Inexcusable intelligence failures!!
Despite the absurd fears and warnings of those "in the know", Nazi's never had an advanced nuclear program!!
Well, that's how it seems that modern journalists would cover the story, anyway.
Some applicable quotes from the above two links:
After a German and an Austrian discovered fission in 1938, almost everyone thought Germany would be the first to build nuclear weapons. In August 1939, Albert Einstein warned President Roosevelt of the threat. Dread of a Nazi A-bomb drove the Manhattan Project. Yet an Allied mission code-named Alsos, following on the heels of troops liberating Europe, found only a primitive program. No working nuclear reactor. No large quantities of separated Uranium-235, a basic bomb ingredient. No credible bomb design. "Sometimes we wondered if our government had not spent more money on our intelligence mission than the Germans spent on their whole project," wrote Alsos scientific director Samuel Goudsmit.
From as early as 1939, those "in the know" in the United States worked under the constant fear that Germany might have as much as a two-year lead in the development of a nuclear weapon. Unless and until the United States had positive knowledge to the contrary, we had to assume that the most competent German scientists and engineers were working on an atomic program with the full capacity of German industry at their disposal. Anything less would have been derelict.
The Alsos III mission entered Germany on February 24, 1945. However, now an additional urgency occupied much of their time. None of Germany's nuclear materials and absolutely none of the German scientists must be allowed to fall into Russia's hands. This new element was the source of much intrigue as the Allies advanced toward Berlin. For instance, one key German facility lay square within the planned Russian zone. There was no way that the Americans could reach the facility first so General Groves made a request to General Marshall to have it destroyed. On March 15th, 612 Flying Fortresses of the 8th Air Force dropped close to 2,000 tons of high explosives on the Auergesellschaft Works in Oranienburg just to the north of Berlin. The plant was totally destroyed.
Further intrigue ensued with a little known tactical Alsos mission labeled Operation Harborage. After France fell to the Allies, it was decided to give the French a "zone of occupation" in Germany when they finally surrendered. The zone given to the French was originally designated as an American zone. A few suspected nuclear research facilities, including the research center reputed to be in the Hechingen area was in the planned French zone. General Groves states: " As I saw it, there could be no question but that American troops must be the first to arrive at this vital installation, for it was of the utmost importance to the United States that we control the entire area that contained the German atomic energy activities...I was forced to initiate some drastic measures to accomplish our purpose."
The strategy behind Operation Harborage was to have a sizeable force, perhaps at the Corps level, cut diagonally across in front of the advancing French army and seize the area long enough to capture the people we wanted, seize and remove all available records, and destroy any remaining facilities. The operation was initiated in April 1945 and Hechingen was captured on April 24th. Col. Pash seized a large atomic physics laboratory and took into custody several sought-after scientists including Otto Hahn, Carl von Weizacker, and Max von Laue. It was learned that Heisenberg, Gerlach, and a few others had left Hechingen two weeks prior and were possibly in Munich or at Urfeld in the Bavarian Alps. On the 27th, the German scientists were transferred to Heidelberg for further questioning, where information on the whereabouts of German atomic research records were revealed by von Weizacker. They were sealed in a metal drum which was stored in a cesspool in back of von Weizacker's house.