I was just doing some thinking this morning (I know, dangerous!), after the dog woke me at 0400 and I could not get back to sleep.
You know, Hitler is responsible for nuclear weapons. (No invoking Godwin's law, please!)
Without Nazi antisemitism, the US would never have started the Manhattan Project. Not only was this dependent on refugees from Axis countries (.g. Enrico Fermi), but without Einstein's signature on the letter to the president, it would never have got funding. And without the antisemitism, he would not have been in the US.
Without the example of the US having developed nuclear weapons, and showing it could be done, the Soviets would not have done it, and France and Britain probably would not have either, as these , Britain in particular, were part of the Manhattan project and learnt a lot from it.
Germany was defeated without nuclear weapons, and Japan would have been too, although they probably shortened the war and saved lives, as the Japanese government would have needed a similar disaster to the atom bombs before surrendering - and with the allies closing in, Japan would have been subject to massive non-nuclear bombing , not restricted to two cities.
It could even be argued that if the money spent on the Manhattan Project had been spent on conventional munitions, the war may have ended earlier - for example, if the B-29 had become operational a year earlier.
