I want to understand the extent to which scientists and technicians employed in the Manhattan project understood that they were building a bomb that would kill hundreds of thousands of people.
Wikipedia has this to say:
"An example of compartmentalization was the Manhattan Project. Personnel at Oak Ridge constructed and operated centrifuges to isolate Uranium-235 from naturally occurring uranium, but most did not know what, exactly, they were doing. Those that did know, did not know why they were doing it. Parts of the weapon were separately designed by teams who did not know how the parts interacted."
( https://en.wikipedia.org/wiki/Compartmentalization_(information_security) )
Obviously some top scientists knew that they were building a bomb. For example, I know (from hearsay) that von Neumann and Ulam (and some others?) developed Monte-Carlo methods in order to analyze when the reaction would reach a critical point, and I also know (from hearsay) that there was a general fear that Germans would build the atom bomb first. (Though it seems like this fear was unfounded.)
I'm also interested in learning about how they were propagandized. (I guess that the fear of Germans building a bomb is part of this.)
Can someone recommend some resources?