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The Atomic Bombings of Hiroshima and Nagasaki by The Manhattan Engineer District

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by The Manhattan Engineer District, June 29, 1946.


APPENDIX: Father Siemes' eyewitness account


This report describes the effects of the atomic bombs which were dropped on
the Japanese cities of Hiroshima and Nagasaki on August 6 and 9, 1945,
respectively. It summarizes all the authentic information that is
available on damage to structures, injuries to personnel, morale effect,
etc., which can be released at this time without prejudicing the security
of the United States.

This report has been compiled by the Manhattan Engineer District of the
United States Army under the direction of Major General Leslie R. Groves.
Special acknowledgement to those whose work contributed largely to this
report is made to:

The Special Manhattan Engineer District Investigating Group,
The United States Strategic Bombing Survey,
The British Mission to Japan, and

The Joint Atomic Bomb Investigating Group (Medical). and particularly to
the following individuals:

Col. Stafford L. Warren, Medical Corps, United States Army, for his
evaluation of medical data,

Capt. Henry L. Barnett, Medical Corps, United States Army, for his
evaluation of medical data,

Dr. R. Serber, for his comments on flash burn,

Dr. Hans Bethe, Cornell University, for his information of the nature of
atomic explosions,

Majors Noland Varley and Walter C. Youngs, Corps of Engineers, United
States Army, for their evaluation of physical damage to structures,

J. 0. Hirschfelder, J. L. Magee, M. Hull, and S. T. Cohen, of the Los
Alamos Laboratory, for their data on nuclear explosions,

Lieut. Col. David B. Parker, Corps of Engineers, United States Army, for
editing this report.


Statement by the President of the United States: "Sixteen hours ago an
American airplane dropped one bomb on Hiroshima, Japan, and destroyed its
usefulness to the enemy. That bomb had more power than 20,000 tons of
T.N.T. It had more than two thousand times the blast power of the British
Grand Slam, which is the largest bomb ever yet used in the history of

These fateful words of the President on August 6th, 1945, marked the first
public announcement of the greatest scientific achievement in history. The
atomic bomb, first tested in New Mexico on July 16, 1945, had just been
used against a military target.

On August 6th, 1945, at 8:15 A.M., Japanese time, a B-29 heavy bomber
flying at high altitude dropped the first atomic bomb on Hiroshima. More
than 4 square miles of the city were instantly and completely devastated.
66,000 people were killed, and 69,000 injured.

On August 9th, three days later, at 11:02 A.M., another B-29 dropped the
second bomb on the industrial section of the city of Nagasaki, totally
destroying 1 1/2 square miles of the city, killing 39,000 persons, and
injuring 25,000 more.

On August 10, the day after the atomic bombing of Nagasaki, the Japanese
government requested that it be permitted to surrender under the terms of
the Potsdam declaration of July 26th which it had previously ignored.


On August 11th, 1945, two days after the bombing of Nagasaki, a message was
dispatched from Major General Leslie R. Groves to Brigadier General Thomas
F. Farrell, who was his deputy in atomic bomb work and was representing him
in operations in the Pacific, directing him to organize a special Manhattan
Project Atomic Bomb Investigating Group.

This Group was to secure scientific, technical and medical intelligence in
the atomic bomb field from within Japan as soon as possible after the
cessation of hostilities. The mission was to consist of three groups:

1. Group for Hiroshima.
2. Group for Nagasaki.
3. Group to secure information concerning general Japanese activities in
the field of atomic bombs.

The first two groups were organized to accompany the first American troops
into Hiroshima and Nagasaki.

The primary purposes of the mission were as follows, in order of

1. To make certain that no unusual hazards were present in the bombed

2. To secure all possible information concerning the effects of the bombs,
both usual and unusual, and particularly with regard to radioactive
effects, if any, on the targets or elsewhere.

General Groves further stated that all available specialist personnel and
instruments would be sent from the United States, and that the Supreme
Allied Commander in the Pacific would be informed about the organization of
the mission.

