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Part 2 The Atomic Bomb

1. Development of the Atomic Bomb
2. Target Selection and Orders for the Atomic Bombings
3.Tinian Island and the Special Atomic Bombing Unit
4. Nagasaki Bombing Records
5. The Aiming Point Specified in the Field Operation Order

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1. Development of the Atomic Bomb

In a statement released to the press on August 6, 1945, U.S. President Harry S. Truman announced the use of an atomic bomb on Hiroshima and outlined the process of development as follows:

Before 1939 it was the accepted belief of scientists that it was theoretically possible to release atomic energy. But no one knew any practical method of doing it. By 1942, however, we knew that the Germans were working feverishly to find a way to add atomic energy to the other engines of war with which they hoped to enslave the world. But they failed. We may be grateful to Providence that the Germans got the V-1’s (unmanned jet-powered bombs) and V-2’s (ballistic-missile rockets) late and in limited quantities and even more grateful that they did not get the atomic bomb at all.
　The battle of the laboratories held fateful risks for us as well as the battles of the air, land and sea, and we have now won the battle of the laboratories as we have won the other battles.
　Beginning in 1940, before Pearl Harbor, scientific knowledge useful in war was pooled between the United States and Great Britain, and many priceless helps to our victories have come from that arrangement. Under that general policy the research on the atomic bomb was begun. With American and British scientists working together we entered the race of discovery against the Germans. 80

To summarize, in August 1942, the United States Army Corps of Engineers launched a program to develop the atomic bomb with General Leslie R. Groves serving as executive officer. Called the “Manhattan Engineering District” at first, the program later came to be known as the “Manhattan Project.” In order to ensure that secrecy surrounded the development and manufacture of the atomic bomb, enormous factories were constructed at remote mountainous locations in a number of states, including the Los Alamos Laboratory, which later became the atomic bomb assembly plant under the direction of Dr. J. Robert Oppenheimer, and the facilities at Oak Ridge and Hanford.
　At these factories code-named “Manhattan Plants,” “the people employed during the peak construction period numbered as many as 125,000. Few know what they have been producing. They see great quantities of material going in and they see nothing coming out of these plants, for the physical size of the explosive charge is exceedingly small.” 81
　Like the name of the undertaking itself, every aspect of the Manhattan Project had a code name, a fact that reveals the top-secret nature of production and the strict level of confidentiality enforced. The original code name for the atomic bomb was “S-1.”
　These efforts succeeded in producing uranium and plutonium atomic bombs by 1945.
　The plutonium atomic bomb was developed after the uranium atomic bomb (the type used on Hiroshima) and utilized the radioactive chemical element plutonium first synthesized in 1940. The explosive power of the uranium bomb had already been calculated, making further experiments unnecessary. A test was needed, however, for the new plutonium bomb because a number of technical issues remained unresolved. Herbert Feis explains the reasons behind this decision, stating that there were two reasons for conducting the test, one being the complexity and delicacy of the implosion mechanism, and the other being the need to confirm the bomb’s explosive power in order to calculate the altitude at which it should be detonated over Japan to achieve optimal results. 82
　The test was performed in the middle of the New Mexico desert at dawn on July 16, 1945, during a heavy rainfall. The following are excerpts from the press release issued by the U.S. War Department on July 16, 1945:

Humankind’s successful transition to a new age, the Atomic Age, was ushered in on July 16, 1945 before the eyes of a tense group of renowned scientists and military men gathered in the desert lands of New Mexico to witness the first end results of their $2,000,000,000 effort. Here in a remote section of the Alamogordo Air Base 120 miles (192 km) southeast of Albuquerque the first man-made atomic explosion, the outstanding achievement of nuclear science, was achieved at 5:30 a.m. of that day. Darkening heavens, pouring forth rain and lightning immediately up to the zero hour, heightened the drama…
　Final assembly of the atomic bomb began on the night of July 12 in an old ranch house. As various component assemblies arrived from distant points, tension among the scientists rose to an increasing pitch…
　On Saturday, July 14, the unit, bound to determine the success or failure of the entire project, was elevated to the top of the steel tower [30 m in height]…
　The weather, unusual and upsetting, blocked out aerial observation of the test. It even held up the actual explosion scheduled at 4:00 a.m. for an hour and a half…
　General Groves rejoined Dr. Conant and Dr. Bush, and just before the test time they joined the many scientists gathered at the Base Camp [approximately 16 km south of the steel tower]. Here all present were ordered to lie on the ground, face downward, heads away from the blast direction…
　The time signals, ‘minus 20 minutes, minus 15 minutes,’ and on and on increased the tension to the breaking point as the group in the control room [9 km south of the steel tower] which included Dr. Oppenheimer and General Farrell held their breaths, all praying with the intensity of the moment which will live forever with each man who was there. At ‘minus 45 seconds,’ robot mechanism took over and from that point on the whole great complicated mass of intricate mechanism was in operation without human control…
　At the appointed time there was a blinding flash lighting up the whole area brighter than the brightest daylight. A mountain range three miles (4.8 km) from the observation point stood out in bold relief. Then came a tremendous sustained roar and a heavy pressure wave which knocked down two men outside the control center. Immediately thereafter, a huge multi-colored surging cloud boiled to an altitude of over 40,000 feet (12,000 m). Clouds in its path disappeared.
　The test was over, the project a success.
　The steel tower had been entirely vaporized. Where the tower had stood, there was a huge sloping crater [366 m in diameter]. Dazed but relieved at the success of their tests, the scientists promptly marshaled their forces to estimate the strength of America’s new weapon. To examine the nature of the crater, specially equipped tanks were wheeled into the area. 83

In his book Seven Hours to Zero, Joseph L. Marx provides the following anecdote:

Early on the morning of the test, Dr. Enrico Fermi, known to be one of the fastest persons in the world with an engineering slide rule, carefully dropped small pieces of paper at designated places on the ground at the test site. He said that he could estimate the explosive power of the bomb based on the speed at which the pieces flew away, even before the instruments had finished measuring the actual strength. At the time of the explosion, Fermi observed the movement of the pieces of paper. After measuring and calculating for a little while, he estimated that the explosion would be equivalent to a detonation of around 20,000 tons of TNT. A few days later, precise calculations and measurements were performed on the explosion, and it was revealed that his estimate was very close to the actual figure. 84

U.S. President Harry S. Truman, who was in the suburbs of Berlin to attend the Potsdam Conference, received word that the new bomb employing Plutonium-239 had been tested successfully in New Mexico. Coded in cryptic language, the report read, “Operated on this morning. Diagnosis not yet complete, but results seem satisfactory and already exceed expectations.”

