Hitler's Nuclear Bomb Program
In 1938, German scientists discovered nuclear fission. It was in the headlines in scientific circles in the USA, England and elsewhere, yet, not in Germany. The announcement of splitting atoms and what that potentially meant was studied by the USA and England along with the German scientists during this pre-war event. Most of the Hitler's organizations knew nothing about it or cared. It was not until 1939, that the first real announcement in the German scientific community appeared. That got the interest of the German Ministry of Ordnance seeking to procure new weapons. Yet, the interest was of curiosity and few resources were ever devoted to it when compared to investing in jet aircraft, rockets. While the German scientists knew it could be done and a nuclear reactor built, the soonest this could be accomplished with full resources and manpower might be by 1943, at best. This would be just to make a nuclear reactor prototype, not a nuclear bomb. While the Ordnance Ministry knew of the discovery and possibility, Hitler was not even told of it until 1942. While nuclear fission was discovered in 1938, it was not until 1941, did the Germans and Americans realize a nuclear bomb could be built. In any case, enough interest in 1940 existed to seize the Norsk Hydro Plant in Norway and double the production of "heavy water" required of a nuclear reactor. This production was crippled by a British SAS raid in 1943.
Hitler wanted any new weapons to be developed and available within six months. Generally, this could be done and rockets like the V1-V2 were allowed to continue for a year. So, the development of a German nuclear bomb simply could not be done within that time frame with so meager resources devoted to it and the lack of necessary material. On the contrary, the USA devoted full resources to develop a bomb starting in 1941. In 1943, the war for Germany began to fail and Hitler's attention about weapons that "might" occur with long development times were very low on his approval list. He simply would not approve funding for such a project because more promising weapons could be used much sooner.
The Germans actually did make a small scale nuclear reactor for study and testing. Built in Haigerloch, in southwest Germany, the reactor was located in the basement of the Schwanen Inn, well protected by rock. The aluminum container had a diameter of 210 cm and a height of 210 cm, and contained another vessel made of magnesium weighing 10 tons. It used 664 blocks of uranium and experiments began in late March, 1945. It was estimated that for a "real" full scale reactor, the size would have to be 1.5 times the size. When the US troops found the site, they were ordered to blow it up but because it was located below a church, it was not. It was taken apart. US troops found two million tons of uranium blocks.
Ironically, both German and American scientists knew much of the physics required to build a nuclear reactor to create plutonium for a nuclear bomb in 1940-1, the difference was that there was just a "passing" interest in this for Hitler and others, while in England and America, full resources and a top priority was given to it. Thus, when America used the bomb on Japan in 1945, most of the leading German scientists in nuclear fission were shocked.