From Fission to the Einstein Letter: How the Atomic Bomb Began, 1938–1942

In the week before Christmas 1938, in a laboratory of the Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem, the chemist Otto Hahn and his assistant Fritz Strassmann kept finding barium where barium had no business to be. They had bombarded uranium, the heaviest element then known, with slow neutrons, expecting to make elements close to it in weight. Their chemistry said they had made something barely half as heavy. On 19 December Hahn wrote about the puzzle to his longtime partner Lise Meitner, a physicist who had fled Nazi Germany five months earlier and was spending a lonely first winter in Stockholm. Over the next three and a half years that result travelled from Berlin to Sweden, Copenhagen, New York, a summer cottage on Long Island, the White House and a British committee room, and ended in a U.S. Army engineer district with an office on lower Broadway.

Why it mattered

Every later chapter of this collection, from the graphite pile under a Chicago football stand to the bombs over Hiroshima and Nagasaki, depends on decisions taken in the three and a half years between the discovery of fission and the creation of the Manhattan Engineer District. In that time a laboratory curiosity became a recognized military possibility, and the United States moved from a committee with $6,000 to spend to a program measured in tens of millions of dollars with the President’s personal backing.

The story is often told as if a single letter from Albert Einstein set it all in motion. The record is more complicated and more interesting. The letter mattered: it put the question on Roosevelt’s desk in October 1939. But for nearly two years afterward the American effort was small, cautious and slow. What turned it into a crash program was a combination of things: British calculations, set down in the MAUD Committee’s reports of July 1941, showing that a bomb needed kilograms rather than tons of uranium-235; the persistence of a handful of scientists, many of them refugees from Hitler’s Europe, who feared that Germany would get there first; the discovery of plutonium at Berkeley; and the reorganization of American science for war under Vannevar Bush. Pearl Harbor, on 7 December 1941, came one day after Bush launched the accelerated program, and the war removed the last doubts about money.

It also mattered how the project was organized. When the Army Corps of Engineers took over construction in the summer of 1942, the bomb effort acquired the shape it kept for the rest of the war: civilian scientists at university laboratories, industrial contractors building and running enormous plants, and a military district, named after the borough where its first office stood, holding the money, the land, the priorities and the secrets.

Barium in Berlin

The experiments that led to fission began in Rome. In 1934 Enrico Fermi’s group bombarded element after element with neutrons, the uncharged particles discovered by James Chadwick two years earlier, and reported that uranium produced new radioactive substances which they took to be elements heavier than uranium. Fermi received the Nobel Prize in Physics in 1938 partly for this work. In hindsight, his group had split uranium atoms without recognizing it; the U.S. Department of Energy’s history of the project notes plainly that Fermi produced fission in 1934 without realizing what he had done.

In Berlin the radiochemist Otto Hahn and the physicist Lise Meitner, who had worked together since 1907, took up the problem with Fritz Strassmann, a younger chemist. Meitner was an Austrian of Jewish descent. Austria’s annexation in March 1938 made her a German subject and stripped away the protection her Austrian citizenship had given her; in July 1938, with help from Dutch colleagues and from Hahn, she slipped across the Dutch border and went on to Stockholm, where she took a place at Manne Siegbahn’s institute. Hahn and Strassmann carried on in Berlin and kept writing to her.

In December 1938 Hahn and Strassmann identified one of the products of neutron bombardment of uranium as barium, element 56, not radium, element 88, as they had expected. Hahn described the result to Meitner in a letter of 19 December, asking whether she could find any physical explanation for it. Their paper reporting the chemistry was published in Die Naturwissenschaften on 6 January 1939. It was careful to the point of reluctance: as chemists they had to say barium; as nuclear chemists they hesitated to draw a conclusion that ran against all experience in physics.

“Fission”: Meitner and Frisch

Meitner received Hahn’s letter as she was leaving Stockholm to spend Christmas with friends at Kungälv, near Gothenburg. Her nephew Otto Robert Frisch, a physicist working at Niels Bohr’s institute in Copenhagen, joined her there. Walking in the snow, the two of them worked out an explanation using Bohr’s model of the nucleus as a liquid drop. A uranium nucleus, large and only loosely held together, could be set wobbling by the capture of a neutron, stretch, and split into two smaller nuclei of roughly equal size, which would fly apart with great energy. Their estimate of that energy, about 200 million electron volts for each split, matched the mass that disappeared in the process, by Einstein’s relation between mass and energy.