　President Truman, Secretary of War Henry L. Stimson and others had been waiting to hear the results of the test, and the news came on the eve of the Potsdam Conference. Germany, their competitor in the race to develop an atomic bomb, had surrendered on May 7.
　Held from July 17 to August 2, 1945, the Potsdam Conference was convened by U.S. President Harry S. Truman, U.K. Prime Minister Winston Churchill (later replaced by Clement Atlee due to a change in government) and Soviet Union Communist Party General Secretary Joseph Stalin. On July 26, the Allied countries issued an ultimatum to Japan. Signed by the U.S., Britain and China, the so-called Potsdam Declaration called for Japan’s immediate and unconditional surrender.
　The Japanese government was looking for a pretext to end the carnage, but Japanese Prime Minister Suzuki Kantaro, bowing to military leaders demanding a continuation of the war, announced on July 28 that Japan would “withhold comment (on the Potsdam Declaration) and push for a successful conclusion to the war.” The atomic bombs had only recently been developed, and no one in Japan even considered the possibility of their existence.
　The Allied countries interpreted Prime Minister Suzuki’s subtle expression “withhold comment” (mokusatsu, literally “kill by silence”) as an outright rejection of the Potsdam Declaration. On the basis of this apparent rejection and other factors, the U.S. proceeded to drop a uranium atomic bomb on Hiroshima (on August 6) and a plutonium atomic bomb on Nagasaki (on August 9).

2. Target Selection and Orders for the Atomic Bombings

The Manhattan Project began in response to fears that Germany might develop an atomic bomb, but the object of the plan to use the atomic bomb shifted to Japan after November 1944, when intelligence revealed Germany’s failure to produce a bomb. During talks at Hyde Park in London on September 18, 1944, U.S. President Franklin Roosevelt and U.K. Prime Minister Winston Churchill agreed on the use of atomic bombs against Japan.
　In March 1945, when the atomic bombs were nearing completion, authorities established the “Interim Committee” to advise President Truman and a corresponding scientific panel on issues related to the atomic bomb. Headed by U.S. Secretary of War Henry Stimson, the committee examined the use of atomic bombs from social, political and military perspectives and, in May the same year, unanimously agreed upon a memorandum expressing the following three points:

　1) That the weapon be used against Japan at the earliest opportunity
　2) That it be used without warning
　3) That it be used on a dual target, namely, a military installation or war plant surrounded by or adjacent to homes or other buildings most susceptible to damage 85

　With regard to this decision, Herbert Feis remarks that, “While some of the members felt uneasy, they remained silent at that decisive moment. Although there were concerns about possible repercussions from introducing the atomic bombs to the world in this way, they were outweighed by the demands of war.” 86
　Nevertheless, the agreement caused controversy among scientists participating in the Manhattan Project, particularly members of the Franck Committee chaired by the noted physicist Dr. James Franck. The Franck Committee issued a report opposing the use of atomic bombs, stating that “the military advantages and the saving of American lives, achieved by the sudden use of atomic bombs against Japan, may be overweighed by the ensuing loss of confidence and by a wave of horror and repulsion sweeping over the rest of the world and perhaps even dividing opinion at home.” 87 The Franck Committee also expressed fear about the danger of a nuclear arms race.
　Another group of 64 physicists later submitted a similar petition to President Truman, but it was still not enough to divert the tide of opinion calling for the use of atomic bombs. Writes American military historian Louis Morton:

By early July 1945, the stage had been set for the final decision. Stimson’s memorandum (comprising the three points noted earlier) had been approved in principle and on July 4 the British had given their consent to the use of the bomb against Japan. It remained only to decide on the terms and timing of the warning. 88

The “terms and timing of the warning” were decided by the successful test conducted on July 16 in the desert at Alamogordo, New Mexico. Moreover, since the Interim Committee stated in its memorandum that the weapon should be used against Japan “at the earliest opportunity,” the practical matter of selecting target cities took on a new urgency. In April 1945, the responsibility of studying this and other issues was handed to the “Target Committee,” a body established under the direction of General Leslie Groves.
　The committee convened for first time on April 27, 1945 and discussed a wide range of issues including bombing targets, strategies, technical factors and climate conditions. Warned beforehand that the committee proceedings were strictly confidential, members were informed of the criteria for target selection and given a list of 17 candidates, that is, Tōkyō Bay, Kawasaki, Yokohama, Nagoya, Ōsaka, Kōbe, Kyōto, Hiroshima, Kure, Yahata, Kokura, Shimonoseki, Yamaguchi, Kumamoto, Fukuoka, Nagasaki and Sasebo. The committee decided that any potential target that had already suffered heavy damage from air raids should be removed from the list.
　At the second meeting on May 10 and 11, the committee reduced the list to four cities: Kyōto, Hiroshima, Yokohama and Kokura. Niigata was also discussed as a possible target but eventually deleted. In response to the committee decision, military authorities issued an order on May 12 to cancel all conventional air raids on the four cities. A proposal to target the Imperial Palace in Tōkyō was also discussed at the second meeting, but the committee refrained from making any recommendations to that effect on the grounds that it was a matter best debated by those in charge of military policy.
　At this point in time, not even Major General Curtis LeMay, the Strategic Air Command leader who oversaw the large-scale air raids on Japan, had been informed about the atomic bombs, a fact that reveals the extent to which confidentially was maintained.
　At the third meeting of the Target Committee held on May 28, the members dropped Yokohama and Kokura from the list and reinstated Niigata, condensing the potential targets to the three cities of Kyōto, Hiroshima and Niigata. The U.S. forces promptly added Yokohama to their plan for large-scale conventional air raids, and the 21st Bomber Command reduced the city to ashes the very next day (May 29).
　By the beginning of July, the committee had revised the list of targets to include the relatively undamaged cities of Kyōto, Hiroshima, Kokura (reinstated for a second time) and Niigata. On July 21, the headquarters of the 20th Air Force Corps issued special orders for these four cities to be excluded from conventional air raids (their removal had been recommended on June 30 by the Joint Chiefs of Staff). In other words, military authorities were preserving the four cities in order to demonstrate the full power of the atomic bomb. Nagasaki was not yet on the target list but would replace Kyōto by July 22.
　News of the successful atomic bomb test at Alamogordo on July 16 was immediately relayed to President Truman at Potsdam. Secretary of War Henry Stimson, Army Chief of Staff George Marshall and Army Air Force Commander Henry Arnold, who had accompanied him to Germany, engaged in final discussions regarding the use of the atomic bomb on Japan. Similar discussions took place in Washington, D.C. among General Leslie Groves, director of the Manhattan Project, Carl Spaatz, commanding general of the U.S. Strategic Air Forces, and Thomas Handy, the army’s Acting Chief-of-Staff.
　Secretary of War Stimson was strongly opposed to the inclusion of Kyōto on the list of potential atomic bomb targets. On July 21, he received a message from the assistant chairman of the Interim Committee, George L. Harrison (who chaired the committee meeting in Washington during Stimson’s absence), requesting that Kyōto remain the leading candidate on the target list. This maneuver through Harrison was apparently a last-ditch effort by General Groves and others refusing to give in on the issue of Kyōto.
　Stimson, however, firmly rejected the request, and his decision resulted in the replacement of Kyōto with Nagasaki the next day. The plan proceeded accordingly thereafter, despite Groves’ insistence that Nagasaki was unsuitable as an atomic bomb target. Kyōto would continue to appear and disappear from the list over the following days, a fate shared by the city of Kokura.
　In Potsdam, President Truman apparently agreed with Stimson that the military value of Kyōto was not enough to merit the destruction of its precious architectural heritage as Japan’s ancient capital. This opinion, along with considerations regarding political affairs at home and abroad after the war, is said to have resulted in the removal of Kyōto from the list.
　Brigadier-general Thomas F. Farrell, deputy-commanding general of the Manhattan Engineering District, recalled the circumstances of the addition of Nagasaki to the list of atomic bomb targets as follows:

