by Paul Ham
If his recruiters meant to fan his ego, they misunderstood the burly engineer. To a man of Groves’ self-worth and overweening ego, personal success was a given. “If I can’t do the job, no one man can,” he later confided in his memoirs.16 Yet despite this confidence in himself, Groves had hesitated before accepting the job, wanting assurances that the bomb could be built. At the time, the budget was a mere $85 million (it would balloon to more than $US2 billion – or about US$26 billion in 2014 figures); the science seemed vague and unformed; and his then rank of colonel did not exert the necessary authority. He need not have worried: The army met his needs immediately. He was promoted on the spot to brigadier general, and granted his other key demands – top-level security clearance, a virtually unlimited budget and total operational control. Groves accepted the job in August 1942.
One of his first priorities was to corner the supply of fissile material. Within his first year in the position, Groves sent this message to senior officials:
On May 11, 1943, the MED entered into a fixed-fee ($1.00) cost contract with Union Mines Dev Corp to determine the world resources of uranium and, to the extent possible, bring such resources under the control of the US Government.17
Groves thus commandeered the world’s available supplies of yellowcake.
The general’s secret empire grew rapidly between 1942 and 1944, to embrace city offices, university laboratories and secret factories on remote prairies, from Oklahoma to Manhattan. Weekly, Groves’ private train shot through the dark fields of the Midwest towards another trembling recipient of his wrath. His baleful stare and snap decisions left a trail of anxiety. His memos were brief and abrupt, regardless of the seniority of the recipient. He had no time for small talk or pleasantries. He never shouted or swore. He led by quiet intimidation; those who angered him received “the silent treatment.”18 He closed meetings when he decided they were finished, even meetings with superiors. At his first meeting with President Roosevelt, he impertinently announced that he had to leave early.
The Scientists
The rest of the committeemen who entered Oppenheimer’s office that day were chiefly civilian scientists, with the exceptions of Colonel Lyle Seeman, Groves’ liaison officer at Los Alamos; Dr. Joyce C. Stearns, a scientist representing the US Army Air Forces; and Major Jack Derry, who wrote the summary notes of each meeting.
To call the scientists “experts” would be grossly to underplay their reputations in their chosen fields. Consider a sample:
Charles Lauritsen was a Danish émigré who had pioneered the development of radiation therapy for cancer patients in the 1930s. In the 1940s he worked on rocket systems and was closely involved in the creation of “pumpkins,” the mock-atomic bombs that the 509th Composite Group would use for target practice in Wendover Field, Utah.
David Dennison was a molecular scientist who had studied under Niels Bohr and who, before the war, had solved critical problems in physics that led to the creation of the first molecular microwave spectrograph. During the war Dennison specialized in the development of the VT (“variable time”) proximity fuse, a critical discovery that enabled the detonation of an explosive device at a predetermined distance from its target.
The physicist William Penney led the small British team at Los Alamos, which included the spy Klaus Fuchs (who would pass on atomic secrets to the Soviet Union).19 Penney was already regarded as one of the finest British mathematical physicists of the 20th century. He excelled in the mathematics of wave dynamics, chiefly in shock and gravitational waves. His special contributions to the atomic project were to model and predict the physical damage likely to be generated by the blast wave, and to calculate the height at which the bomb should be detonated to maximize its destructive power.
John von Neumann had already earned so many accolades that even his Los Alamos colleagues stood in awe of the great Hungarian-American mathematician. Prior to the war he had formulated a series of mathematical theorems (chiefly game and set theory), and published his masterpiece (one of his several), Mathematical Formulation of Quantum Mechanics. Von Neumann was intimately involved in the development of the atomic bomb, chiefly in mathematically modeling the explosion, assessing the likely death rate and solving the problem of how to detonate “Fat Man” – the weapon that would be tested in the New Mexico deserts in July and subsequently dropped on Nagasaki – by compressing its plutonium core. After the war, von Neumann became a founding father of the computer and, with Dr. Edward Teller, one of the leading scientific exponents of the hydrogen bomb.
The Target Committee Meets
The May 10 meeting was the Target Committee’s second. (There had been an agenda-setting discussion on April 27.) It was two days after Germany had surrendered. That did not mean, however, that Japanese cities automatically replaced German ones as targets for an atomic bomb. Japan had been the designated target for almost two years, since Churchill and Roosevelt signed the secret Hyde Park Agreement on September 18, 1944. It was Churchill who had named the target, noting that when the bomb was finally available, “it might perhaps, after mature consideration, be used against the Japanese.”20 Only Churchill and Roosevelt knew of this agreement; war secretary Henry Stimson and General George Marshall were not apprised of it until after the war. Yet the idea that Japan would be the target was uppermost in Groves’ and other senior officials’ minds towards the end of 1944, when the success of D-day and the Russian advance spelled Germany’s inevitable defeat.
For this reason, the committeemen were not expected to debate questions of “why” or “who” – those had been answered. Japan was the target. They were expected to draw up a list of the Japanese cities that best matched Groves’ criteria, and to decide how and when the chosen city or cities should be attacked. The critical questions related to the size and shape of the city, to what extent it had been preserved from conventional air raids (or firebombs), and whether it had any military installations. There were also technical details to be considered, such as the height of detonation and the risk of radiation to the delivery crews, but the key question was this: Which city would most effectively demonstrate the destructive power of an atomic bomb and shock Japan into submission?