Back in Copenhagen, Frisch confirmed the large bursts of energy experimentally on 13 January 1939. He borrowed a name for the process from biology, after asking the American biologist William A. Arnold, then working in Copenhagen, what the division of a living cell was called: “fission.” Meitner and Frisch’s explanation appeared in Nature on 11 February 1939, and Frisch’s experimental note a week later. Hahn received the 1944 Nobel Prize in Chemistry, alone, for the discovery; Meitner did not share it, a decision now widely regarded as an injustice.

Bohr carries the news to America

Frisch told Bohr of the explanation just before Bohr sailed for the United States in January 1939. Bohr landed in New York on 16 January with his collaborator Léon Rosenfeld, who mentioned the news at a Princeton physics meeting. On 26 January Bohr announced it publicly at the fifth Washington Conference on Theoretical Physics, held at George Washington University. Within days physicists at the Carnegie Institution’s Department of Terrestrial Magnetism, at Columbia, at Johns Hopkins and at Berkeley had reproduced the effect; Merle Tuve’s group at the Carnegie Institution showed the fission pulses to conference participants on their instruments. A bronze plaque in George Washington University’s Corcoran Hall marks the room.

Two further questions decided whether fission was a curiosity or a danger. The first was whether each fission released spare neutrons that could split further nuclei, making a chain reaction possible. In early March 1939 two groups at Columbia, Leo Szilard with Walter Zinn, and Fermi with Herbert Anderson, found that it did; Frédéric Joliot-Curie’s group in Paris reported the same thing in Nature in April. The second was which uranium was fissioning. Natural uranium is more than 99 percent uranium-238, with about 0.7 percent of the lighter isotope uranium-235. Bohr, working with John Wheeler at Princeton, argued in early 1939 that slow neutrons split only the rare uranium-235. In March 1940 John Dunning’s group at Columbia confirmed it with a tiny sample separated by Alfred Nier at the University of Minnesota. That result was the root of the industrial problem that dominates the following chapters: to make a uranium bomb, uranium-235 would have to be separated from uranium-238, two forms of the same element that chemistry cannot tell apart.

Szilard’s fear: Germany and the uranium

Leo Szilard, a Hungarian-born physicist who had left Germany in 1933, had been thinking about chain reactions for longer than anyone. In September 1933 in London, provoked by a newspaper report of Ernest Rutherford’s dismissal of atomic energy as impractical, he conceived the idea of a nuclear chain reaction sustained by neutrons, and in 1934 he filed a British patent on it, which he later assigned to the British Admiralty to keep it secret. He had not known which element would work. Fission answered the question, and by early 1939 Szilard, now at Columbia, was trying to persuade colleagues in America and Europe to stop publishing on neutron multiplication. Fermi was skeptical, Joliot refused, and the voluntary secrecy that physicists adopted in 1940 came too late to keep the basic facts from anyone.

The fear driving Szilard and his fellow Hungarian refugees, Eugene Wigner and Edward Teller, was specific. Fission had been discovered in Berlin. Germany had first-rate physicists, among them Werner Heisenberg, and in 1939 it controlled the uranium mines of Joachimsthal in occupied Czechoslovakia. German research did begin that year: a meeting at the Reich Ministry of Education in April 1939, and from September an army ordnance program, the so-called Uranverein (“uranium club”). Nobody outside Germany could know how far it would get. The answer, learned by the Alsos mission only in 1944 and 1945, was not very far: German scientists never achieved a self-sustaining chain reaction and never approached a bomb. In 1939, however, the refugees thought the worst was the prudent assumption, and they believed that the best supply of high-grade uranium outside Europe, in the Belgian Congo, must be kept out of German hands.

The letter from Peconic

Szilard’s first idea was to warn the Belgian government through Einstein, who knew the Queen Mother, Elisabeth. On 12 July 1939 Szilard and Wigner drove out to the North Fork of Long Island, where Einstein was spending the summer in a rented cottage at Nassau Point, Peconic, near Cutchogue. Einstein had not considered the possibility of a chain reaction, but grasped it at once and agreed to help. Through the economist Alexander Sachs, a Lehman Corporation adviser with access to President Roosevelt, the plan changed: the letter would go to the President. Szilard returned to Peconic with Teller driving, Einstein dictated a draft in German, and Szilard prepared a long and a short English version. The longer one, signed by Einstein, is dated 2 August 1939 and was sent with an explanatory memorandum by Szilard. Szilard handed the signed letter to Sachs in mid-August (Lanouette).