A meeting was held in General Handy’s room… One of the officers who had arrived with a message from General Arnold in Potsdam recommended that Nagasaki be added to the target list. Many other officers in the room disagreed with the idea. On behalf of Groves, I said that Nagasaki was too small for a large explosion. I continued that an atomic bomb would not demonstrate its explosive effect in the City, owing to the city’s long, narrow shape and mountainous terrain. I added that several air raids had already been carried out against the city, which would not be good in terms of atomic bombing effect measurement. 89

Despite the voices of dissent, however, Nagasaki remained on the final list of target cities.
　On July 24, following simultaneous deliberations among Stimson, Marshall and Arnold in Potsdam and Groves, Spaatz and Handy in Washington, D.C., an order signed by Thomas T. Handy, the Army’s Acting Chief of Staff, and approved by Stimson and Marshall was delivered to General Carl Spaatz, the commander of the U.S. Strategic Air Forces. Dated July 25, this order to use the atomic bomb against Japan arrived just as Spaatz was about to leave for Guam.
　The memorandum opened as follows: “The 509 Composite Group, 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki.” 90 Although mentioned last, Nagasaki was clearly designated as a candidate for the use of the atomic bomb.
　July 25 was the day before the announcement of the Potsdam Declaration, and by now the 509th Composite Group was already conducting exercises with “pumpkins” (to be discussed later) in preparation for the atomic bomb missions against Japan. The target cities of Hiroshima, Kokura, Niigata and Nagasaki had also been clearly finalized. Needless to say, the order to deliver the atomic bombs was issued on the basis of President Harry S. Truman’s personal directive.
　On July 31, several days after receiving the order, Spaatz sent a telegram from Guam to the Joint Chiefs of Staff in Washington D.C. suggesting that Nagasaki be deleted from the target list because “according to reports, there is a POW camp one mile north of the city’s center.” Thomas T. Handy responded with a dispatch stating that no changes were to be made or, in other words, that Nagasaki was to remain on the list. However he hurried to add that, if his conscience so demanded, General Spaatz might replace Nagasaki with Ōsaka, Amagasaki or Ōmuta, although these cities were not favorable targets.
　On August 1, the authorities deleted Niigata from the list of targets on the grounds that it was too small and too remote.
　In this way, the July 25 order issued by the Acting Chief of Staff designating Hiroshima, Kokura, Niigata and Nagasaki as target cities underwent a further alteration on the ground in Guam. The final decision to restrict the targets to Hiroshima, Kokura and Nagasaki was issued on August 2, in the form of Field Order No.13 for the 20th Air Force Corps on Guam. This document specifically ordered the 20th Air Force to strike a target in Japan on August 6, citing the urban and industrial districts of Hiroshima as the first target, the arsenal and urban area of Kokura as the second target, and the urban area of Nagasaki as the third target. The first atomic bomb was detonated over Hiroshima on August 6 in accordance with these orders.

　The Atomic Bombing Order
　July 25, 1945
　To: General Carl Spaatz
　　　　　Commanding General
　　　　　United States Army Strategic Air Forces

1. The 509 Composite Group, 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki. To carry military and civilian scientific personnel from the War Department to observe and record the effects of the explosion of the bomb, additional aircraft will accompany the airplane carrying the bomb. The observing planes will stay several miles distant from the point of impact of the bomb.

2. Additional bombs will be delivered on the above targets as soon as made ready by the project staff. Further instructions will be issued concerning targets other than those listed above.

3. Dissemination of any and all information concerning the use of the weapon against Japan is reserved to the Secretary of War and the President of the United States. No communiqués on the subject or releases of information will be issued by Commanders in the field without specific prior authority. Any news stories will be sent to the War Department for special clearance.

4. The foregoing directive is issued to you by direction and with the approval of the Secretary of War and of the Chief of Staff, U.S.A. It is desired that you personally deliver one copy of this directive to General MacArthur and one copy to Admiral Nimitz for their information.

THOS. T. HANDY. General, G.S.C
Acting Chief of Staff 91

3. Tinian Island and the Special Atomic Bombing Unit

Tinian, located approximately 2,400 km southeast of Tōkyō, is one of the Mariana Islands in the South Pacific. Like Saipan, it was placed under Japanese jurisdiction by the League of Nations in 1920 (in the wake of World War I). The island was the site of fierce combat during World War II. U.S. forces landed there on July 24, 1944 and after a desperate battle overwhelmed the more than 15,000 Japanese troops and local residents defending the island. Tinian is approximately seven kilometers from east to west and 17 kilometers from north to south, occupying an area of less than 100 km². The gently undulating terrain accommodated two important airfields known as “North Field” and “West Field.” The larger of the two, North Field, had four 2,600-meter runways.
　After the war, a signpost was erected to mark the spot associated with the atomic bombs. It was here that the uranium atomic bomb and plutonium atomic bomb intended for Hiroshima and Nagasaki, respectively, were assembled and loaded into the bomb bays, and from this very place where the B-29 bombers and surveillance aircraft departed for Japan.

Assembling and Training the Atomic Bombing Unit

During World War II, the United States government poured enormous amounts of money and manpower into the Manhattan Project, without ever consulting Congress, and pushed for the completion of the atomic bombs by the summer of 1945.

　The use of atomic bombs against Japan was formally decided on the basis of an agreement between U.S. President Theodore Roosevelt and British Prime Minister Winston Churchill at the Second Quebec Conference in September 1944 and confirmed by the Hyde Park Agreement of September 18.
　In actuality, however, the U.S. apparently decided upon the use of the bomb against Japan at an earlier date. This conjecture is underlined by the fact that, at the end of August 1944, the U.S. had already begun to secretly organize a special military unit assigned the duty of delivering the atomic bombs. This unit would come to be known as the “509th Composite Group, 20th Air Force” and the project to which it was devoted as “Operation Centerboard.” As the term “composite” indicates, the special unit was comprised of a number of different entities.

　Although the 509th Composite Group was officially activated on December 17, 1944, the bombing unit (flight squadron) forming the core of the operation was already engaged by September in elaborate training exercises at Wendover Army Airfield, a remote base in the middle of the Great Salt Lake Desert in Utah. This airfield was referred to by one of two codenames, Kingman or W-47.
　In addition to the bombing unit, the 509th Composite Group included maintenance, transportation and security units. It had its own command headquarters and was rigidly segregated from other groups. The group commander was Lt. Col. Paul W. Tibbets (promoted to colonel in January 1945), who would later pilot the aircraft that dropped the atomic bomb on Hiroshima.
　At the end of February 1945, with the fierce battle of Iwo Jima already underway, the U.S. forces decided to transfer the 509th Composite Group from Wendover Base to North Field on Tinian Island and to replace all of the group’s 15 B-29 bombers with new aircraft modified for the atomic bomb mission and outfitted with special bomb bays.

