It never ceases to amaze me that demonstrating such a weapon on civilian targets somehow made it past the entire chain of command. One of those things that I just can't wrap my head around no matter how many times I come back to it.
The sites in question were also specifically selected because they hadn't previously faced conventional attack, enabling a more accurate damage assessment.
Which, by the way, illustrates a related point: Hiroshima and Nagasaki had stiff competition. WWII was devastating, to cities and civilians all over the map. More people died in the conventional bombing of Tokyo than the atomic bombing of Hiroshima. I think the atomic bombs represented some 2 weeks worth of casualties in a war that lasted 300.
