The story of the production of fissionable materials at Los Alamos is about the challenges of working with little-known, scarce substances under difficult experimental conditions, as well as the excitement of discoveries and unexpected turns in the course of all-out efforts to achieve practical results quickly. The interplay between the plutonium and uranium efforts within CM-Division reflects the wartime strategy of pairing complicated and straightforward tasks. In this way, personnel, equipment, and time could be focused on the most demanding problems. Thus, the relatively simple effort to produce uranium gun parts at Los Alamos complemented the more difficult effort to produce plutonium spheres, just as the relatively simpler gun program as a whole later complemented the more complex implosion program. Those implementing the less intricate effort were under pressure to proceed rapidly and produce absolutely reliable results meeting all contingencies so that more of the group's resources could be diverted to the thornier problem. Consequently, the uranium program was remarkably fast-paced and rigorous. The need to make the most of resources and save time weighed especially on Joseph Kennedy, Arthur Wahl, and Cyril Stanley Smith in CM-Division, because they had to adjust to the changing requirements of the other divisions, for whom they provided support services, while at the same time working to achieve their own goals.