Obviously something like this was unprecedented at the time. What was the response of the Allies and other outside parties to this event?
I'm very sorry that I can't find a previous answer. The question was written under "AskHistorians Podcast 068 - Hiroshima, Nagasaki, and Restricted Data". But at that time, in August 2016, /u/restricteddata did not know of a good comprehensive study, and he's done quite a lot of research and writing about nuclear weapons.
This is not to discourage discussion, especially as there has been little! More questions, data and debate are welcome.