Right. I think I confused Manstein for Spiedel. Any reason why Spiedel wasn't arrested for crimes but became a Commander for NATO forces in Central Europe?
And why was Manstein spared the noose? Was Manstein's experience as a Heer commander really essential for the Bundeswehr?
Bormann either gets the noose or the firing squad.
Bormann would be hanged. They specifically denied Keitel, Göring and Jodl, who were all senior officers in the Wehrmacht, the right to be shot by firing squad, which was how soldiers were commonly executed, due to the nature of their crimes and they wouldn't grant that 'honour' to Bormann.
As for Manstein, his experience wasn't essential at all. He was a very competent commander, but not the infallible savant of warfare his memoirs painted him. And, as mentioned, he was only an advisor to the government for a while. However, 'Denazification' was in many ways cosmetic in Germany...and everyone knew it. This is not to say that West Germany was a continuation of the fascist regime. It wasn't...but there was little appetite to actually prosecute Nazis. That changed a bit during the '60s, but overall a bunch of Nazis were punished, most were left alone if they didn't cause trouble. Which is why so many Nazi war criminals, including people who'd held senior posts in Einsatzgruppen, settled down to quiet normalcy. And many doctors and other medical practitioners who were involved in T4 'euthanasia' were able to seamlessly return to medical practice.
Moreover, the 'Clean Wehrmacht' myth was basically holy writ in West Germany for a long time. The Americans let Franz Halder, who was directly complicit in the criminal orders of Operation Barbarossa but managed to whitewash himself, write a history of the war. When the Wehrmacht exhibition in 1995 detailed that the German army had also committed war crimes and been involved in the Holocaust, there was an outcry. Many people were all too inclined to believe that the boys in grey hadn't done anything wrong and had just 'done their duty' and been 'misused by Hitler and the thugs in brown and black'. After all, these were 'ordinary Germans, like us, our fathers, brothers and sons'. Actually examining the complicity of the Wehrmacht would've forced people to confront some awkward truths about that of German society. Cold War politics also played a big role. After all, these men were reliable anti-communists. Crimes that had been committed in the east were easily brushed aside. It was more convenient for many people to embrace the myth of people like Manstein being 'apolitical' professionals. This didn't only apply to the army, but also too many people in the police, judiciary and civil service, many of whom sold themselves as 'apolitical civil servants' who'd only 'remained on their post to prevent worse from happening'.
Hell, Georg Leibbrandt, who participated in the Wannsee Conference as a representative of the Reich Ministry for the Occupied Eastern Territories and thus the civic administration in the occupied Soviet territories, served as an advisor to Chancellor Konrad Adenauer in regards to the repatriation of German POWs from the Soviet Union. Here it is pertine to note that Adenauer's right hand man Hans Globke was directly involved in formulating and codifying anti-Jewish legislation and was likely involved in deportations during the war.
In regards to Speidel, he was involved in the 20 July plot, though not a major player. So that obviously helped his reputation a lot. It has been alleged that he framed Rommel, who had been his boss and actually wasn't involved in the coup, under Gestapo interrogation but as far as I know that's never been proven. That said, he eventually had to give up his post in NATO. De Gaulle really disliked him due to Speidel's involvement in 'reprisals' against in Paris. Basically, the German military command carried out executions and deportations of Jews and resistance members. Speidel, who was chief of staff for the German military commander (first that was Otto von Stülpnagel, then after his resignation Carl-Heinrich von Stülpnagel), doesn't appear to have ordered the reprisals himself, but supported and justified them as 'legitimate retaliation against Jewish communists'.
Now Speidel didn't have as much blood on his hands as say Manstein, Hoepner or Reichenau, who were all very enthusiastic about the 'racial war of annihilation', and he did come to oppose the regime, though he also had the 'good fortune' to spend much of his career in the west (he served on the eastern front for a while as chief of staff of a corps and later of an army, but I don't know anything about his record during that time.).