The letter is short, two typed pages. It tells Roosevelt that, on the basis of recent work by Fermi and Szilard and of Joliot’s work in France, a chain reaction in a large mass of uranium had become possible and might lead to bombs of a new type, one of which, carried by boat and exploded in a port, might destroy the port and some of the surrounding area. It judged such bombs probably too heavy to carry by air. It pointed out that the United States had only poor uranium ores, that Canada and Czechoslovakia had some, and that the most important source was the Belgian Congo. It recommended that the administration keep in touch with the physicists working on chain reactions and that it speed the experimental work, then limited by university budgets. And it ended with the detail Szilard most wanted the President to notice: that Germany had stopped the sale of uranium from the Czechoslovak mines it had seized, and that the son of the German Under Secretary of State, Carl Friedrich von Weizsäcker, worked at the Kaiser Wilhelm Institute in Berlin, where American uranium work was being repeated.

Sachs did not see Roosevelt until 11 October 1939. Germany had invaded Poland on 1 September, and the President’s attention was on neutrality legislation and the war in Europe. When the meeting came, in the presence of Roosevelt’s secretary and military aide, Brig. Gen. Edwin “Pa” Watson, of Lt. Col. Keith Adamson of Army Ordnance and of Cmdr. Gilbert Hoover of the Navy, Sachs read his own summary rather than the letter. By Sachs’s later account, he returned the next morning, told the President a story about Napoleon rejecting Robert Fulton’s steamship, and Roosevelt turned to Watson and said that this required action. That account is recollection, given years afterward, and its details cannot be checked against a contemporary record; what is documented is the result. Roosevelt wrote to Einstein on 19 October 1939 that he had set up a board to study the matter, and the board met for the first time on 21 October.

$6,000 and two slow years

The Advisory Committee on Uranium was chaired by Lyman J. Briggs, a soil physicist and the director of the National Bureau of Standards, with Adamson and Hoover as its service members. At its first meeting, at the Bureau of Standards on 21 October 1939, Szilard, Wigner and Teller described the chain-reaction work. Adamson was openly skeptical of new weapons; Teller asked for money to buy graphite for a Fermi–Szilard experiment. The committee recommended support, and Adamson authorized $6,000 for uranium and graphite, money that did not reach Columbia until early 1940 (Hewlett and Anderson). The committee’s report of 1 November 1939 treated a bomb as a possibility, not a likelihood, and its main interest was in a chain reaction as a source of power, perhaps for submarines.

Einstein, prodded by Szilard and Sachs, wrote again on 7 March and 25 April 1940 urging faster action. In June 1940, as France fell, Vannevar Bush, president of the Carnegie Institution of Washington and former dean of engineering at the Massachusetts Institute of Technology, persuaded Roosevelt to create the National Defense Research Committee (NDRC) to mobilize civilian science for the military. The Uranium Committee became a subcommittee of the NDRC, and in September 1940 Bush told Briggs it would have $40,000 for the work. On 28 June 1941, by Executive Order 8807, Roosevelt created the Office of Scientific Research and Development (OSRD) with Bush as director, giving it authority to fund development as well as research; James B. Conant, the president of Harvard, took over the NDRC under it, and the uranium work became the OSRD’s Section on Uranium, later called S-1.

The science moved faster than the administration. At Berkeley in 1940 Edwin McMillan and Philip Abelson identified element 93, neptunium, produced when uranium-238 captures a neutron. In February 1941 Glenn Seaborg, Arthur Wahl and Joseph Kennedy, working with McMillan’s method, chemically identified element 94, later named plutonium, in a sample made in Lawrence’s 60-inch cyclotron, and in March 1941 Seaborg, Kennedy and Emilio Segrè showed that its isotope plutonium-239 split with slow neutrons as readily as uranium-235. That opened a second road to a bomb. Plutonium could be made from the abundant uranium-238 in a chain-reacting pile and then separated by chemistry, which, unlike the separation of uranium isotopes, was a familiar industrial art.