　The group’s ground support unit received transfer orders on April 26, 1945. Approximately 860 officers, noncommissioned officers and soldiers set off by ship from Seattle Harbor and landed at Tinian Island on May 30. The members of the bombing unit were already there by that time, having arrived between May 18 and 22 after departing from Wendover on three transport airplanes.
　By this time, the B-29s modified for the atomic bomb mission were reaching completion. The new bombers featured special bomb bays sturdy enough to hold the heavy and cumbersome atomic bombs. Moreover, to reduce weight, all armaments except the tail gun turret were removed. Pilots of the 509th Composite Group 393rd Bombardment Squadron flew the new bombers from the factory in Omaha, Nebraska to Wendover, and, after further test flights, departed for Tinian Island with other crewmembers. The 13 B-29s arrived on the island between June 11 and July 2, 1945.
　Major Charles W. Sweeney participated in the missions to both Hiroshima and Nagasaki and commanded the B-29 that dropped the atomic bomb on the latter. The following are excerpts from his memoir chronicling the experiences of the 509th Composite Group and the conditions at the base on Tinian Island.

The B-29s started their long flights to Tinian Island during the first week of June. My crew and I were among the last to leave the windswept desert of Wendover… and then on to the Marianas and the island of Tinian.
　After getting clearance from the tower, I began my final approach from the west and landed on one of the four parallel 8,500-foot-long runways on North Field that ran east to west across the northern tip of Tinian. Literally overnight, naval construction battalions, the Seabees, had constructed these mammoth airstrips and ancillary facilities. These facilities constituted the largest airfield in the world at the time… Tinian is shaped much like the island of Manhattan – elongated, north to south. The streets on Tinian were laid out and named after the streets in Manhattan…
　Before we arrived, Tinian had been occupied by the 313th Bombardment Wing of the XXI Bomber Command, flying incendiary missions over Japan and dropping mines by parachute into the waters of Japan’s harbors to stop the flow of ships supplying Japanese troops. Our group was to be nowhere near the 313th on the island, however. The 509th was completely isolated within its own compound, connected by taxiways to North Field. The compound was enclosed by a high fence with a main gate that was guarded around the clock by sentries. The perimeter of the fence was patrolled by heavily armed MPs. Inside the security perimeter were our living quarters and offices, a series of Quonset huts connected by a network of roads. Our working areas were the flight lines, located two miles from our living quarters. This area contained the only windowless, air-conditioned buildings in the Pacific, where the Alberta and Manhattan scientists and technicians and the first Ordnance personnel were laboring. Here the various components of the bombs would be assembled. The actual bombs’ casings and electrical circuits were also kept in this area, awaiting the internal workings that would breath life into the weapons — uranium and plutonium firing mechanisms and cores. Anyone trying to gain access without proper clearance could be shot.

　At North Field, our airplanes were under the same degree of security. No one was allowed near our aircraft or the specially dug concrete loading pits. 92 Unauthorized personnel were also subject to being shot.
　The accommodations within our compound were the best on the island — and possibly in the entire Pacific… We attended the 313th Wing ground school to learn the particular operations in this theater, such as weather patterns, air-sea rescue procedures, and flight patterns in and around airfields. We did not, however, fly missions within the command, and our aircraft could not be reassigned to non-509th crews, regardless of the need. Our maintenance operation and vast resources were not subject to the jurisdiction of the wing commander or the island commander. We were untouchable. 93
　The other B-29 crews were flying into the teeth of the enemy every night, carrying maximum loads of bombs, often barely making it into the air to start a journey of thousands of miles round-trip… These brave men looked upon us as contributing nothing to the war effort. We had no mission they were aware of. From an objective point of view, I could sympathize with their disdain. We seemed destined to finish out the war training for an illusory mission.

Training Flights

　We got the green light to commence practice missions over the neighboring islands of Rota and Guguan, which were still occupied by the Japanese. Our forces had bypassed those islands because they possessed no strategic value and, with their supply routes cut off, posed no danger to our forces in the Marianas. The missions would give our crews an introduction to theater operations without exposing them to enemy antiaircraft fire. The last thing we needed was to lose one of our specially trained crews while it was dropping practice bombs on an irrelevant target.
　The airplanes on this mission would drop pumpkins 94 , but unlike the Wendover pumpkins, these would be filled with Torpex, an enhanced explosive with an enormous destructive yield for a conventional bomb. We would release from 30,000 feet and the explosion would allow us to spot where it hit, whereupon the crew would maintain course until it took vertical photos of its own damage. 95

It should be noted here that on June 30, after the completion of ground training, the members of the 509th Composite Group immediately began combat training flights. Flights with bomb-loaded aircraft were initiated on July 1.

　As a result of the American island-hopping strategy, a number of islands around Tinian escaped landings because they were deemed inconsequential to the course of the war. Among these were Rota (90 km south of Tinian) where Japanese defensive units had constructed a small runway, and Guguan, 260 km to the north. These two islands were frequently targeted for training attacks, as were the islands of Truk, Marcus and Iwo. The bombs used were 250 kg or 500 kg GPs (conventional gunpowder demolition bombs). Charles W. Sweeney remembers these events as follows:

After a series of runs we were authorized to bomb Truk and Marcus, where the Japanese had such limited antiaircraft batteries to throw up at us that they would have little or no effect. This provided our first combat conditions, even though these runs were still recorded as “practice” missions by the air force.
　On July 20 we were finally cleared to fly missions over Japan. The targets were Otso [sic], Taira, Fukashima [sic], Nagaoka, Toyama, and Tōkyō. With the exception of Tibbets and a handful of the men he’d brought in at Wendover, most of the members of the 393rd would be flying their first combat missions. Tibbets, Beahan, Ferebee, and Van Pelt had flown missions in Europe. Captain Fred Bock and Lieutenant Colonel Classen had seen tours of duty in the South Pacific. It would be my first combat over enemy territory. At long last, we were in the war.
　These missions over Japan would have the same profile as the real one, if it ever happened. Each airplane would carry a single pumpkin filled with [the high performance explosive] Torpex, drop it on a target, and then take vertical photographs of the damage. Although inflicting damage on the enemy would be welcomed, it was a collateral objective. We were dress-rehearsing for the big day. The crews would be navigating long-range over water to a primary city in heavily defended enemy territory and dropping the weapons visually from 30,000 feet on a specific enemy target. The target might be a factory or a military base or a railroad yard. The goals were accuracy and assessment…
　Each crew would be briefed on a secondary target and a tertiary target if the primary target could not be bombed because of weather or any other problem. If the secondary and tertiary targets were obscured, the pilot, on his own initiative, could drop on so-called targets of opportunity. The only prohibition in the theater was that under no circumstances were the Imperial Palace in Tōkyō, where the emperor resided, and the ancient city of Kyōto, a religious and cultural center for the Japanese, to be bombed… Also on the off-limits list were Hiroshima, Kokura, Nagasaki and Niigata for reasons that were not explained to us by Colonel Tibbets.