Groves had been ruminating on the question since late 1944. At the April 27 meeting he had drawn up a short list. Major cities Tokyo and Yokohama were considered along with Yawata, in Fukuoka, Kyushu, but they were thought unsuitable – Tokyo was described as “all bombed and burned out” and “practically rubble, with only the palace grounds still standing.”21 Other cities seemed more promising. Hiroshima was “the largest untouched target,” having remained off the list of cities open to conventional attack drawn up by US Air Force General Curtis LeMay, who directed the strategic air raids over Japan. It also had special significance as the “jumping-off point” for many regiments leaving for the Pacific War, and earlier wars against China and Russia. “It should be given consideration,” the meeting concluded. The ancient Japanese capital Kyoto was also on the list. Groves regarded it as eminently suitable to show off the power of an atomic bomb: It was in pristine condition and heavily populated.
In sum, the committee agreed, the ideal target city for an atomic bomb should:
• possess sentimental value to the Japanese so its destruction would “adversely affect” the will of the people to continue the war
• have some military significance – munitions factories, troop concentrations, etc.
• be mostly intact, to demonstrate the awesome destructive power of an atomic bomb
• be big enough for a weapon of the atomic bomb’s magnitude.22
Hiroshima and Kyoto met these specifications; however, the final decision would await the May 10 meeting.
***
And so, with Groves’ express wishes uppermost in mind, the May 10 committee meeting began. Oppenheimer ran through the agenda:
A. Height of Detonation
B. Report on Weather and Operations
C. Gadget Jettisoning
and Landing
D. Status of Targets
E. Psychological Factors in Target Selection
F. Use Against Military Objectives
G. Radiological Effects
H. Coordinated Air Operations
I. Rehearsals
J. Operating Requirements for Safety of Airplanes
K. Coordination with 21st Program.23
Whether or to what extent the targeted cities had military installations was not discussed at this point, according to the minutes.24
Dr. Stearns named the targets on an updated short list in order of preference: Kyoto, Hiroshima and Yokohama, plus two new cities, Kokura, on the island of Kyushu, and Niigata, the capital city of Niigata Prefecture, on the north-west coast of Honshu.
The target list was always being reshuffled or amended, according to new priorities. Nagasaki had not yet made the cut. These five cities were all “large urban areas of more than three miles in diameter”; “capable of being effectively damaged by the blast”; and “likely to be unattacked by next August.”25 Of these, Kyoto and Hiroshima were classified as “AA” targets, because they best matched Groves’ criteria put forward prior to the meeting.
Kyoto, a large industrial city with a population of one million, met most of the committee’s criteria. Thousands of Japanese workers and hundreds of businesses had moved there to escape destruction elsewhere. Furthermore, Kyoto was a cultural and intellectual center, meaning the residents were “more likely to appreciate the significance of such a weapon as the gadget.” Groves ranked Kyoto his preferred no. 1 target, and von Neumann backed the choice of Kyoto as the target for the first atomic bomb.
Hiroshima, a city of 318,000, held similar appeal. It was “an important army depot and port of embarkation,” the meeting heard, situated in the middle of an urban area “of such a size that a large part of the city could be extensively damaged.” The hills that surrounded the city were “likely to produce a focusing effect which would considerably increase the blast damage.” On top of this, Hiroshima’s location within the Ota River delta meant that it was not a good target for firebombs, and would likely remain intact until the atomic bomb was ready.
The committeemen then heard the case for the remaining targets.
Yokohama was classified as an “A” target. It was an important urban industrial area and had so far been untouched. Industrial activities there included aircraft manufacture, machine tools, docks, electrical equipment and oil refineries. The committee was informed that:
As the damage to Tokyo has increased, additional industries have moved to Yokohama. It has the disadvantage of the most important target areas being separated by a large body of water and of being in the heaviest anti-aircraft concentration in Japan. For us it has the advantage as an [alternative] target for use in case of bad weather [and] of being rather far removed from the other targets considered.
Kokura was an ancient castle town that guarded the Straits of Shimonoseki. It hosted one of Japan’s biggest arsenals, surrounded by urban industrial structures, including coal and ore docks, steelworks, extensive railway yards and an electric power plant. Replete with military vehicles, ordnance, heavy naval guns and, reportedly, poison gas, this arsenal made Kokura the most obvious military target. Its dimensions were such that if a bomb were properly placed, “full advantage could be taken of the higher pressures immediately underneath the bomb for destroying the more solid structures,” while at the same time “considerable blast damage could be done to more feeble structures further away.” Like Yokohama, Kokura was classified as an A target.
Niigata was a port of embarkation on the north-west coast of Honshu. The committee members were told that:
[The city’s] importance is increasing as other ports are damaged. Machine tool industries are located there and it is a potential center for industrial dispersion. It has oil refineries and storage.
