Did U.S. Have to Drop Atomic Bombs on Hiroshima and Nagasaki?

Nobody really knew what an "atomic bomb" could or would do until the Trinity test. Remember as the clock counted down to detonation there were bets taken among the technicians in the control bunker (who probably had more realistic ideas than almost anybody) on what was going to happen, and the answers ranged from 'complete fizzle' to 'a couple dozen tons of TNT' to 'ignite the atmosphere of the planet and destroy all life on Earth.'

I'm sure Hitler had some experts urging full-throttle development of an A-bomb and some others claiming it would be a complete waste of money and available resources. As you noted I think it was a key factor that several of the key scientists needed in the effort had already defected to the U.S.

Developing the bomb was a long unpredictable process: it wasn't like Roosevelt decided in mid-1942, "hey, let's get us some A-bombs; let's order delivery in July 1945." They didn't know if it was going to take 2 years, 3 years, or 10 years to develop it.

 

In all the movies and books I have read, an elite team of American heroes, with at least one plucky type from the Bronx and a Brit thrown in for diversty, snuck into Germany and blew up Hitler's secret bomb-building lab.

 

Seeing what you did there, but I believe there actually was a famous air raid on an installation in Norway that is credited with severely damaging the Nazis' efforts.
Don't have time to look it up this second, but I remember seeing a documentary about it on the History Channel. I think it was a heavy water plant.
The Brits used a keg-shaped bomb to blow up a dam that was powering the place. Conventional air raids hadn't worked, so they designed the kegonator to skip across the water and blow up when it hit the dam.

 

That's pretty cool. Like to see that. I do recall that hitting the heavy water plant was a thing.

 

Like I said, I watch NOVA: NOVA | Hitler's Sunken Secret | PBS

 

I don't think there is much or any doubt Hitler would have ordered the instantaneous use of the A-bomb against any and all of his adversaries the moment Germany would have developed it. There wouldn't have been 10 seconds' delay.

The Japanese military leaders would have been just as eager, maybe more; for a tiny isolated island nation facing adversaries which controlled the resources and manpower of entire continents (U.S., U.S.S.R.), it would have been the great equalizer.

 

And... spoiler alert!

NARRATOR: The Hydro was carrying far too little heavy water for even one reactor, let alone the 10 or more that would have been needed to make enough plutonium for a nuclear weapon. So, were the Allies right in their belief that the heavy water was destined for a bomb project? Did the Germans in fact want it for some other purpose?

Within a few months of the sinking of the Hydro in 1944, Allied armies were advancing across Europe. Following closely behind the frontline troops was a secret operation, code named Alsos. Its mission was to find the Nazi nuclear weapons program the Allies were sure must exist.

For months, Alsos scoured newly-liberated Europe and found nothing. Then, just days before the final German surrender, they came to Haigerloch, a small town in Bavaria. Beneath a church there was a cave, and inside they found the intended destination of the Norwegian heavy water: a makeshift laboratory with a single experimental reactor that German scientists still had not gotten to work.

The Nazi nuclear bomb, which had inspired so much fear, turned out to be a mirage. There was no German equivalent of the vast Manhattan Project.

The reason, believes historian Mark Walker, can be found in a decision made in early 1942, just at the time when the Allies were also deciding whether to embark on the Manhattan Project.

MARK WALKER: In early 1942, precisely when the Allies are getting concerned about Norwegian heavy water, American officials and German officials make crucial decisions about their nuclear weapons projects. Interestingly, scientists in both countries said the same thing; the scientific results were essentially the same. Scientists in both countries said, it'll take a couple of years, but nuclear weapons are possible. Now, in America it was assumed that the war was going to take a long time: "These weapons will be done before the end of the war, therefore we have to try to make them." In Germany it was assumed that: "If we don't win the war quickly, we will lose; these weapons might be interesting for the future, but they're no help to us now. It would be a waste of energy, money, and time to try to make them."

NARRATOR: So German nuclear research was transferred to civilian control. The Hydro shipment was destined for an experimental reactor project. It was of no military significance, which is why it was only lightly guarded. So it seems that the doubts the Norwegian resistance expressed about the value of sinking the Hydro were justified. Had Allied intelligence known what we know today, they might well have agreed that the shipment was not worth stopping.

 

Yeah, the bomb took a long time to develop and there were a long list of things that could have forced it to take longer to actually make. Because of just how long it took to figure out the whole question of critical mass and how to actually ignite the reaction (plus the small matter of enriching enough fissionable material to pull off the bomb), even if Hitler was 100 percent gung ho about it, he probably would have run out of time. And further to your point, the fact that the bomb was developed to use against Germany and not used on that country was fully because by the time we had the bomb, Germany was basically defeated.

I remember seeing the kegonator (love that term) story on the History Chanel. I think Batman is right (along with other factors including losing key scientists), the loss of the heavy water plant played a significant role in derailing the German atomic program.

 

The bomb dropped on Hiroshima was a type that had already been determined to be obsolete. It used U-235 as its fissile material, of which you need a helluva lot to make a bomb. Further, that type of bomb isn't all that efficient.

The bomb dropped on Nagasaki, which used implosion of Pu-239, was the type that was tested in New Mexico (the Hiroshima bomb was never tested).

 

Are you sure those barrel bombs were aimed at heavy water plants? I thought they were designed to blow up dams.

 

Correct, they only had enough enriched uranium for one bomb.

 

All of Wehrner's rockets blew up until they put that chimp in one in 1961