The “super secret, pinpoint accurate” Norden bombsight was propaganda. We ought to know by now that it takes, from the WWII POV, "sufficiently high technology to be indistinguishable from magic" to achieve the “pickle barrel” accuracy in level high-altitude bombing of which the Roosevelt Administration boasted. Simply too much unknown, or poorly known, in the problem.Why was the propaganda important? Because American voters circa 1940 considered British-style nighttime carpet bombing to be a war crime. Thus, American daylight raids using magically accurate bombsights were a political imperative in 1944. The Dresden raid was a blatant exception - and there were American bomber pilots who protested, and had to be intimidated into complying with the orders.
FDR was bloody minded about “unconditional surrender” - which was popular with civilians, but less so with professional soldiers because it was perfect for NAZI propaganda. Churchill didn’t like it either, but he was the junior partner and bit his tongue. It certainly didn’t reduce the fanaticism with which the Germans defended the Fatherland.
In any event, it would have been FDR, not Truman, making the call. And FDR would have wanted to do whatever was good for the USSR. But even though there was reciprocal racism at work in the military relations between Japanese and Americans, I come down on the side that you couldn’t actually hold back a war-ending technology at a time when the Allies were taking casualties at a horrific rate. It would have been interesting to see how FDR would have squared the circle of absolute rejectionism of Germans vis a vis surrendering to Russians and his commitment to the Russians not to negotiate a separate peace with Germany. Even with the A-bomb . . .
For a WWII atomic bomb? Are you kidding?
The Brits resorted to nighttime bombing of Germany because they didn't have the fighter planes with the range to escort them into Germany and fight off Nazi planes. The Americans did.
Because American voters circa 1940 considered British-style nighttime carpet bombing to be a war crime.
Perhaps for pacifists, but with what the Germans were doing to London, and following Pearl Harbor, that sentimental notion quickly evaporated.
Dresden involved both British and American bombers. I've not heard of any American pilots who objected. Certainly it wasn't former Royal Air Force Marshal, Sir Arthur 'Bomber' Harris, who later said, "If I had to have the same time again I would do the same again, but I hope I wouldn’t have to."
And any alleged difference in attitudes of FDR and Harry Truman about the use of the atomic bomb can be dealt with by this quote:
“The atom bomb was no ‘great decision’… It was merely powerful weapon in the arsenal of righteousness.” – Harry S. Truman, at a Columbia University Seminar, April 28, 1959, New York City, as quoted in The Buck Stops Here: The 28 Toughest Presidential Decisions and How They Changed History, Thomas J. Craughwell, Edwin Kiester Jr., Quarry Books, 2010, p. 178.