The British push: Frisch, Peierls and MAUD

The decisive calculation was made in England. In March 1940 Otto Frisch, now at the University of Birmingham, and Rudolf Peierls, a German-born theoretical physicist there, wrote a short memorandum arguing that a bomb did not need the tons of uranium that most physicists had assumed. Using nearly pure uranium-235 and fast neutrons, they estimated, a modest quantity would explode with the force of thousands of tons of TNT, and the radiation it released would make the area around it dangerous. They also warned that such a weapon could hardly be used without killing large numbers of civilians. Mark Oliphant, their department head, sent the memorandum to Sir Henry Tizard, who chaired the British government’s scientific committee on air warfare.

The result was a committee under the physicist George Paget Thomson, which met first at the Royal Society on 10 April 1940. Its odd name came from a telegram Bohr had sent from occupied Denmark that ended with a message to “Maud Ray Kent,” which the British read as a code; Maud Ray was in fact a former governess of the Bohr children who lived in Kent. The MAUD Committee’s two reports, approved in July 1941, concluded that a uranium bomb was practicable and could be decisive in the war; estimated that one using about 25 pounds of uranium-235 would equal about 1,800 tons of TNT; and recommended that the work be given the highest priority. A separate report judged that atomic power was promising but could wait until after the war (Gowing, 1964). Britain began its own program, under the cover name Tube Alloys, after Churchill approved it at the end of August 1941.

Briggs had received the MAUD drafts and kept them in his safe. In late August 1941 Oliphant flew to the United States, ostensibly on radar business, and found that the people who mattered had not read them. He went to see Briggs and the Uranium Committee, then Lawrence at Berkeley, then Conant and Bush, pressing the argument that a bomb could be made in time to affect the war. Lawrence took the case to Arthur Compton and Conant. On 3 October 1941 Conant received the final MAUD report from Thomson, and Bush had the official text in hand when he went to the White House six days later.

9 October 1941: Roosevelt decides

On 9 October 1941 Bush met Roosevelt and Vice President Henry A. Wallace at the White House and summarized the British conclusions, the likely cost and the time needed. The President authorized him to find out, with the Army, what construction would be required, but limited the work for the moment to research and development; he wanted to decide himself on any move to production. He asked Bush to draft a letter so that he could take up the matter with Churchill directly, and he created a small group to decide policy: himself, Wallace, Secretary of War Henry L. Stimson, Army Chief of Staff Gen. George C. Marshall, Bush and Conant, later known as the Top Policy Group (DOE OSTI history; Hewlett and Anderson). Roosevelt never attended its meetings, but from that day the bomb was his project.

An American review followed. A committee of the National Academy of Sciences under Arthur Compton reported on 6 November 1941 that a fission bomb was possible, gave a broad estimate of the uranium-235 it would need, and put the cost of isotope separation plants at $50 million to $100 million; Bush sent its findings to the President on 27 November. On Saturday, 6 December 1941, Bush and Conant met the program chiefs and launched an accelerated effort: Harold Urey of Columbia on gaseous diffusion, the centrifuge and heavy water; Lawrence on electromagnetic separation; Compton on the chain reaction and the theory of the weapon; and Eger Murphree of Standard Oil Development Company in charge of engineering and pilot plants. The next morning the Japanese attacked Pearl Harbor. The S-1 Section met on 18 December in what the official historians call an atmosphere of enthusiasm and urgency.

Roosevelt answered Bush’s report with a handwritten note of 19 January 1942: “V.B. OK — returned — I think you had best keep this in your own safe FDR.” On 9 March Bush reported that a bomb might be ready in 1944 and recommended that the Army take over construction once the pilot work was done. The President’s reply of 11 March is the clearest statement of his wishes in the record.

In their words

I think the whole thing should be pushed not only in regard to development, but also with due regard to time. This is very much of the essence.

Spring 1942: four roads to a bomb

No one in early 1942 could say which method of making bomb material would work, and the program’s leaders decided to pursue several at once rather than gamble on one. For uranium-235 there were three serious candidates. Gaseous diffusion, championed by Urey and John Dunning at Columbia, would pump a uranium gas through porous barriers thousands of times, exploiting the slightly faster passage of the lighter molecules. The centrifuge, worked on by Jesse Beams at the University of Virginia, would spin the gas so that the heavier isotope moved outward. Electromagnetic separation, Lawrence’s method, would ionize uranium, accelerate it and bend the ions in a magnetic field so that the lighter ones followed a slightly tighter curve. Thermal diffusion, developed by Philip Abelson for the Navy, was not yet part of the Army’s plan. The fourth road was plutonium, which required first building a chain-reacting pile.

