No, Hiroshima was pretty unambiguous. Nagasaki is a bit of a stretch, but you have to be pretty revisionist in your view of history and the state of the world in '45 to doubt its necessity (we have one, it works, and we can deliver it) vs. the second (we have more than one, capitulate or die in flames...)
Neither Hiroshima nor Nagasaki had any effect on the Japanese leadership of the time, as minutes of government meetings show. The nuclear attacks paled in comparison to the firebombings or larger cities such as Tokyo.
What ended the war was Soviet invasion. Apparently Japan would rather surrender to the USA than face a post-war country divided on two fronts as Germany was.
Agreed would any sane president look at the generals projected 98% wastage rate for the first 5 waves ashore for operation Olympic and think well this new weapon could force a surrender but no I will give America her own Verdun or Somme what's 1/2 a million dead GI's and Squaddie's.
Of course, a bat bomb wasn't a sure thing, but Fat man was much more complex than little boy, which wasn't as efficient, and we didn't have much more nuclear material than a few bombs worth at the time.
So, in hindsight, I don't think it's easy to say whether or not the atom bomb was absolutely necessary to ultimately prevent many lives (on both sides) from being lost. I do believe it was very effective to that end, however, with the side effect of letting the nuclear genie out of the bottle.
That weapon is so weird. So incredibly weird. Just what you'd expect from a Pennsylvania dentist-cum-weapons researcher, I guess? Thanks for pointing it out!
Hiroshima was only necessary if it was the only way to get Japan to capitulate. This ignores rumours of back-channel diplomatic dealing that could have seen through a less humiliating exit for Japan.
The entire point of unconditional surrender was to humiliate Germany and Japan for starting the largest war yet known to man, leading to the deaths of tens of millions of human beings.
