Editing Manhattan Project (section)

=== Manhattan District ===
The [[Chief of Engineers]], Major General [[Eugene Reybold]], selected Colonel [[James C. Marshall]] to head the Army's part of the project in June 1942. Marshall created a liaison office in Washington, D.C., but established his temporary headquarters at [[Tower 270|270 Broadway]] in New York, where he could draw on administrative support from the Corps of Engineers' [[North Atlantic Division]]. It was close to the Manhattan office of [[Stone & Webster]], the principal project contractor, and to Columbia University. He had permission to draw on his former command, the Syracuse District, for staff, and he started with [[Lieutenant Colonel (United States)|Lieutenant Colonel]] [[Kenneth Nichols]], who became his deputy.<ref name="NYT">{{cite news |last=Broad |first=William J. |url=https://www.nytimes.com/2007/10/30/science/30manh.html |title=Why They Called It the Manhattan Project |newspaper=[[The New York Times]] |date=30 October 2007 |access-date=27 October 2010}}</ref><ref name="Jones, pp. 41-44">{{harvnb|Jones|1985|pp=41–44}}.</ref>

[[File:Manhttan Project Organization Chart.gif|thumb|The Manhattan Project Organizational Chart, 1 May 1946|alt=Organization chart of the project, showing project headquarters divisions at the top, Manhattan District in the middle, and field offices at the bottom]]
Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General [[Thomas M. Robins]], and his deputy, Colonel [[Leslie Groves]]. Reybold, Somervell, and Styer decided to call the project "Development of Substitute Materials", but Groves felt that this would draw attention. Since engineer districts normally carried the name of the city where they were located, Marshall and Groves agreed to name the Army's component the Manhattan District; Reybold officially created this district on 13 August. Informally, it was known as the Manhattan Engineer District, or MED. Unlike other districts, it had no geographic boundaries, and Marshall had the authority of a division engineer. Development of Substitute Materials remained as the official codename of the project as a whole but was supplanted over time by "Manhattan".<ref name="Jones, pp. 41-44" />{{sfn|Sullivan|2016|pp=86–87}}

Marshall later conceded that, "I had never heard of atomic fission but I did know that you could not build much of a plant, much less four of them for $90&nbsp;million."<ref>{{harvnb|Fine|Remington|1972|p=652}}.</ref> A single [[trinitrotoluene|TNT]] plant that Nichols had recently built in Pennsylvania had cost $128&nbsp;million.<ref>{{harvnb|Nichols|1987|p=174}}.</ref> Nor were they impressed with estimates to the nearest order of magnitude, which Groves compared with telling a caterer to prepare for between ten and a thousand guests.<ref>{{harvnb|Groves|1962|p=40}}.</ref> A [[surveying|survey team]] from Stone & Webster had already scouted a site for the production plants. The [[War Production Board]] recommended sites around [[Knoxville, Tennessee]], an isolated area where the [[Tennessee Valley Authority]] could supply ample electric power and the rivers could provide cooling water for the reactors. After examining several sites, the survey team selected one near [[Elza, Tennessee]]. Conant advised that it be acquired at once, Styer agreed, but Marshall temporized, awaiting the results of Conant's reactor experiments.<ref>{{harvnb|Hewlett|Anderson|1962|pp=76–78}}.</ref> Of the prospective processes, only Lawrence's electromagnetic separation appeared sufficiently advanced for construction to commence.<ref>{{harvnb|Fine|Remington|1972|p=654}}.</ref>

Marshall and Nichols began assembling the necessary resources. The first step was to obtain a high priority rating for the project. The top ratings were AA-1 through AA-4 in descending order, although there was a special AAA rating reserved for emergencies. Ratings AA-1 and AA-2 were for essential weapons and equipment, so Colonel [[Lucius D. Clay]], the deputy chief of staff at Services and Supply for requirements and resources, felt that the highest rating he could assign was AA-3, although he was willing to provide a AAA rating on request for critical materials if the need arose.<ref>{{harvnb|Jones|1985|pp=57–61}}.</ref> Nichols and Marshall were disappointed; AA-3 was the same priority as Nichols' TNT plant in Pennsylvania.<ref name="Fine 1972 657">{{harvnb|Fine|Remington|1972|p=657}}.</ref>