On the same day, 11 August, the special personnel who formed the part of
the investigating group to be sent from the United States were selected and
ordered to California with instructions to proceed overseas at once to
accomplish the purposes set forth in the message to General Farrell. The
main party departed from Hamilton Field, California on the morning of 13
August and arrived in the Marianas on 15 August.

On 12 August the Chief of Staff sent the Theater Commander the following



General Farrell arrived in Yokohama on 30 August, with the Commanding
General of the 8th Army; Colonel Warren, who was Chief of the Radiological
Division of the District, arrived on 7 September. The main body of the
investigating group followed later. Preliminary inspections of Hiroshima
and Nagasaki were made on 8-9 and 13-14 September, respectively. Members
of the press had been enabled to precede General Farrell to Hiroshima.

The special groups spent 16 days in Nagasaki and 4 days in Hiroshima,
during which time they collected as much information as was possible under
their directives which called for a prompt report. After General Farrell
returned to the U.S. to make his preliminary report, the groups were headed
by Brigadier General J. B. Newman, Jr. More extensive surveys have been
made since that time by other agencies who had more time and personnel
available for the purpose, and much of their additional data has thrown
further light on the effects of the bombings. This data has been duly
considered in the making of this report.


On the day after the Hiroshima strike, General Farrell received
instructions from the War Department to engage in a propaganda campaign
against the Japanese Empire in connection with the new weapon and its use
against Hiroshima. The campaign was to include leaflets and any other
propaganda considered appropriate. With the fullest cooperation from
CINCPAC of the Navy and the United States Strategic Air Forces, he
initiated promptly a campaign which included the preparation and
distribution of leaflets, broadcasting via short wave every 15 minutes over
radio Saipan and the printing at Saipan and distribution over the Empire of
a Japanese language newspaper which included the description and
photographs of the Hiroshima strike.

The campaign proposed:

1. Dropping 16,000,000 leaflets in a period of 9 days on 47 Japanese cities
with population of over 100,000. These cities represented more than 40% of
the total population.

2. Broadcast of propaganda at regular intervals over radio Saipan.

3. Distribution of 500,000 Japanese language newspapers containing
stories and pictures of the atomic bomb attacks.

The campaign continued until the Japanese began their surrender
negotiations. At that time some 6,000,000 leaflets and a large number of
newspapers had been dropped. The radio broadcasts in Japanese had been
carried out at regular 15 minute intervals.


Both the Hiroshima and the Nagasaki atomic bombs exhibited similar effects.

The damages to man-made structures and other inanimate objects was the
result in both cities of the following effects of the explosions:

A. Blast, or pressure wave, similar to that of normal explosions.

B. Primary fires, i.e., those fires started instantaneously by the heat
radiated from the atomic explosion.

C. Secondary fires, i.e., those fires resulting from the collapse of
buildings, damage to electrical systems, overturning of stoves, and other
primary effects of the blast.

D. Spread of the original fires (B and C) to other structures.

The casualties sustained by the inhabitants of both cities were due to:

A. "Flash" burns, caused directly by the almost instantaneous radiation of
heat and light at the moment of the explosion.

B. Burns resulting from the fires caused by the explosion.

C. Mechanical injuries caused by collapse of buildings, flying debris,
and forceable hurling - about of persons struck by the blast pressure

D. Radiation injuries caused by the instantaneous penetrating radiation
(in many respects similar to excessive X-ray exposure) from the nuclear
explosion; all of these effective radiations occurred during the first
minute after initiation of the explosion, and nearly all occurred during
the first second of the explosion.

No casualties were suffered as a result of any persistent radioactivity of
fission products of the bomb, or any induced radioactivity of objects near
the explosion. The gamma radiations emitted by the nuclear explosion did
not, of course, inflict any damage on structures.

The number of casualties which resulted from the pure blast effect alone
(i.e., because of simple pressure) was probably negligible in comparison to
that caused by other effects.