　The Torpex drops also had the effect of allowing the Japanese to get accustomed to seeing a single B-29, unescorted by fighter aircraft, drop a single bomb from 30,000 feet…
　There were two further prohibitions. Colonel Tibbets and I were never to fly together over Japan, and Tibbets was prohibited from flying any of these combat missions. His capture by the Japanese could jeopardize the entire Manhattan Project. Within the 509th, he was the only one who knew practically everything. 96

Flight Training with Mock Atomic Bombs (Pumpkins)

As Charles W. Sweeney points out, the crewmembers of the 393rd Bombardment Squadron of the 509th Composite Group gathered actual battle experience as a way to prepare for the anticipated day of the atomic bombing. To familiarize themselves with the geography of the main islands of Japan, they participated in attacks across the country employing the above-mentioned mock atomic bombs (pumpkins). These raids were launched from Tinian Island starting on July 20, which means that they predated the issuing of the Potsdam Declaration by six days. In other words, test runs for the atomic bombings were already being conducted in the airspace over the home islands of Japan when the ultimatum was issued.
　A total of 29 municipalities (some noted by Sweeney) in various parts of Japan became targets for attacks employing these mock atomic bombs. From July 20 to the end of the war, a total of 49 pumpkins were dropped.
　The experience and technical knowledge gained from these training missions would be put to use in the actual atomic bombings of Hiroshima and Nagasaki. Another result was the appointment of Major Sweeney to command the B-29 bomber on the mission to Nagasaki.
　Wherever possible, the crewmembers delivered the pumpkins in the same manner as the actual atomic bombs, approaching targets upwind at altitudes of approximately 8,900 meters (29,000 feet) and releasing the bombs after visual confirmation with a Norden bombsight. The pilots then made 150 to 155-degree diving turns into the tailwind to aid their escape. There was obviously no need to conduct this maneuver when dropping pumpkins; it was part of the training for the atomic bomb missions, when it would indeed be necessary.
　The pumpkins are said to have weighed five tons (10,000 pounds), 5,500 pounds of which was TNT. They may have been “mock” bombs, but these enormous replicas of the atomic bombs were still sufficiently powerful to inflict serious damage in the event of either a direct hit or near miss. However, a B-29 could only carry one bomb at a time, and thus the damage inflicted was negligible when they exploded off-target.
　Pumpkins were dropped in various parts of Japan over a four-day period prior to the atomic bombings of Hiroshima and Nagasaki (July 20, 24, 26 and 29). They were also dropped on August 14, five days after the atomic bombing of Nagasaki.

Arrival of the Atomic Bombs at Tinian

The disassembled parts of the atomic bombs were transported to Tinian on the heavy cruiser USS Indianapolis and C-54 transport planes and reached the island between July 26 and August 2, 1945. In his book Seven Hours to Zero, Joseph L. Marx writes as follows about this event:

The cruiser [the Indianapolis] transported a strange wooden crate, explicitly marked “Confidential, U.S. Government.” [Inside the box were three atomic bomb casings.] At the same time, the cruiser transported [two] big bucket-like objects, very securely chained to the deck. The objects were guarded by two armed security staff members; one of them kept an all-night vigil. None of the other crewmembers was aware of the buckets. As intended by the security agency, the general crewmembers were occupied with guarding the large “secret” crate…
　When the Indianapolis arrived at Tinian Island, a huge crane was placed alongside the cruiser, to unload the “secret” crate to a LST [landing ship tank]. While the crewmembers were watching the crate “play-acting” at the front-deck, the two security staff members with the heavy buckets quietly stepped off the stern, carefully placing the buckets in a launch and landing on Tinian Island. 97

The delivery of the atomic bomb parts was the final mission of the USS Indianapolis. On July 29, the Japanese submarine I-58 (commanded by Lt. Cmdr. Hashimoto Mochitsura) attacked the cruiser on its way to Leyte Island, sinking it with three direct torpedo hits and taking the lives of approximately 900 crewmembers.
　The guard units at the top-secret North Field base further tightened security measures after the atomic bomb parts arrived at Tinian. “The bomb storage area was encircled in barbed wire and heavily guarded with staff members armed with machine-guns. Even generals had to show their gate passes to enter the area.” 98
　The parts sent from the U.S. were reassembled in an air-conditioned ammunition warehouse at Tinian on August 1, and the atomic bomb was complete and ready for use the following day.
　The uranium bomb was 71 cm in diameter, 3.05 m in length and weighed approximately four tons. Because of its gun-barrel shape and the fact that it was the smaller of the two bombs completed at that point, it garnered the nickname “Little Boy.” This was the bomb destined to explode over Hiroshima. Due to unfavorable weather conditions, the atomic bomb mission was delayed until August 6.
　The 509th Composite Group received the top-secret command for the atomic bombing on August 2, the first such order in human history. The following is a summary of the field operation order issued by Air Force Headquarters on Guam:

Field Order No.13 of the 20th Air Force on Guam
　Date of issue: August 2, 1945
　Date of attack: August 6
　Targets:
(1) Primary target: the urban industrial area of Hiroshima
(2) Secondary target: Kokura Arsenal and urban area
(3) Tertiary target: Nagasaki urban area
Required Force
Attack force: Three aircraft
Standby Aircraft: One
Weather observation: Three aircraft; one dispatched to each target. If the attack planes encounter cloud cover at the primary target, the secondary or tertiary target can be selected.
Bombing Altitude: 8,500 m – 9,200 m
Calibrated Airspeed at Time of Bombing: 200 mph
- Only visual bombing will be accomplished. Strike force will pass sufficiently close to primary target to assure, before going on to secondary target, that visual bombing is not possible on the primary.
- No friendly aircraft, other than those listed herein, will be within a 50 mile area of any of the targets for this strike during a period four hours prior to and six hours subsequent to strike time. 99

　On August 2, when the above order was issued, C-54 transport planes carried the last parts of the plutonium atomic bomb from Los Alamos to Tinian Island.
　Meanwhile, crewmembers began to undergo training for delivery of the implosion-type plutonium bomb (the type used on Nagasaki). The experimental bombs used for these tests resembled the actual atomic bomb much more closely than the pumpkin bombs. Three test bombs were built (F-13, F-18 and F-33), the last of which was ready for use on August 5. Assembly of the second atomic bomb (F-31) reached completion on August 6. Measuring 1.52 m in diameter, 3.25 m in length and weighing approximately 4.5 tons, this bomb was ellipsoidal in shape and larger than the earlier uranium bomb due to the different internal structure. The plutonium bomb was nicknamed “Fat Man” because of its bulbous appearance.
　The second atomic bombing order, Field Order No.17 of the 20th Air Force Corps, was issued on August 8. The only difference between orders No.13 and No.17 was the designated dates and targets. Order No. 17 specified August 9 as the strike date and the Kokura Arsenal and urban area and Nagasaki urban area as the primary and secondary targets, respectively.
　It has been said that the original plan was to strike on August 11 but that the date was moved up to August 9 because of forecasts predicting unfavorable weather due to the westward movement of a typhoon that had developed to the southeast of Iwo Jima. Another theory put forth is that the second atomic bomb was dropped earlier than scheduled because the Soviet Union declared war on Japan on August 8.

