 "Two aerial photos of atomic bomb mushroom clouds, over two Japanese cities in 1945 Wikipedia")
The Manhattan Project, the codename for a US government research project between 1942 and 1945, led to the creation of the world’s first nuclear weapons and the atomic bomb. It was conducted during World War II and received support from USA’s allies, Canada and the United Kingdom. Here is everything you need to know about the project.
Although the official codename for the project was ‘ Development of Substitute Materials’, ‘Manhattan Project’ became more popularly used. It referred to the headquarters of the initiative that was based in the Manhattan borough of New York in the United States.
The project was operational from June 18, 1942, and concluded on August 25, 1947, according to history and heritage records kept by various US government agencies.
At its height, the project reportedly employed 130,000 people across the United States.
The project cost $2 billion at the time, which would be more than $33 billion in 2023 according to inflation calculators.
Einstein’s letter to Roosevelt
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Although the project would not officially form till around three years into World War II, its initiative can be traced back to 1938-39. Many historians cite this as the actual year for the beginning of the Manhattan Project when German physicists Otto Hahn and Fritz Strassman discovered nuclear fission in December 1938.
In August 1939, Albert Einstein wrote a letter to US President Franklin Delano Roosevelt regarding research on fission chain reactions that utilised uranium. This made it possible to harness large amounts of power that had the potential to create an “extremely powerful bomb.”
Einstein drafted this letter with the help of Hungarian émigré physicists Leo Szilard and Eugene Wigner, urging the US government to support research in this area, as he believed the German government was doing the same at the time.
Einstein, Szilard, and Wigner were among the many European scientists who fled to the US to escape the Nazi regime in the 1930s.
Roosevelt’s decision to set up a committee of civilian and military representatives to study uranium in 1939 was the first step that led to the creation of the Manhattan Project.
On December 7 1941, the US declared war on Japan which had bombed Pearl Harbour. Three days later the US officially entered the world war after declaring war on Germany. President Roosevelt approved the creation of an atomic bomb the following month on January 19, 1942.
The Army Corps of Engineers Manhattan District was subsequently established on June 18, 1942.
Oppenheimer’s role
American physicist J. Robert Oppenheimer led the project with Edward Teller and many other scientists, significantly those who had fled Europe to escape the Nazi and other fascist regimes.
Leo Szilard and Enrico Fermi successfully built the first nuclear reactor.
Ernest Orlando Lawrence oversaw the development of uranium-235 separation using the electromagnetic process.
Other notable contributors included Otto Frisch, Niels Bohr, Felix Bloch, James Franck, Emilio Segre, Klaus Fuchs, Hans Bethe, and John von Neumann. Brig Gen Leslie R Groves served as the project's coordinator.
Einstein never worked on the Manhattan project
Einstein was considered a security risk due to his left-leaning political views. In July 1940, Einstein was denied security clearance by the US Army Intelligence Office to work on the Manhattan Project. Moreover, the scientists working on the project were prohibited from consulting with Einstein regarding the project.
His famous equation E=mc^2 is used to explain the effect of the bomb but does not provide information on how to build one.
Einstein's letter to the US President in 1939 and this equation have often wrongfully associated the scientist with the project and subsequent bombing.
According to the American Museum of Natural History, when asked about his role in the project, Einstein told Newsweek magazine, "Had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing."
Manhattan Project achievements
While the Manhattan Project's primary objective was the creation of the first atomic bomb, multiple research avenues were also explored.
Scientists developed electromagnetic and fusion methods to separate uranium-235 from uranium-238 at Oak Ridge in Tennessee. Plutonium-239 production, initially achieved in Chicago, was further pursued at the Hanford Engineer Works in Washington.
Simultaneously, researchers at Los Alamos, New Mexico, focused on achieving critical mass and designing a weapon to contain the fissionable material. The successful Trinity test on July 16, 1945, was a significant milestone for the project.
The bombing of Hiroshima and Nagasaki
Despite opposition from some scientists, then-President Harry S Truman believed that using atomic bombs could prompt Japan's surrender and avoid an American invasion.
On August 6, 1945, an atomic bomb was dropped on Hiroshima, instantly claiming tens of thousands of lives and leading to long-term radiation-related casualties.
Three days later, Nagasaki suffered a similar fate.
Post-bombing, Project disbanded
The bombings of the two Japanese cities fueled a belief among nations that possessing nuclear arms ensured their safety, despite concerns about the increased risk of their use.
Following the bombings, the Manhattan Project continued to oversee Operation Crossroads—a military-scientific experiment conducted at Bikini Atoll in 1946.
Sources differ regarding the end of the Manhattan Project. Some claim it ended with the atomic bombing of Hiroshima & Nagasaki, while other sources state the end of World War II.
The official end date recognised by US government bodies is August 25, 1947, when the project's management was transferred to the US Atomic Energy Commission (AEC) in 1946.
The AEC regulated nuclear energy and weapons development while also promoting peaceful applications of atomic energy.
In 1974, the AEC disbanded, with its functions divided between the Nuclear Regulatory Commission and the Department of Energy.
