Given the secrecy surrounding the bombs, it is highly likely that not one of them had any idea what it was they were assembling/loading into the plane. All they likely knew was that it was "some kind of new, secret, bomb". It is questionable whether the "high ranking officials" referenced in the plane alignment photo caption even had much knowledge of just what this "new, secret, bomb" really was.
I think most of them had an idea about atomic bombs back then, and what they were doing could end the war. Robert Heinlien was investigated by the FBI in the late 30's due to a description of atomic bombs in a story he'd written. So the idea was out there so to speack.
What they were ignorant of, I'm pretty sure, was the actual magnitude of the destruction caused by the devices. My father was about 10 yrs old at the time, he was deeply effected by news reels at the time. The tragedy was horrific.
The atomic bombs were not more devastating to Hiroshima and Nagasaki than were conventional bomb campaigns to other similar cities in Japan toward the end of World War II. The damage from atomic bombs did not stand out as extraordinary to the Japanese leadership at the time. What forced Japan to surrender was Russia's declaration of war. http://www.foreignpolicy.com/articles/2013/05/29/the_bomb_di...
" ... But if you graph the number of people killed in all 68 cities bombed in the summer of 1945, you find that Hiroshima was second in terms of civilian deaths. If you chart the number of square miles destroyed, you find that Hiroshima was fourth. If you chart the percentage of the city destroyed, Hiroshima was 17th. Hiroshima was clearly within the parameters of the conventional attacks carried out that summer. ..."
Now chart out the number of planes used in the attack and the potential rate of attacks once the production pipeline really got going. That's what made it remarkable. A thousand B-29s fly over your city and leave it a smoking ruin is Tuesday, but two B-29s fly over and do the same and that's something new and scary.
Contrary to your statement that the attack was considered unremarkable, reports of the attack were initially disbelieved by the Japanese government because they knew of nothing that had occurred that could have caused such damage: "It was generally felt at Headquarters that nothing serious had taken place, that it was all a terrible rumor starting from a few sparks of truth."
The ultimate effect of the atomic bombings on the surrender compared to the Soviet intervention is highly debatable, of course, but it wasn't irrelevant just because it wasn't the most devastating attack of the war.
Its more like saying that a single bomb that kills 500 is on par with an attack by an army in which 500 are shot dead.
I agree with that idea. Apart from the fact that they were single-plane attacks, there was little that set the Hiroshima and Nagasaki bombings apart from what happened to almost every city in Japan. Yes, radiation sickness is awful, but so are napalm burns on half your skin.
One thing that I wonder about whenever this subject comes up is whether it would have been cheaper to deploy use conventional bombs against those targets. It would have been fairly easy to send a thousand bombers with conventional payloads (or just 200 that made 5 sorties each)