The 509th Group’s Sortie from Tinian
Nagasaki Attack F31 (Sortie Order No. 39)
Operation Date: August 9, 1945

* Indicated in Japan Local Time

Aircraft Numbers	Winner Numbers	Aircraft Names	Pilots	Tasks	Take-off Time*
292	82		Marquardt	Weather observation	1:30
347	95		McKnight	Weather observation
297	77	Bockscar	Sweeney	Bombing	2:30100
353	89	The Great Artiste	Bock	Bombing observation
354	90	Big Stink	Hopkins	Bombing photography
298	83		Taylor	On alert at Iwo Jima
291	91			First standby aircraft
301	85			Second standby aircraft

4. Nagasaki Bombing Records

　Each flight unit assigned to the atomic bombing included three B-29 bombers: one loaded with an atomic bomb, one carrying measuring instruments, and one for observation and photography. The three aircraft deployed for the Nagasaki atomic bombing were Bockscar piloted by Major Charles W. Sweeney, The Great Artiste piloted by Captain Fred Bock, and Big Stink piloted by Major James Hopkins.

　Bockscar took off from Tinian Island at 3:49 a.m. (2:49 a.m. local time) on August 9, 1945. The 13 crewmembers were as follows: Major Charles W. Sweeney, commander; Captain Charles Donald Albury, co-pilot; Lieutenant Fred Olivi, reserve co-pilot; Commander Frederick L. Ashworth (USN), weaponeer; Lieutenant Philip Barnes, assistant weaponeer; Lieutenant Jacob Beser, radar countermeasures; Captain Raymond “Kermit” Beahan, bombardier; Master Sergeant John D. Kuharek, flight engineer; Captain James Van Pelt, navigator; Sergeant Albert Dehart, tail gunner; Staff Sergeant Edward Buckley, radar operator; Sergeant Abe Spitzer, radio operator; and Staff Sergeant Ray Gallagher, scanner operator. Except for Ashworth, all the crewmembers had undergone training for one year at the secret bases in Wendover, Utah and Salton Sea, California. The regimen included sharp, 155-degree diving turns within 30 seconds at altitudes of 9,000 m, as well as the visual dropping of “pumpkin bombs” (mock atomic bombs) from an altitude of 9,600 m.
　After leaving Tinian, Bockscar headed north to Iwo Jima, then west to Yakushima, a small island south of the main island of Kyūshū. The crew spotted The Great Artiste upon arrival in the airspace over Yakushima, but Big Stink failed to appear. At 9:56 a.m. (8:56 local time), after waiting for 40 minutes, Bockscar and The Great Artiste departed for the primary atomic bomb target of Kokura, an industrial center on the east coast of Kyūshū.
　Two weather planes had taken off earlier than the bombing unit in order to monitor conditions at the target sites. The initial reports stated that the weather was fine in both Kokura and Nagasaki, but by the time Bockscar reached Kokura, the city was obscured by smoke and haze. The neighboring city of Yahata had been bombed the day before, and smoke from that attack was floating in the sky over Kokura. The crew opened Bockscar’s bomb-bay doors and prepared for a visual drop while the plane circled over the city. With anti-aircraft fire increasing and several shells exploding close to The Great Artiste, the crew of the bombing unit made three runs over Kokura but decided to depart for Nagasaki, the secondary target.
　Major Charles W. Sweeney, commander of Bockscar, remembered the events as follows:

Nagasaki was another industrial base, home to two massive Mitsubishi armament plants. It was defended, but with far less concentration. I looked at the Nagasaki field orders: FIELD ORDERS, NUMBER 17, 8 August 1945 – (2) Secondary target: 90.36 Nagasaki Urban Area.
　I located the coordinates on the aviation chart of Japan in front of me. Pressing my finger to the chart at Nagasaki, I saw that the city sat in two valleys split in the middle by a low range of hills. Although residential and commercial districts lay in the flat land surrounding the large harbor where Nagasaki’s shipbuilding and torpedo factories were located, maximum blast effect could be achieved only by dropping over this flat area below the range of hills…
　[On Bockscar, after deciding to abandon the primary target of Kokura, I] calmly directed our navigator, ‘Jim, give me the heading for Nagasaki.’
　For the second time in three days the city of Kokura had been spared.
　‘Roger.’ Van Pelt, who had already completed the calculations, responded quickly, giving me the heading. ‘Of course,’ he added, ‘this route will take us right over the Kyūshū fighter fields.’
　I couldn’t afford the extra fuel we’d consume if we swung out over the water, away from the bases. A direct line was the only way we could go. For anyone monitoring our progress from the ground, our direction and flight path would not be that difficult to figure out…
　‘We can’t avoid it, Jim,’ I said as I made the adjustments to put us on the precise heading. I was now an hour and a half behind schedule. The Fat Man was still resting in the bomb bay. I would have one shot to get this done when we arrived at Nagasaki. God only knew what awaited us there. Turning to Don Albury, I said, ‘Can any other goddamned thing go wrong?’
　I couldn’t believe my eyes. Nagasaki was obscured by 80 to 90% by cumulus clouds at 6,000 to 8,000 feet. A visual drop was improbable. We were approaching from the northwest and would arrive at the initial point in a few minutes. Kuharek confirmed again – we had enough fuel for a single bomb run.
　I called Commander Ashworth forward and laid out the situation. He was in charge of the bomb; I was in command of the aircraft. If we didn’t drop, we were out of options. We had about 300 gallons of fuel. If we stayed too long at Nagasaki by making a second bomb run, we might be forced to crash-land on the ground in Japan or in the ocean. If we didn’t get a visual on our first run and then depart, we’d have to dump the bomb into the ocean.
　I summoned up quickly. ‘We haven’t got the time or the fuel for more than one run. Let’s drop it by radar. I’ll guarantee we come within five hundred feet of the target.’ This was a commitment whose execution would be up to Ed Buckley, Kermit Beahan, and Jim Van Pelt. I didn’t have time to consult with them, but I had supreme confidence in my radar man, bombardier, and navigator.
　‘I don’t know, Chuck,’ Ashworth said.
　‘It’s better than dropping it into the ocean,’ I answered.
　‘Are you sure of the accuracy?” Ashworth pressed.
　‘I’ll take full responsibility for this,’ I assured him…
　From the IP, Van Pelt and Buckley started to coordinate the approach to the aiming point. The outline of the city appeared on the scopes in front of Van Pelt and Buckley. Buckley called out headings and precise closure rates to Beahan, who fed the data into the bombsight, all the while hoping for a break in the clouds.
　I reminded the crew to put on their goggles. I decided to leave mine off so I could see what I was doing.
　We were thirty seconds from the bomb’s release. The tone signal was activated and the bomb bay doors snapped open. Twenty-five seconds. Then Beahan yelled, ‘I’ve got it! I’ve got it!’
　I answered, ‘You own it.’
　Beahan had spotted a hole between the two great Mitsubishi armaments plants in the industrial valley. It was two miles north of the assigned aiming point and away from the residential area, now shielded by low hills beyond the coastal plain. He locked onto a racetrack reference point and made his adjustments, which were fed into the course direction indicator on my panel, from which I adjusted the flight panel as required. I was still flying the airplane manually to the release point. Earlier in the run, Beahan had caught a momentary glimpse of the assigned aiming point, but it would have disrupted the radar run if he took over. He reconsidered, hoping for a better view, which proved to be fortuitous for us and for the city below.
　‘Bombs away!” Beahan shouted, and then quickly corrected himself. ‘Bomb away.’
　At the moment of release the airplane lurched upward, suddenly ten thousand pounds lighter. It was 11:01 a.m. The bomb bay doors snapped shut. I took us into a steep, diving, 155-degree turn to the left, in a northeasterly direction, to get away from the blast.
　Time seemed suspended. As the seconds ticked by, I began to wonder if we had dropped a dud.
　Then suddenly the entire horizon burst into a super-brilliant white with an intense flash – more intense than Hiroshima. The light was blinding. A moment later, the first wave of super-heated air began hitting us with expected force. The shock waves were more severe than those at Hiroshima. But the airplane was still handling fine. Having been buffeted after the first atomic explosion, we knew it was not flak coming up from the ground. At Hiroshima there had been four or five shock waves of diminishing force, but these kept coming one after another with equal impact, maybe five in all.
　As I completed my turn, I could see a brownish, horizontal cloud enveloping the city below. The bomb had detonated at 1,890 feet, and in a millionth of a second compressed its core into a critical mass, releasing forces that were still incomprehensible. From the center of the brownish bile sprang a vertical column, boiling and bubbling up in those rainbow hues – purples, oranges, reds – colors whose brilliance I had seen only once before, and would never see again. The cloud was rising faster than that at Hiroshima. It seemed more intense, more angry. It was a mesmerizing sight, at once breathtaking and ominous.
　Although we were twelve miles away, it appeared to some crewmembers that the cloud was heading straight for us. At about 25,000 feet, an expanding mushroom cloud broke off, white and puffy, and continued to burst upward at accelerating speed, passing us at 30,000 feet and shooting up to at least 45,000 feet.
　I continued to bank around to allow Beahan to write his strike report. The blast damage seemed to be concentrated in the industrial Urakami Valley, where all we could see was a blanket of thick, dirty, brownish smoke with fires breaking through sporadically. The center of the downtown south of the ridge of hills separating the Urakami Valley from the coastal plain appeared untouched. The ridge of low-lying hills had shielded the residential area. Fires had broken out along the slopes of the hills. There was no question in my mind that the two Mitsubishi arms plants at Ōhashi and Morimachi and the Mitsubishi steelworks plants sitting in that valley, were no more. The bomb had exploded almost dead center among the three industrial giants. In a single stroke, they were gone.
　The mushroom cloud towered above us. The vertical cloud continued to rise with unbelievable rapidity, its colors continuously changing. Satisfied that we could make a preliminary strike report to Tinian, I told Abe Spitzer to transmit Beahan’s report, ‘Nagasaki bombed. Results good.’ When the transmission was received at Tinian, it was both a surprise and a relief. The military commanders at Tinian and Guam and in Washington had spent the previous two and half hours unsure about where we were or what we were doing. 101