The central portions of the cities underneath the explosions suffered
almost complete destruction. The only surviving objects were the frames of
a small number of strong reinforced concrete buildings which were not
collapsed by the blast; most of these buildings suffered extensive damage
from interior fires, had their windows, doors, and partitions knocked out,
and all other fixtures which were not integral parts of the reinforced
concrete frames burned or blown away; the casualties in such buildings near
the center of explosion were almost 100%. In Hiroshima fires sprang up
simultaneously all over the wide flat central area of the city; these fires
soon combined in an immense "fire storm" (high winds blowing inwards toward
the center of a large conflagration) similar to those caused by ordinary
mass incendiary raids; the resulting terrific conflagration burned out
almost everything which had not already been destroyed by the blast in a
roughly circular area of 4.4 square miles around the point directly under
the explosion (this point will hereafter in this report be referred to as
X). Similar fires broke out in Nagasaki, but no devastating fire storm
resulted as in Hiroshima because of the irregular shape of the city.

In both cities the blast totally destroyed everything within a radius of 1
mile from the center of explosion, except for certain reinforced concrete
frames as noted above. The atomic explosion almost completely destroyed
Hiroshima's identity as a city. Over a fourth of the population was killed
in one stroke and an additional fourth seriously injured, so that even if
there had been no damage to structures and installations the normal city
life would still have been completely shattered. Nearly everything was
heavily damaged up to a radius of 3 miles from the blast, and beyond this
distance damage, although comparatively light, extended for several more
miles. Glass was broken up to 12 miles.

In Nagasaki, a smaller area of the city was actually destroyed than in
Hiroshima, because the hills which enclosed the target area restricted the
spread of the great blast; but careful examination of the effects of the
explosion gave evidence of even greater blast effects than in Hiroshima.
Total destruction spread over an area of about 3 square miles. Over a
third of the 50,000 buildings in the target area of Nagasaki were destroyed
or seriously damaged. The complete destruction of the huge steel works and
the torpedo plant was especially impressive. The steel frames of all
buildings within a mile of the explosion were pushed away, as by a giant
hand, from the point of detonation. The badly burned area extended for 3
miles in length. The hillsides up to a radius of 8,000 feet were scorched,
giving them an autumnal appearance.


The following are the main conclusions which were reached after thorough
examination of the effects of the bombs dropped on Hiroshima and Nagasaki:

1. No harmful amounts of persistent radioactivity were present after the
explosions as determined by:

A. Measurements of the intensity of radioactivity at the time of the
investigation; and

B. Failure to find any clinical evidence of persons harmed by persistent

The effects of the atomic bombs on human beings were of three main types:

A. Burns, remarkable for (1) the great ground area over which they were
inflicted and (2) the prevalence of "flash" burns caused by the
instantaneous heat radiation.

B. Mechanical injuries, also remarkable for the wide area in which

C. Effects resulting from penetrating gamma radiation. The effects from
radiation were due to instantaneous discharge of radiation at the moment of
explosion and not to persistent radioactivity (of either fission products
or other substances whose radioactivity might have been induced by
proximity to the explosions).

The effects of the atomic bombs on structures and installations were of two

A. Destruction caused by the great pressure from the blast; and

B. Destruction caused by the fires, either started directly by the great
heat radiation, or indirectly through the collapse of buildings, wiring,

4. The actual tonnage of T.N.T. which would have caused the same blast
damage was approximately of the order of 20,000 tons.

5. In respect to their height of burst, the bombs performed exactly
according to design.

6. The bombs were placed in such positions that they could not have done
more damage from any alternative bursting point in either city.

7. The heights of burst were correctly chosen having regard to the type of
destruction it was desired to cause.

8. The information collected would enable a reasonably accurate prediction
to be made of the blast damage likely to be caused in any city where an
atomic explosion could be effected.


Some of the most frequent queries concerning the atomic bombs are those
dealing with the selection of the targets and the decision as to when the
bombs would be used.

The approximate date for the first use of the bomb was set in the fall of
1942 after the Army had taken over the direction of and responsibility for
the atomic bomb project. At that time, under the scientific assumptions
which turned out to be correct, the summer of 1945 was named as the most
likely date when sufficient production would have been achieved to make it
possible actually to construct and utilize an atomic bomb. It was
essential before this time to develop the technique of constructing and
detonating the bomb and to make an almost infinite number of scientific and
engineering developments and tests. Between the fall of 1942 and June
1945, the estimated probabilities of success had risen from about 60% to
above 90%; however, not until July 16, 1945, when the first full-scale test
took place in New Mexico, was it conclusively proven that the theories,
calculations, and engineering were correct and that the bomb would be

The test in New Mexico was held 6 days after sufficient material had become
available for the first bomb. The Hiroshima bomb was ready awaiting
suitable weather on July 31st, and the Nagasaki bomb was used as soon after
the Hiroshima bomb as it was practicable to operate the second mission.