Compton gathered the pile work, until then split between Columbia, Princeton and Chicago, at the University of Chicago, announcing the decision on 24 January 1942. The new Metallurgical Laboratory, a cover name, brought Fermi and his group from New York in the spring. In May 1942 the S-1 leaders agreed to push all four methods through the pilot-plant stage; the centrifuge was dropped at the end of the year. On 17 June 1942 Bush sent Roosevelt a plan for the next fiscal year that the President approved: $54 million for construction by the Army Corps of Engineers, $31 million for OSRD research and development and $5 million in reserve (Hewlett and Anderson; Jones). In the same month the S-1 Executive Committee, with Bush’s deputy Conant in the chair and Briggs, Compton, Lawrence, Urey and Murphree as members, replaced the old section, and on 25 June it picked Stone & Webster of Boston as the main engineering contractor for the plants in Tennessee.

The Army takes over: the Manhattan Engineer District

The Army’s part began quietly. In June 1942 the Chief of Engineers, Maj. Gen. Eugene Reybold, chose Col. James C. Marshall, a West Pointer then serving as district engineer at Syracuse, New York, to direct the construction work. Brig. Gen. Wilhelm D. Styer, chief of staff of the Army’s Services of Supply under Lt. Gen. Brehon B. Somervell, oversaw it in Washington. The work was first given the cover name “Laboratory for the Development of Substitute Materials,” or DSM. Marshall set up his office in New York, where the Corps of Engineers’ North Atlantic Division had its headquarters on the 18th floor of 270 Broadway and where Stone & Webster also had offices, and close to Columbia, the main university contractor.

Corps of Engineers districts took their names from the city where their headquarters stood, and an unremarkable district name was better cover than DSM. Marshall and Col. Leslie R. Groves, then deputy chief of Army construction, agreed on “Manhattan,” and on 13 August 1942 Reybold issued the order creating the Manhattan Engineer District, effective 16 August (Jones; AHF). Within weeks “the Manhattan Project” was the common name for the whole enterprise. The district headquarters moved to Oak Ridge, Tennessee, in August 1943.

Marshall’s summer was spent on the problems that would define the next three years: finding land in Tennessee for the uranium plants, getting materials under a priority system in which the project ranked well below ships and aircraft, and deciding how far the Army should trust the scientists’ estimates. In September 1942 Edgar Sengier, the head of the Belgian mining company Union Minière du Haut Katanga, who in 1940 had shipped more than 1,000 tons of high-grade Congo uranium ore to a warehouse on Staten Island as a precaution, sold it to the Army; Marshall’s deputy, Lt. Col. Kenneth D. Nichols, closed the deal. Bush and the War Department’s leaders, however, were dissatisfied with the pace. On 17 September 1942 Somervell and Styer told Groves that he was to take charge of the whole project, with promotion to brigadier general. His first weeks in command are the subject of Chapter 2.