The following is the first report sent to Tinian by Commander Frederick L. Ashworth, the weaponeer of the aircraft carrying the atomic bomb:

Bombed Nagasaki 090158Z visually with no fighter opposition and no flak. Results ‘technically successful’ but other factors involved make conference necessary before taking further steps. Visible effects about equal to Hiroshima. Trouble in airplane following delivery requires us to proceed to Okinawa. Fuel only to get to Okinawa.

Lieutenant Jacob Beser, in charge of Bockscar’s radar countermeasures, remembered his experience as follows:

It was a little before noon [11:00 a.m. local time] when we got over Nagasaki and it was ten-ten coverage, closed in completely. Commander Ashworth, as boss of the bomb, took the responsibility of ordering a radar run, as the fuel supply was too short to hang around there any longer. We started in completely on radar and just at the last couple of seconds we got a hole in the clouds. The visual run wasn’t long enough to make sure, but Capt. Kermit Beahan, the bombardier, thought he saw the aiming point and released the bomb.
　It turned out that we were a couple of miles off the briefed aiming point. We hit up the industrial valley instead of over on the other side of the ridge. Sweeney turned into the escape run, and we pulled up, waiting for the shock wave. I thought I knew what would happen, remembering Hiroshima. But this time we felt five distinct shock waves, probably from the blast echoing off Nagasaki’s hills. 102

Joseph L. Marx sheds further light on the atomic bomb mission in his book Nagasaki: The Necessary Bomb?:

The navigator, Captain Van Pelt, and the radarman, Sergeant Buckley, concentrated on their scopes, trying to bring the plane to the proper dropping point before releasing the bomb. They were about half a minute away.
　Suddenly there was a break in the clouds. Kermit Beahan, the bombardier, saw it and spoke up. ‘I’ve got it. I’ll take it now,’ he said, and did.
　The bomb-bay door opened. For the fourth time that day, the preliminary humming started. In the bombsight’s cross hairs, Beahan had the Mitsubishi Arms Manufacturing Plant, the secondary target. The automatic process started; abruptly the humming stopped and the plane jumped up, suddenly freed of the bomb’s weight.
　Beahan called out the traditional ‘Bombs away,’ and then, realizing this was not properly descriptive, amended it to ‘Bomb away.’ Sweeney swung the plane into the sharp diving turn practiced so often by the 509th’s bombers. It was 12:02 Tinian time; 11:02 Nagasaki time.
　Behind them, Captain Bock and The Great Artiste released the clusters of instruments and their parachutes and executed a similar turn in the reverse direction…
　Bock's Car [sic] and The Great Artiste, having survived the shock waves, turned and went back to check on the damage, taking pictures. As was the case with the men over Hiroshima, they were amazed at what they saw, although except for Commander Ashworth, Lieutenant Barnes, and Captain Olivi, the men on the strike plane had been aboard the instrument plane at the earlier detonation. The sight, even from six miles up, of the sudden death of a large portion of a city is one that cannot be believed even when seen. 103

The events on the ground at Nagasaki were immeasurably worse than anything observed during the experiment in the desert at Alamogordo, New Mexico.

5. The Aiming Point Specified in the Field Operation Order

The second atomic bomb was dropped in response to Field Order No. 17, issued by the 20th Air Force Headquarters on Guam. The order called for an attack on a target in Japan by the 20th Air Force on August 9, 1945. The first target was the Kokura Arsenal and urban area of Kokura; the second was the urban area of Nagasaki. Bockscar, the plane carrying the atomic bomb, flew from Tinian to Kokura, but poor visibility forced the crew to turn around and head for the secondary target of Nagasaki. Clouds also obscured Nagasaki, however, reducing the possibility of a visual drop on that target as well. Just as the crew prepared to switch to sighting by radar, the factory district of Urakami appeared through an opening in the clouds. It is a well-known fact that the Nagasaki atomic bomb, dropped by visual sighting, exploded over Matsuyama-machi, but a verification of the actual target designated in Field Order No. 17 is justified here.

