Heisenberg
Wasn't ever core (ahem) to the German uranium project which was run mainly by Kurt Diebner. Early on the Germans had decided to concentrate on the power generation potential of fission rather than the bomb, so the Norsk Hydro heavy water was absolutely key to their objectives in calculating the fissionability of uranium.
Fortunately for us the whole project never got a very high profile in the Reich (Speer reported that Hitler only showed a passing interest in the subject) and for a long time ended up being funded by the Reich Postal Ministry of all places. By the time the Germans got round to experimenting with uranium enrichment they were being bombed back to the stone age and there was a crippling shortage of key components.
The German uranium project was eventually wrapped up by the Allies as Operation Alsos (alsos - 'grove' in Greek. The Manhattan Project was run by General Leslie Grove). They recovered a near-criticality experiment and several tonnes of uranium, but nothing close to what the Americans, British and Canadians had achieved.
Oh and trivia buffs. The Joachimsthaler mines which provided the Germans with their uranium were the only source of the metal in Europe. They had also provided Marie Curie with the pitchblende in which she discovered radium and polonium. Uranium extraction had been a side effect of mining silver. Which was used in the local currency, called the thaler. Whose name lives on as 'the dollar'.
Richard Rhodes' 'The Making of the Atomic Bomb' is absolutely recommended reading for anyone interested in how we came to be where we are today.