The work on the actual selection of targets for the atomic bomb was begun
in the spring of 1945. This was done in close cooperation with the
Commanding General, Army Air Forces, and his Headquarters. A number of
experts in various fields assisted in the study. These included
mathematicians, theoretical physicists, experts on the blast effects of
bombs, weather consultants, and various other specialists. Some of the
important considerations were:

A. The range of the aircraft which would carry the bomb.

B. The desirability of visual bombing in order to insure the most
effective use of the bomb.

C. Probable weather conditions in the target areas.

D. Importance of having one primary and two secondary targets for each
mission, so that if weather conditions prohibited bombing the target there
would be at least two alternates.

E. Selection of targets to produce the greatest military effect on the
Japanese people and thereby most effectively shorten the war.

F. The morale effect upon the enemy.

These led in turn to the following:

A. Since the atomic bomb was expected to produce its greatest amount of
damage by primary blast effect, and next greatest by fires, the targets
should contain a large percentage of closely-built frame buildings and
other construction that would be most susceptible to damage by blast and

B. The maximum blast effect of the bomb was calculated to extend over an
area of approximately 1 mile in radius; therefore the selected targets
should contain a densely built-up area of at least this size.

C. The selected targets should have a high military strategic value.

D. The first target should be relatively untouched by previous bombing, in
order that the effect of a single atomic bomb could be determined.

The weather records showed that for five years there had never been two
successive good visual bombing days over Tokyo, indicating what might be
expected over other targets in the home islands. The worst month of the
year for visual bombing was believed to be June, after which the weather
should improve slightly during July and August and then become worse again
during September. Since good bombing conditions would occur rarely, the
most intense plans and preparations were necessary in order to secure
accurate weather forecasts and to arrange for full utilization of whatever
good weather might occur. It was also very desirable to start the raids
before September.



The city of Hiroshima is located on the broad, flat delta of the Ota River,
which has 7 channel outlets dividing the city into six islands which
project into Hiroshima Bay. The city is almost entirely flat and only
slightly above sea level; to the northwest and northeast of the city some
hills rise to 700 feet. A single hill in the eastern part of the city
proper about 1/2 mile long and 221 feet in height interrupted to some
extent the spreading of the blast damage; otherwise the city was fully
exposed to the bomb. Of a city area of over 26 square miles, only 7
square miles were completely built-up. There was no marked separation of
commercial, industrial, and residential zones. 75% of the population was
concentrated in the densely built-up area in the center of the city.

Hiroshima was a city of considerable military importance. It contained the
2nd Army Headquarters, which commanded the defense of all of southern
Japan. The city was a communications center, a storage point, and an
assembly area for troops. To quote a Japanese report, "Probably more than
a thousand times since the beginning of the war did the Hiroshima citizens
see off with cries of 'Banzai' the troops leaving from the harbor."

The center of the city contained a number of reinforced concrete buildings
as well as lighter structures. Outside the center, the area was congested
by a dense collection of small wooden workshops set among Japanese houses;
a few larger industrial plants lay near the outskirts of the city. The
houses were of wooden construction with tile roofs. Many of the industrial
buildings also were of wood frame construction. The city as a whole was
highly susceptible to fire damage.

Some of the reinforced concrete buildings were of a far stronger
construction than is required by normal standards in America, because of
the earthquake danger in Japan. This exceptionally strong construction
undoubtedly accounted for the fact that the framework of some of the
buildings which were fairly close to the center of damage in the city did
not collapse.