Niigata was classified as a “B” target. Its industrial plants were built of fire-resistant materials, and its houses constructed from heavy plaster, to protect against harsh winters. Hence, it was less combustible.
The possibility of bombing the Japanese emperor’s palace was also raised – a spectacular idea, they concurred, but militarily impractical. “It was agreed that we should not recommend it . . . [but] should obtain information [that might] determine the effectiveness of our weapon against this target,” the meeting decided. In any case, Tokyo, already firebombed several times, had been struck from an earlier list because an atomic bomb would merely “make the rubble dance,” to paraphrase Churchill.
The meeting barely touched upon whether the cities – with the exception of Kokura – had any appeal as military targets, or what their military functions were. There wasn’t much to discuss: Hiroshima’s port and its main industrial and military districts were located outside the urban regions, to the south-east of the city – well away from the target zone of the city center. A few thousand conscripts unfit for battle were garrisoned in the military barracks in the center of town, but it was otherwise populated by civilians.26 Japan’s ancient capital of Kyoto had no significant military installations either. However, its beautiful wooden shrines and temples recommended it, as Groves had said earlier, as both a “sentimental” and highly combustible target.
The committee moved on to the risks. Oppenheimer briefly assessed the radiation risk: US aircraft should not fly within two and a half miles of the detonation point, he advised, to “avoid the cloud of radioactive materials.” The risks would be discussed in greater detail at the next meeting, on the following day. The radiation risk to Japanese civilians was not discussed at any of the meetings of the Target Committee.
The committeemen next raised the question of whether incendiary bombers should attack the city after the nuclear strike. “This has the great advantage,” said one committee member, “that the enemies’ fire-fighting ability will probably be paralyzed by the gadget so that a very serious conflagration [will start].” The ensuing firestorm, however, might confuse photo-reconnaissance of the atomic damage and subject aircrews to radioactive contamination. For this reason, they rejected the proposal that firebombing raids should follow the atomic bomb.
Summing up, the committeemen unanimously agreed that the bomb should be dropped, without warning, on a large city center, the psychological impact of which should be so spectacular as to ensure “international recognition” of the new weapon. Groves received a full report of the proceedings on May 12.27
***
The Target Committee met the next day, May 11, to discuss the technical aspects of the mission. Before the meeting, Oppenheimer sent Farrell a longer description of the likely effects of radiation. The uranium bomb, he warned, as distinct from the plutonium bomb, being concurrently developed, would release toxic material equivalent to a billion single lethal doses; and radiation emissions would be lethal within a 1-mile radius.
Within a second of the blast, gamma radiation capable of penetrating concrete and packed soil equivalent to about 1012 curies would coat a large section of the targeted city, falling, within a day, to “about 10 million curies.” (One curie is the level of radiation emitted by a single gram of radium.) “If the bomb is delivered during rain,” Oppenheimer added, “most of the active material will be brought down . . . in the vicinity of the target area.” Otherwise, the radioactive material would spread over a wide area – unless the targeted city was surrounded by hills, like Hiroshima, which would contain the spread of the radioactive material, maximizing the damage and casualty rate.
Exposure to gamma rays causes diffuse damage throughout the human body, including radiation sickness, cell death due to damaged DNA, and increased incidence of cancer. The full effects were not fully understood at the time, but the scientists certainly knew the lethal properties of radiation, for which there was ample evidence (including the “Radium Girls,” young workers in a watch factory in New Jersey who, in 1917, had ingested lethal amounts of radium from fluorescent paint, by licking
their brushes to give them a fine point; dead fish in the rivers near Manhattan Project sites; and the Curies’ findings, to name a few).
Oppenheimer therefore warned that the delivery aircraft and follow-up planes should maintain a minimum distance of 2.5 miles from the detonation point to avoid radioactive contamination. Monitoring of ground radiation in the vicinity would be necessary for some weeks, he said, after which the area should be “quite safe to enter.”28
***
The Target Committee regrouped at the Pentagon on May 28 (Oppenheimer sent a representative). Two individuals critical to the success of the atomic mission addressed the committee. They were a pilot, Colonel Paul Tibbets, and a flight commander, Frederick Lincoln Ashworth. Both had had a long involvement in the nuclear mission and were fully apprised of every secret associated with the Manhattan Project. And both were, crucially, extremely good at their jobs.
Tibbets
Tibbets had been selected to fly the plane that would deliver the first atomic bomb. The youngest man in the room, Tibbets carried himself with a maturity beyond his 30 years. He seemed unperturbed at being among the very few who knew the true purpose of the mission – or perhaps he simply did not feel as other men do? No plane had dropped an atomic bomb; none had flown out of a radioactive cloud. Yet he was calm and cool, as if this were an everyday task he had been given to do.
Tibbets’ technical skill and proven courage had drawn the attention of the top brass at the US Army’s Strategic Air Service. A veteran of dozens of combat missions over Europe and North Africa, he was among the most experienced B-29 test pilots and one of the finest bomber pilots in the US Air Force. He was exceptionally brave, too: Tibbets had flown the lead plane in the Americans’ first daylight heavy bomber mission over occupied Europe on August 17, 1942, and again in the first American raid of more than 100 bombers on October 9 that year.
