The Manhattan Project: Making the Atomic Bomb

Reorganization of the Manhattan Engineer District

Decisions made in September provided administrative clarity and renewed the project's sense of urgency. Bush and the Army agreed that an officer other than Marshall should be given the assignment of overseeing the entire atomic project, which by now was referred to as the Manhattan Project. On September 17, the Army appointed Colonel Leslie R. Groves (promoted to Brigadier General six days later) to head the effort. Groves was an engineer with impressive credentials, including building of the Pentagon, and, most importantly, had strong administrative abilities. Within two days Groves acted to obtain the Tennessee site and secured a higher priority rating for project materials. In addition, Groves moved the Manhattan Engineer District headquarters from New York to Washington. He quickly recognized the talents of Marshall's deputy, Colonel Kenneth D. Nichols, and arranged for Nichols to work as his chief aide and troubleshooter throughout the war.

Bush, with the help and authority of Secretary of War Henry L. Stimson, setup the Military Policy Committee, including one representative each from the Army, the Navy, and the Office of Scientific Research and Development. Bush hoped that scientists would have better access to decision making in the new structure than they had enjoyed when DSM and S-1 operated as parallel but separate units. With Groves in overall command (Marshall remained as District Engineer, where his cautious nature proved useful in later decision making) and the Military Policy Committee in place (the Top Policy Group retained broad policy authority), Bush felt that early organizational deficiencies had been remedied. ²⁴

During summer and fall 1942 technical and administrative difficulties were still severe. Each of the four isotope separation processes remained under consideration, but a full-scale commitment to all four posed serious problems even with the project's high priority. When Groves took command in mid-September, he made it clear that by late 1942 decisions would be made as to which process or processes promised to produce a bomb in the shortest amount of time. The exigencies of war, Groves held, required scientists to move from laboratory research to development and production in record time. Though traditional scientific caution might be short-circuited in the process, there was no alternative if a bomb was to be built in time to be used in the current conflict. As everyone involved in the Manhattan Project soon learned, Groves never lost sight of this goal and made all his decisions accordingly.

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