The population of Hiroshima had reached a peak of over 380,000 earlier in
the war but prior to the atomic bombing the population had steadily
decreased because of a systematic evacuation ordered by the Japanese
government. At the time of the attack the population was approximately
255,000. This figure is based on the registered population, used by the
Japanese in computing ration quantities, and the estimates of additional
workers and troops who were brought into the city may not be highly
accurate. Hiroshima thus had approximately the same number of people as
the city of Providence, R.I., or Dallas, Tex.


Nagasaki lies at the head of a long bay which forms the best natural harbor
on the southern Japanese home island of Kyushu. The main commercial and
residential area of the city lies on a small plain near the end of the bay.
Two rivers divided by a mountain spur form the two main valleys in which
the city lies. This mountain spur and the irregular lay-out of the city
tremendously reduced the area of destruction, so that at first glance
Nagasaki appeared to have been less devastated than Hiroshima.

The heavily build-up area of the city is confined by the terrain to less
than 4 square miles out of a total of about 35 square miles in the city as
a whole.

The city of Nagasaki had been one of the largest sea ports in southern
Japan and was of great war-time importance because of its many and varied
industries, including the production of ordnance, ships, military
equipment, and other war materials. The narrow long strip attacked was of
particular importance because of its industries.

In contrast to many modern aspects of Nagasaki, the residences almost
without exception were of flimsy, typical Japanese construction, consisting
of wood or wood-frame buildings, with wood walls with or without plaster,
and tile roofs. Many of the smaller industries and business establishments
were also housed in wooden buildings or flimsily built masonry buildings.
Nagasaki had been permitted to grow for many years without conforming to
any definite city zoning plan and therefore residences were constructed
adjacent to factory buildings and to each other almost as close as it was
possible to build them throughout the entire industrial valley.



Hiroshima was the primary target of the first atomic bomb mission. The
mission went smoothly in every respect. The weather was good, and the
crew and equipment functioned perfectly. In every detail, the attack was
carried out exactly as planned, and the bomb performed exactly as expected.

The bomb exploded over Hiroshima at 8:15 on the morning of August 6, 1945.
About an hour previously, the Japanese early warning radar net had detected
the approach of some American aircraft headed for the southern part of
Japan. The alert had been given and radio broadcasting stopped in many
cities, among them Hiroshima. The planes approached the coast at a very
high altitude. At nearly 8:00 A.M., the radar operator in Hiroshima
determined that the number of planes coming in was very small - probably
not more than three - and the air raid alert was lifted. The normal radio
broadcast warning was given to the people that it might be advisable to go
to shelter if B-29's were actually sighted, but no raid was expected beyond
some sort of reconnaissance. At 8:15 A.M., the bomb exploded with a
blinding flash in the sky, and a great rush of air and a loud rumble of
noise extended for many miles around the city; the first blast was soon
followed by the sounds of falling buildings and of growing fires, and a
great cloud of dust and smoke began to cast a pall of darkness over the

At 8:16 A.M., the Tokyo control operator of the Japanese Broadcasting
Corporation noticed that the Hiroshima station had gone off the air. He
tried to use another telephone line to reestablish his program, but it too
had failed. About twenty minutes later the Tokyo railroad telegraph center
realized that the main line telegraph had stopped working just north of
Hiroshima. From some small railway stops within ten miles of the city
there came unofficial and confused reports of a terrible explosion in
Hiroshima. All these reports were transmitted to the Headquarters of the
Japanese General Staff.

Military headquarters repeatedly tried to call the Army Control Station in
Hiroshima. The complete silence from that city puzzled the men at
Headquarters; they knew that no large enemy raid could have occurred, and
they knew that no sizeable store of explosives was in Hiroshima at that
time. A young officer of the Japanese General Staff was instructed to fly
immediately to Hiroshima, to land, survey the damage, and return to Tokyo
with reliable information for the staff. It was generally felt at
Headquarters that nothing serious had taken place, that it was all a
terrible rumor starting from a few sparks of truth.

The staff officer went to the airport and took off for the southwest.
After flying for about three hours, while still nearly 100 miles from
Hiroshima, he and his pilot saw a great cloud of smoke from the bomb. In
the bright afternoon, the remains of Hiroshima were burning.