Timeline

From fission to the Manhattan District, 1933–1942

1. Sep 1933In London, Leo Szilard conceives a nuclear chain reaction sustained by neutrons; he files a patent in 1934.
2. 1934Fermi’s group in Rome bombards uranium with neutrons, producing fission without recognizing it.
3. Jul 1938Lise Meitner escapes from Germany through the Netherlands and settles in Stockholm.
4. Dec 1938Hahn and Strassmann find barium among the products of neutron-bombarded uranium; Hahn writes to Meitner on 19 December.
5. Late Dec 1938At Kungälv, Meitner and Frisch explain the result as the splitting of the nucleus.
6. 6 Jan 1939Hahn and Strassmann’s paper is published in Die Naturwissenschaften.
7. 13 Jan 1939Frisch confirms the energetic fragments experimentally in Copenhagen.
8. 16 Jan 1939Niels Bohr arrives in New York with the news.
9. 26 Jan 1939Bohr announces fission at the Washington Conference on Theoretical Physics; laboratories confirm it within days.
10. 11 Feb 1939Meitner and Frisch’s explanation, naming “fission,” appears in Nature.
11. Mar 1939Szilard and Zinn, and Fermi and Anderson, at Columbia find that fission releases neutrons.
12. 12 Jul 1939Szilard and Wigner visit Einstein at Nassau Point, Peconic.
13. 2 Aug 1939Date of the letter Einstein signs for Roosevelt.
14. 1 Sep 1939Germany invades Poland.
15. 11 Oct 1939Alexander Sachs presents the letter and his own summary to Roosevelt.
16. 21 Oct 1939First meeting of the Advisory Committee on Uranium under Lyman Briggs; $6,000 authorized.
17. Mar 1940The Frisch–Peierls memorandum in Birmingham; Dunning’s Columbia group confirms that uranium-235 fissions with slow neutrons.
18. 10 Apr 1940First meeting of the British MAUD Committee.
19. Jun 1940The National Defense Research Committee is formed under Vannevar Bush and absorbs the Uranium Committee.
20. Feb–Mar 1941Plutonium is identified at Berkeley and shown to fission with slow neutrons.
21. 28 Jun 1941Executive Order 8807 creates the Office of Scientific Research and Development.
22. Jul 1941The MAUD Committee approves its reports: a uranium bomb is practicable.
23. Late Aug 1941Mark Oliphant visits the United States and presses for action.
24. 9 Oct 1941Bush briefs Roosevelt and Wallace; the President authorizes exploration of a bomb and forms the Top Policy Group.
25. 6 Dec 1941Bush and Conant launch the accelerated S-1 program.
26. 7 Dec 1941Japan attacks Pearl Harbor.
27. 19 Jan 1942Roosevelt approves Bush’s report: “keep this in your own safe.”
28. 24 Jan 1942Compton concentrates the pile work at Chicago in the Metallurgical Laboratory.
29. 11 Mar 1942Roosevelt tells Bush the work should be pushed “with due regard to time.”
30. 17 Jun 1942Bush’s plan for Army construction is approved by Roosevelt.
31. 13 Aug 1942The Manhattan Engineer District is established under Col. James C. Marshall.
32. 17 Sep 1942Col. Leslie R. Groves is ordered to take charge of the project.

Questions readers ask

Did Einstein write the letter to Roosevelt?

Einstein signed it and dictated a German draft of its content at Peconic, but Leo Szilard drafted the English text and supplied the technical substance, after discussions with Wigner and Teller. Einstein’s name was used because Roosevelt and the public knew it; Szilard was unknown outside physics.

Why is it called the Manhattan Project?

Because the Army Corps of Engineers named its districts after the city where the district office was, and the new district’s first office was in Manhattan, at 270 Broadway. The original cover name, “Development of Substitute Materials,” was thought too likely to attract curiosity. Almost none of the actual work was done in Manhattan, although Columbia University, the Kellex Corporation’s design offices and a warehouse of Congo uranium ore on Staten Island were in New York.

Was Germany really close to a bomb?

No. German scientists began work in 1939, but their program was small, divided among competing groups and short of material, and it never produced a self-sustaining chain reaction. That was not known in the United States until the Alsos mission captured German scientists and records in 1944 and 1945. In 1939–42, the fear of a German bomb was reasonable and was the main motive of the refugee physicists who pushed the American effort.

What was the MAUD Report, and why did it matter so much?

It was the British government committee’s conclusion, approved in July 1941, that a uranium bomb was practicable with a modest quantity of uranium-235 and could be ready within a few years. American scientists had been thinking in terms of tons of material and a long program focused on power. The British estimate, carried by Mark Oliphant and confirmed by Compton’s National Academy review, persuaded Bush and Conant that a bomb might be built in time to matter in the war.

Did the attack on Pearl Harbor start the Manhattan Project?

No. Roosevelt’s decision came on 9 October 1941, and Bush and Conant launched the accelerated program on 6 December, the day before the attack. Pearl Harbor removed any remaining doubts about money and urgency, and the project grew rapidly in 1942.

Why did Lise Meitner not share the Nobel Prize?

The Nobel Committee for Chemistry awarded the 1944 prize to Hahn alone, treating fission as a chemical discovery. Studies of the Nobel archives since they were opened, notably by Ruth Lewin Sime and Elisabeth Crawford, have concluded that the committee misjudged Meitner’s part, influenced by disciplinary bias, her exile and the difficulties of wartime communication.

How it connects

This chapter opens The Manhattan Project collection. Chapter 2 follows Leslie Groves into command in September 1942 and Fermi’s team to the first self-sustaining chain reaction under Stagg Field in Chicago on 2 December 1942; Chapter 3 goes to Tennessee, where the uranium methods chosen in 1942 became the plants of Oak Ridge. The war that framed these decisions is told elsewhere on the site: the German invasion that coincided with Sachs’s long wait for an appointment in the Invasion of Poland, the attack of 7 December 1941 in Pearl Harbor, and the struggle at sea that made a uranium shipment across the Atlantic in 1940 a risk in Battle of the Atlantic. The World War II hub lists all the collections.