Field Order No. 17 (Summarized)

Primary Target: 90.34-168 Kokura Arsenal and City
Aiming Point: 104082
Aiming Point Reference: XXI BomCom Litho-Mosaic (Kokura Arsenal: 90.34-168)
Checkpoint: Lat. 32º43’ N and Long. 132º33’ E [Okinoshima, Kōchi Prefecture]
Initial Point of Attack: Lat. 33º43’ N and Long. 131º38’ 30” E [Himeshima, Ōita Prefecture]
Evacuation Point: (executing a left turn of at least 150 degrees) Lat. 33º43’ N and Long. 131º38’ 30” E [same as initial point of attack]

Secondary Target: 90.36 Nagasaki Urban Area
Aiming Point: 114061
Aiming Point Reference: XXI BomCom Litho-Mosaic (Nagasaki Mitsubishi Steel Manufacturing and Arms Factory: 90.36-546)
Checkpoint: Lat. 32º25’ N and Long. 131º41’ E [cape located at the eastern end of Hyūga City, Miyazaki Prefecture]
Initial Point of Attack: Lat. 32º38’ N and Long. 130º39’ E [Shiranui-machi, Kumamoto Prefecture]
Disengagement Point: (executing a diving turn of at least 150 degrees to the left) Lat. 31º37’ N and Long.
131º28’ E [around Hizaki, Nichinan Seashore, Miyazaki Prefecture]

In the above order, the number 90 was used to designate Japan, 34 the area around Kokura and Yahata (part of modern-day Kitakyūshū City), 168 the Kokura Arsenal, and 36 Nagasaki.
　“XXI BomCom” refers to the 21st Bomber Command, forerunner of the 20th Air Force to which the 509th Composite Group belonged. The “Litho-Mosaic” (Nagasaki Mitsubishi Steel Manufacturing and Arms Factory: 90.36-546) was the map on which the coordinate point 114061 marked the target.
　The litho-mosaic is a map made up of a number of aerial photographs layered on top of each other. “Nagasaki Mitsubishi Steel Manufacturing and Arms Factory: 90.36-546 is the name of the specific map used by the U.S. Army in this case.
　The square litho-mosaic map of Nagasaki features coordinate points from 0 to 152 on four sides. The first three digits, 114 in this instance, indicate the horizontal axis, while the last three digits (061) indicate the vertical axis. The designated aiming point is the place where the vertical and horizontal lines intersect.
　The point marked on the litho-mosaic map is the area near Nigiwai Bridge, where the lower portion of Nakashima River runs through Nagasaki. More precisely, it is the area between Tokiwa Bridge and Nigiwai Bridge, both of which were used by streetcars crossing Nakashima River, just to the east of the hill bordered by Nagasaki City Hall and Nagasaki Prefectural Office. This was right in heart of downtown Nagasaki, at the center of the city’s historic district.
　If it had exploded over the aiming point according to Field Order No.17, the atomic bomb would have devastated the city center and administrative core, including the government office district, downtown shopping core, residential districts to the south and east, the railroad and port facilities, ships and vessels in the harbor, and the Mitsubishi factories on the opposite shore. The breakdown of administrative functions, especially at the prefectural and municipal government levels, would have severely hampered subsequent rescue and relief efforts and greatly compounded the impact of the atomic bombing.
　The atomic bomb exploded 3.4 km away from the designated aiming point, in the northern part of the city, but still caused colossal destruction, leaving approximately 74,000 persons dead and 75,000 injured among a total population of 240,000 and destroying some 18,000 houses. These figures alone reveal the enormous destructive power unleashed by nuclear weapons.

___________________________
80 Press release by the White House, August 6, 1945. (Harry S. Truman Library and Museum) ^
81 Shimamura Takashi, Hondo Kūshū (Air raids on the Japanese Mainland) ^
82 Herbert Feis, The Atomic Bomb and the End of World War II (Princeton University Press, 1967) ^
83 “War Department Release on New Mexico Test, July 16, 1945” (www.cddc.vt.edu/host/atomic/trinity/wd_press.html) ^
84 Joseph Laurance Marx, Seven Hours to Zero (Putnam, 1967) ^
85 Harry S. Truman Library and Museum (www.trumanlibrary.org/) ^
86 Herbert Feis, The Atomic Bomb and the End of World War II (Princeton University Press, 1967) ^
87 “The Franck Report,” June 11, 1945. (www.nuclearfiles.org) ^
88 Louis Morton, “The Decision to Use the Atomic Bomb” Foreign Affairs, Vol.XXV, No.2 (January, 1957). ^
89 Len Giovannitti, The Decision to Drop the Bomb (Methuen, 1967) ^
90 U.S. National Archives (NARA), Record Group 77, Records of the Office of the Chief of Engineers, Manhattan Engineer District, TS Manhattan Project File '42 to '46, Folder 5B. ^
91 NARA, RG 77, Records of the Office of the Chief of Engineers, Manhattan Engineer District, TS Manhattan Project File '42 to '46, Folder 5B. ^
92 The atomic bombs were small enough to fit in B-29 bomb bays but too large for the usual loading procedures. To solve this problem, they were placed in a large square pit, over which the airplane was pulled, and then lifted into the bomb bay. ^
93 Nevertheless, the 509th Composite Group officially belonged to the 313th Bombardment Wing. ^
94 The pumpkin was a ballistic bomb of the same shape and weight as “Fat Man,” the atomic bomb dropped on Nagasaki. This non-nuclear replica was referred to officially as the “10,000-pound L.C.,” L.C. standing for “light case.” Apparently derived from the fact that the practice bomb was painted orange and ellipsoidal in shape like a pumpkin, the term was used initially as a nickname among soldiers but eventually appeared even in official documents. ^
95 Charles W. Sweeney with James A. Antonucci and Marion K. Antonucci, War's End: An Eyewitness Account of America's Last Atomic Mission (Avon Books, 1997), p.135-40. ^
96 Ibid., p.140-2. ^
97 Joseph Laurance Marx ^
98 John Toland, Rising Sun: the Decline and Fall of the Japanese Empire, 1936-1945 (Random House, 1970) ^
99 http://www.beserfoundation.org/FO13.pdf ^
100 Charles W. Sweeney states that Bockscar took off at 2:56. In the U.S. Army’s final report on the Nagasaki atomic bombing, however, the time is listed as 2:49. ^
101 Charles W. Sweeney with James A. Antonucci and Marion K. Antonucci, War's End: An Eyewitness Account of America's Last Atomic Mission (Avon Books, 1997), p.195, 215-20. ^
102 Joseph L. Marx, Seven Hours to Zero (New York: Macfadden- Bartel, 1969), p.177. ^
103 Joseph L. Marx, Nagasaki: The Necessary Bomb? (New York: The Macmillan Co., 1971),
p.76, 83-4. ^

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