Their plane soon reached the city, around which they circled in disbelief.
A great scar on the land, still burning, and covered by a heavy cloud of
smoke, was all that was left of a great city. They landed south of the
city, and the staff officer immediately began to organize relief measures,
after reporting to Tokyo.

Tokyo's first knowledge of what had really caused the disaster came from
the White House public announcement in Washington sixteen hours after
Hiroshima had been hit by the atomic bomb.


Nagasaki had never been subjected to large scale bombing prior to the
explosion of the atomic bomb there. On August 1st, 1945, however, a number
of high explosive bombs were dropped on the city. A few of these bombs hit
in the shipyards and dock areas in the southwest portion of the city.
Several of the bombs hit the Mitsubishi Steel and Arms Works and six bombs
landed at the Nagasaki Medical School and Hospital, with three direct hits
on buildings there. While the damage from these few bombs were relatively
small, it created considerable concern in Nagasaki and a number of people,
principally school children, were evacuated to rural areas for safety, thus
reducing the population in the city at the time of the atomic attack.

On the morning of August 9th, 1945, at about 7:50 A.M., Japanese time, an
air raid alert was sounded in Nagasaki, but the "All clear" signal was
given at 8:30. When only two B-29 superfortresses were sighted at 10:53
the Japanese apparently assumed that the planes were only on reconnaissance
and no further alarm was given. A few moments later, at 11:00 o'clock, the
observation B-29 dropped instruments attached to three parachutes and at
11:02 the other plane released the atomic bomb.

The bomb exploded high over the industrial valley of Nagasaki, almost
midway between the Mitsubishi Steel and Arms Works, in the south, and the
Mitsubishi-Urakami Ordnance Works (Torpedo Works), in the north, the two
principal targets of the city.

Despite its extreme importance, the first bombing mission on Hiroshima had
been almost routine. The second mission was not so uneventful. Again the
crew was specially trained and selected; but bad weather introduced some
momentous complications. These complications are best described in the
brief account of the mission's weaponeer, Comdr., now Capt., F. L.
Ashworth, U.S.N., who was in technical command of the bomb and was charged
with the responsibility of insuring that the bomb was successfully dropped
at the proper time and on the designated target. His narrative runs as

"The night of our take-off was one of tropical rain squalls, and flashes of
lightning stabbed into the darkness with disconcerting regularity. The
weather forecast told us of storms all the way from the Marianas to the
Empire. Our rendezvous was to be off the southeast coast of Kyushu, some
1500 miles away. There we were to join with our two companion observation
B-29's that took off a few minutes behind us. Skillful piloting and expert
navigation brought us to the rendezvous without incident.

"About five minutes after our arrival, we were joined by the first of our
B-29's. The second, however, failed to arrive, having apparently been
thrown off its course by storms during the night. We waited 30 minutes and
then proceeded without the second plane toward the target area.

"During the approach to the target the special instruments installed in the
plane told us that the bomb was ready to function. We were prepared to
drop the second atomic bomb on Japan. But fate was against us, for the
target was completely obscured by smoke and haze. Three times we attempted
bombing runs, but without success. Then with anti-aircraft fire bursting
around us and with a number of enemy fighters coming up after us, we headed
for our secondary target, Nagasaki.

"The bomb burst with a blinding flash and a huge column of black smoke
swirled up toward us. Out of this column of smoke there boiled a great
swirling mushroom of gray smoke, luminous with red, flashing flame, that
reached to 40,000 feet in less than 8 minutes. Below through the clouds we
could see the pall of black smoke ringed with fire that covered what had
been the industrial area of Nagasaki.

"By this time our fuel supply was dangerously low, so after one quick
circle of Nagasaki, we headed direct for Okinawa for an emergency landing
and refueling".


It was not at first apparent to even trained observers visiting the two
Japanese cities which of the two bombs had been the most effective.

In some respects, Hiroshima looked worse than Nagasaki. The fire damage in
Hiroshima was much more complete; the center of the city was hit and
everything but the reinforced concrete buildings had virtually disappeared.
A desert of clear-swept, charred remains, with only a few strong building
frames left standing was a terrifying sight.

