Having made the bombs, I think they were used correctly, but I kind of wonder if the whole Manhattan project was a waste of resources better used elsewhere. We spent tons of money, resources, brain power, etc on their development, and most of the time since we have had them, they have been more of a threat to us, than a threat we could use. Would it have been better to have spent all those resources on developing jets, (Which came in early 45) rockets, ships, tanks etc? Since we sent all that resource into researching the bomb, we had an opportunity cost on other ways we could have used the resources. Things that might have produced better results sooner. It would have been cooler if we could have moved into France a year earlier, and all the personell in New Mexico could have been producing materials to do that. And the painful reality about any tech is that it is easily copyable once you know it works and what the ingredients are. Despite a lack of materials, the Russians were able to do a bomb in 1949, large portions of the research based on US materials. Had we concentrated on other projects, the Russians, for internal political reasons, probably would not have bothered either. The main goad for the Manhattan project was that the Germans seemed well on their way. It was a German attempt to refute the work of Fermi that led them to replicate one of his experiments. Fermi, not being a chemist, didn't know what he had done, but the Germans went one step beyond and explained what Fermi's experiment did. Fermi's next experiment would have been better as a power source design rather than a bomb design. Building bombs with nuclear energy seems to have been a waste, it would have been cooler if Femi had gone the next step and said "Gee, we could power ships with this tech!" rather than "Lets see if we can make it go boom"