I think some of you overestimate the effect of a nuclear weapon. It's nowhere near such a doomsday device as has been suggested in some posts.
The roughly two dozen nuclear bombs fired in the war would neither lead to a nuclear winter nor any other noticeable
direct disruption of the affected nation's agriculture and population besides the immedeate areas affected by the blast wave and the fall-out.
Even in the worst case, this would be confined strictly to a small area in the bombed HoI2-province.
Also, only bombs exploded on the ground will create large-scale fall-out, so it is extremely unlikely that every single warhead contaminated large areas of land. In fact, a nuclear airburst is more destructive than its counterpart since it distributes its energy more evenly and over a wider area than a weapon detonated at surface level, so it would be favoured by the targeteers of this timeline, especially since nuclear fallout and the damage it can do weren't really known at that time. I'd estimate that the only fallout experienced in this timeline was the result of weapon-malfunctions and nuclear tests.
Furthermore, even if areas got contaminated, the radiation levels will decline sharply within a few days and the danger from fallout will be practically nonexistant within 3-5 weeks. So there won't be any areas of forever inhospitable green-glowing countryside either, agriculture can resume the next season (especially if there is a desperate need for food).
However,
indirect effects such as flight into the countryside out of fear of further attacks, collapse of public and military infrastructure branches, etc, could be quite severe and constitute an overwhelming part of the damage done to the attacked nation, which would get escalatingly worse the more often a nation is hit. That's why the third world war would have been so destructive, besides the staggering number of warheads involved, of course.
In this timeline, however, only a few bombs were fired and the only nation in danger of such a collapse would be Britain. For Germany, the destruction caused by conventional warfare likely far outstrips the damage done by the nuclear bombs and the population perhaps sees the bombs as just another weapon equivalent to an excessive conventional bombing raid.
There is also really no reason why a city hit by a nuclear attack has to be abandonded and cannot under any circumstances be rebuilt. Remember, both Hiroshima and Nagasaki still exist today as large cities. German and Japanese cities hit by Allied bombing raids, which in some cases did cause similair amounts of destruction such as in Dresden, also all were rebuilt.
The only thing which would keep a nation from reconstruction efforts would be an ongoing war, so it makes sense for the US to seek a new power-base, while nations like Nazi Germany and Britain, which were dominated administratively and culturally by their capitals, would likely have returned there by now and started rebuilding. In this timeline, they were victorious after all and rebuilding their capital bigger and better than before would likely be an important symbolic gesture for them.
Also, the Nazis planned to completely erase Berlin and rebuilt it from scratch as their new world capital anyway.
As to the casualty figures: Those figures are way to high, you are assuming that the entire city population just waited for the nuclear attacks to occur without preparing in any way, standing outdoors and likely congregating in the city centers to make sure they'll die.
Even if we assume that nobody fled to the countryside during the several months over which the nuclear exchange took place (for example, even during the relatively harmless Battle of Britain many people did just that), basic bomb shelters would reduce the number of deaths siginificantly. During the Second World War, civil defense was taken more seriously than the later duck&cover-approach. I'd at least quarter those casualty figures.
@frigidmagi:
You are basically starting with the worst-case assumption for Germany, while I argued from a best-case scenario, so I see where the difference in tone comes from.
Well, it all depends on interpreation, but still I think you are way too drastic here. 30% civilian casualties is completely unheard of even in such a dystopian scenario. That's what, 20 million dead? You are assuming that every civilian stayed put in his home during a Stalingrad-like battle spanning all of Germany. That seems unlikely in the extreme and isn't what I would call realistic modelling.
During the real Sowjet advance, a massive wave of fugitives heading west swamped Germany. That of course creates problems all of its own. Still, the allied advance was way slower than the Sowjets and it took them months to take even one province. The fronts were that static. I'll restate my opninion: Everyone who didn't want to be occupied could have walked away even if there wasn't any planned evacuation.
What happened to those people after they passed the Oder river is another matter. They sure as hell don't lead the happy lives promised to them in Lebensraum-propaganda, but the German military presence during the war would also have prevented any successful resistance. I think Firestorm is quite correct in predicting mass starvation across the world.
Furthermore, the allies held no air superiority in this campaign. In fact, Firestorm eventually lost his entire air force during the height of the battle for Germany. So there weren't any bombing raids to harass the German transportation network.
I'll try to return to my point.
You are entirely right when you say that Germany really has no interest in continuing the war, all its objecitves are achieved. On the list of problems Germany has, the US wouldn't even surface in the Top 10.
However, unluckily for America, on the list of credible opponents that could put up a fight, the US wouldn't make the Top 10 either. All it would take to topple the US at this point is landing one army of perhaps 9 divisions in America in support of one of the revolting states. 9 division out of several hundred just standing around and digging in in Europe while the Sovjets are still busy in Asia.
So it's true that Germany doesn't really want to concern itself with American affairs, but it is equally true that Germany could crush the US just as easily as if it were swatting an annoying fly and that's the reason why I consider it foolish to continue to abuse Germany in propaganda messages.
Why provoke the sole supwerpower on the planet when you could for example use the Commie threat? After all, they basically backstabbed the US during the war and also support some of the civil war factions.
And here we roll into the next bit. One I have established that Germany frankly isn't going to war with the US at this point. This means there is no real not to speak badly of Nazi Germany. Besides which nations do not tend to go to war over folks speaking badly of them. Has the United States bombed Iran for calling it the Great Satan? Has China done anything to the US over all the nasty things said about it over here? Or the on going bits in both the US and Russia about each other? A series of radio broadcasts where an American says unkind things won't start a war.
Don't make the mistake of dismissing propganda press releases as diplomatically insignificant. Especially during the time of WW2 great effort was put into ensuring that propaganda releases didn't anger the wrong people. Think about how every criticism of the Sovjets was suppressed. At the same time Germany tried to remain in good favor with the British population by always honouring the British soldier's efforts in the war and only condemning their leadership.
And this hasn't really changed since then. If today a politician endorsed a controversial right or left wing media platform angering another nation, you can be sure that there would be a diplomatic aftermath.
As for examples of nations going to war because someone spoke badly of them:
The Franco-Prussian war for one.
A war won't erupt because of bad press alone, however, but bad press can be used as a pretext to declare war.
Not unless it's backed up with action and the US bluntly can't back it up. So why worry? Frankly the German government is unlikely to give a shit, at least not until after the civil war is over.
The US can't back up it's retoric, but what if Germany want's to wipe the US from the map as long as it is still barely able to defend itself against revolting states?