At Nagasaki there were no buildings just underneath the center of
explosion. The damage to the Mitsubishi Arms Works and the Torpedo Works
was spectacular, but not overwhelming. There was something left to see,
and the main contours of some of the buildings were still normal.

An observer could stand in the center of Hiroshima and get a view of the
most of the city; the hills prevented a similar overall view in Nagasaki.
Hiroshima impressed itself on one's mind as a vast expanse of desolation;
but nothing as vivid was left in one's memory of Nagasaki.

When the observers began to note details, however, striking differences
appeared. Trees were down in both cities, but the large trees which fell
in Hiroshima were uprooted, while those in Nagasaki were actually snapped
off. A few reinforced concrete buildings were smashed at the center in
Hiroshima, but in Nagasaki equally heavy damage could be found 2,300 feet
from X. In the study of objects which gave definite clues to the blast
pressure, such as squashed tin cans, dished metal plates, bent or snapped
poles and like, it was soon evident that the Nagasaki bomb had been much
more effective than the Hiroshima bomb. In the description of damage which
follows, it will be noted that the radius for the amount of damage was
greater in Nagasaki than Hiroshima.


In considering the devastation in the two cities, it should be remembered
that the cities' differences in shape and topography resulted in great
differences in the damages. Hiroshima was all on low, flat ground, and was
roughly circular in shape; Nagasaki was much cut up by hills and mountain
spurs, with no regularity to its shape.

In Hiroshima almost everything up to about one mile from X was completely
destroyed, except for a small number (about 50) of heavily reinforced
concrete buildings, most of which were specially designed to withstand
earthquake shock, which were not collapsed by the blast; most of these
buildings had their interiors completely gutted, and all windows, doors,
sashes, and frames ripped out. In Nagasaki, nearly everything within 1/2
mile of the explosion was destroyed, including heavy structures. All
Japanese homes were destroyed within 1 1/2 miles from X.

Underground air raid shelters with earth cover roofs immediately below the
explosion had their roofs caved in; but beyond 1/2 mile from X they
suffered no damage.

In Nagasaki, 1500 feet from X high quality steel frame buildings were not
completely collapsed, but the entire buildings suffered mass distortion and
all panels and roofs were blown in.

In Nagasaki, 2,000 feet from X, reinforced concrete buildings with 10"
walls and 6" floors were collapsed; reinforced concrete buildings with 4"
walls and roofs were standing but were badly damaged. At 2,000 feet some
9" concrete walls were completely destroyed.

In Nagasaki, 3,500 feet from X, church buildings with 18" brick walls were
completely destroyed. 12" brick walls were severely cracked as far as
5,000 feet.

In Hiroshima, 4,400 feet from X, multi-story brick buildings were
completely demolished. In Nagasaki, similar buildings were destroyed to
5,300 feet.

In Hiroshima, roof tiles were bubbled (melted) by the flash heat out to
4,000 feet from X; in Nagasaki, the same effect was observed to 6,500 feet.

In Hiroshima, steel frame buildings were destroyed 4,200 feet from X, and
to 4,800 feet in Nagasaki.

In both cities, the mass distortion of large steel buildings was observed
out to 4,500 feet from X.

In Nagasaki, reinforced concrete smoke stacks with 8" walls, specially
designed to withstand earthquake shocks, were overturned up to 4,000 feet
from X.

In Hiroshima, steel frame buildings suffered severe structural damage up to
5,700 feet from X, and in Nagasaki the same damage was sustained as far as
6,000 feet.

In Nagasaki, 9" brick walls were heavily cracked to 5,000 feet, were
moderately cracked to 6,000 feet, and slightly cracked to 8,000 feet. In
both cities, light concrete buildings collapsed out to 4,700 feet.

In Hiroshima, multi-story brick buildings suffered structural damage up to
6,600 feet, and in Nagasaki up to 6,500 feet from X.

In both cities overhead electric installations were destroyed up to 5,500
feet; and trolley cars were destroyed up to 5,500 feet, and damaged to
10,500 feet.

Flash ignition of dry, combustible material was observed as far as 6,400
feet from X in Hiroshima, and in Nagasaki as far as 10,000 feet from X.

Severe damage to gas holders occured out to 6,500 feet in both cities.

