did not act in good faith, because it stood to benefit from a continued war against an enemy who could not win. Stalin specifically had plans to seize Manchuria, and needed time to move his men from the west to the east. The Emperor in fact, on August 9th, said:
The Soviet Union has entered the war, we are defeated.My opinion is that the failure of the Japanese defense forces to ready their foritifications, domestic disputes, and the Soviet invasion were the primary reasons for the Japanese surrender, with the atomic bombs merely hurrying it along. In this thesis, the atomic bombs were not necessary - but did save time, and thus lives.