The authorization for the construction of facilities dedicated to the 'Development of Substitute Materials,' which would evolve into the Manhattan Project, occurred under the leadership of Major General Eugene Reybold. This move formalized the United States’ commitment to developing atomic weapons in response to the advancements made by Axis powers, particularly Nazi Germany. The project was tightly integrated with the country's wartime priorities, aiming to harness nuclear fission for military purposes.

In the coming months, the project would see significant investments in specialized laboratories, manufacturing plants, and research networks. Key locations included Oak Ridge, Tennessee; Los Alamos, New Mexico; and Hanford, Washington, where cutting-edge research and technology would lead to the enrichment of uranium and the creation of plutonium. The scale of secrecy surrounding the project underscored its importance as a potential game-changer in the ongoing conflict of World War II.

The facilities were not only intended for developing substitutes for fissile material but also for conducting extensive tests and experiments. This led to unprecedented collaboration among physicists, engineers, and military personnel, showcasing the intersection of science and military goals. The authorization represented a pivotal moment in U.S. military policy and scientific pursuit, indicating a significant shift toward utilizing advanced technology for combat effectiveness.