Remembering it today

The apparatus of the fission discovery is displayed at the Deutsches Museum in Munich. A plaque in Corcoran Hall at George Washington University in Washington marks the room where Bohr announced fission on 26 January 1939, and Columbia University’s Pupin Hall, where the Columbia experiments were done, is a National Historic Landmark. The letter that Roosevelt received is held by the Franklin D. Roosevelt Presidential Library and Museum at Hyde Park, New York; Einstein’s summer cottage at Nassau Point is a private house. The building at 270 Broadway still stands at the corner of Chambers Street, unmarked.

The three main sites of the project, at Oak Ridge, Tennessee, Hanford, Washington, and Los Alamos, New Mexico, have been units of the Manhattan Project National Historical Park since 2015, managed by the National Park Service with the Department of Energy. The Atomic Heritage Foundation’s collection, now at the National Museum of Nuclear Science & History, includes the oral histories of Voices of the Manhattan Project, and the Department of Energy’s Manhattan Project: An Interactive History is a reliable free introduction.

Sources

• Hewlett, Richard G., and Oscar E. Anderson Jr. The New World, 1939–1946: A History of the United States Atomic Energy Commission, vol. 1. University Park: Pennsylvania State University Press, 1962. The official history; chapters 1–3 cover the period of this chapter.
• Jones, Vincent C. Manhattan: The Army and the Atomic Bomb. United States Army in World War II, Special Studies. Washington: U.S. Army Center of Military History, 1985. CMH Pub 11-10 (PDF).
• Gowing, Margaret. Britain and Atomic Energy, 1939–1945. London: Macmillan, 1964. The British official history, including the MAUD reports.
• Smyth, Henry DeWolf. Atomic Energy for Military Purposes. Princeton: Princeton University Press, 1945 (the “Smyth Report”).
• Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986.
• Lanouette, William, with Bela Silard. Genius in the Shadows: A Biography of Leo Szilard. New York: Charles Scribner’s Sons, 1992.
• Sime, Ruth Lewin. Lise Meitner: A Life in Physics. Berkeley: University of California Press, 1996.
• Groves, Leslie R. Now It Can Be Told: The Story of the Manhattan Project. New York: Harper & Row, 1962.
• Bird, Kai, and Martin J. Sherwin. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. New York: Alfred A. Knopf, 2005.
• U.S. Department of Energy, Office of History and Heritage Resources. The Manhattan Project: An Interactive History: “The Discovery of Fission” and “A Tentative Decision to Build the Bomb.”
• Atomic Heritage Foundation / National Museum of Nuclear Science & History. “The Manhattan Project Begins, 1942” and “Manhattan, NY.”
• Atomic Archive. Primary documents: Einstein’s letter, Roosevelt’s reply, the Frisch–Peierls memorandum, the MAUD Report, and Roosevelt’s memo to Bush of 11 March 1942.
• Library of Congress, In Custodia Legis. “Einstein’s Fateful Letter” (2020).
• Hahn, O., and F. Strassmann. “Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle.” Die Naturwissenschaften 27 (6 January 1939): 11–15. Meitner, L., and O. R. Frisch. “Disintegration of Uranium by Neutrons: A New Type of Nuclear Reaction.” Nature 143 (11 February 1939): 239–240.
• Wikipedia articles “Einstein–Szilard letter,” “MAUD Committee” and “Timeline of the Manhattan Project,” used as pointers to the sources above.

Photographs: U.S. government photographs from the Department of Energy and the Lawrence Berkeley Laboratory (Donald Cooksey), the National Institute of Standards and Technology, the Franklin D. Roosevelt Presidential Library and the Smithsonian Institution Archives, all public domain; Oren Jack Turner’s 1947 portrait of Einstein, public domain because its copyright was not renewed (Library of Congress); a 1913 photograph of Meitner and Hahn by an unknown photographer, public domain; and modern photographs of the Deutsches Museum display (J Brew, CC BY-SA 2.0) and of 270 Broadway (Americasroof, CC BY-SA 3.0); all via Wikimedia Commons. The insignia of the Manhattan Engineer District drawn for this collection is an illustration, not an official emblem.