Manhattan Project
World War II American R&D program that produced the first nuclear weapons
The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. The Manhattan Project employed nearly 130,000 people at its peak and cost nearly US$2 billion (equivalent to about $28 billion in 2024).
From 1942 to 1946, the project was directed by Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the bombs. The Army program was designated the Manhattan District, as its first headquarters were in Manhattan; the name superseded the initial codename, Development of Substitute Materials, for the entire project. The project absorbed its earlier British counterpart, Tube Alloys.
Over 80 percent of project cost was for building and operating the fissile material production plants. The project proposed both highly enriched uranium and plutonium as fuel for nuclear weapons. Enriched uranium was produced at the Clinton Engineer Works in Tennessee.
Begin with the source’s own compact description: “Manhattan Project” is world War II American R&D program that produced the first nuclear weapons. The dossier treats that line as a proposition to test through Manhattan, Project and World, not as a finished interpretation.
Why this record matters
The phrase “world War II American R&D program that produced the first nuclear weapons” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Contemporary correspondence, administrative files and participant testimony can test how later narratives organized the event or institution. The source revision retrieved here is dated Sep 23, 2026. The linked authority identifier is Q127050. VIAF identifies the subject as 124438256. The Library of Congress control number is n88074979. None of the 2 selected statements returned an explicit reference. The first chronological checks are 2024, 1942 and 1946.
Institutional narratives can privilege the records that survived while minimizing voices that were never formally collected. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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Three-step research path
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This entry incorporates text from “Manhattan Project” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.