In late 1939, with a world war already ignited in Europe, there was suffi­cient high-level theory to indicate that explosives using the binding energy of atomic nuclei were possible. Weapons based on nuclear energy princi­ples had a frightening potential, with the most concern being that the opposing side would develop them first.

While solid theories made such devices seem possible, there were many details of implementation to be worked out. There were experi­ments to be run and data to be collected, and after that a massive indus­trial conversion would be necessary, going from small-scale laboratory setups to large-scale production. It was nothing that any individual, any organization, or any consortium of companies had the resources to make happen. There was too much risk of failure, even if the expense and effort were feasible. It was a problem of governmental scale, and not just any government could handle it. In this chapter, the process of awakening the U. S. government to engagement in this massive scientific research and development is examined.

The working weapon theory was that a runaway chain reaction of fis­sions could be started, but to this point no such action had been observed. It would take a large, pure sample of U-235 to perform an experiment, and the problem of purifying a rare isotope of uranium in mined ore was enormous. It would be a large waste of effort if it turned out that a chain reaction was not possible. This chapter reveals the important step of first

proving the chain reaction concept using naturally occurring concentra­tions of the fissile uranium isotope, creating a controlled, nonexplosive form of nuclear energy release.