All Japanese homes were seriously damaged up to 6,500 feet in Hiroshima,
and to 8,000 feet in Nagasaki. Most Japanese homes were damaged up to
8,000 feet in Hiroshima and 10,500 feet in Nagasaki.

The hillsides in Nagasaki were scorched by the flash radiation of heat as
far as 8,000 feet from X; this scorching gave the hillsides the appearance
of premature autumn.

In Nagasaki, very heavy plaster damage was observed in many buildings up to
9,000 feet; moderate damage was sustained as far as 12,000 feet, and light
damage up to 15,000 feet.

The flash charring of wooden telegraph poles was observed up to 9,500 feet
from X in Hiroshima, and to 11,000 feet in Nagasaki; some reports indicate
flash burns as far as 13,000 feet from X in both places.

Severe displacement of roof tiles was observed up to 8,000 feet in
Hiroshima, and to 10,000 feet in Nagasaki.

In Nagasaki, very heavy damage to window frames and doors was observed up
to 8,000 feet, and light damage up to 12,000 feet.

Roofs and wall coverings on steel frame buildings were destroyed out to
11,000 feet.

Although the sources of many fires were difficult to trace accurately, it
is believed that fires were started by primary heat radiation as far as
15,000 feet from X.

Roof damage extended as far as 16,000 feet from X in Hiroshima and in

The actual collapse of buildings was observed at the extreme range of
23,000 feet from X in Nagasaki.

Although complete window damage was observed only up to 12,000 feet from X,
some window damage occurred in Nagasaki up to 40,000 feet, and actual
breakage of glass occured up to 60,000 feet.

Heavy fire damage was sustained in a circular area in Hiroshima with a mean
radius of about 6,000 feet and a maximum radius of about 11,000 feet;
similar heavy damage occured in Nagasaki south of X up to 10,000 feet,
where it was stopped on a river course.

In Hiroshima over 60,000 of 90,000 buildings were destroyed or severely
damaged by the atomic bomb; this figure represents over 67% of the city's

In Nagasaki 14,000 or 27% of 52,000 residences were completely destroyed
and 5,40O, or 10% were half destroyed. Only 12% remained undamaged. This
destruction was limited by the layout of the city. The following is a
summary of the damage to buildings in Nagasaki as determined from a ground
survey made by the Japanese:

Destruction of Buildings and Houses Number Percentage
(Compiled by Nagasaki Municipality)

Total in Nagasaki (before atomic explosion) 50,000 100.0
Blasted (not burned) 2,652 5.3
Blasted and burned 11,494 23.0
Blasted and/or burned 14,146 28.3
Partially burned or blasted 5,441 10.9
Total buildings and houses destroyed 19,587 39.2
Undamaged 30,413 60.8

In Hiroshima, all utilities and transportation services were disrupted for
varying lengths of time. In general however services were restored about
as rapidly as they could be used by the depleted population. Through
railroad service was in order in Hiroshima on 8 August, and electric power
was available in most of the surviving parts on 7 August, the day after the
bombing. The reservoir of the city was not damaged, being nearly 2 miles
from X. However, 70,000 breaks in water pipes in buildings and dwellings
were caused by the blast and fire effects. Rolling transportation suffered
extensive damage. The damage to railroad tracks, and roads was
comparatively small, however. The electric power transmission and
distribution systems were badly wrecked. The telephone system was
approximately 80% damaged, and no service was restored until 15 August.

Despite the customary Japanese lack of attention to sanitation measures, no
major epidemic broke out in the bombed cities. Although the conditions
following the bombings makes this fact seem surprising, the experience of
other bombed cities in both Germany and Japan show Hiroshima and Nagasaki
not to be isolated cases.

The atomic explosion over Nagasaki affected an over-all area of
approximately 42.9 square miles of which about 8.5 square miles were water
and only about 9.8 square miles were built up, the remainder being
partially settled. Approximately 36% of the built up areas were seriously
damaged. The area most severely damaged had an average radius of about 1
mile, and covered about 2.9 square miles of which 2.4 were built up.

In Nagasaki, buildings with structural steel frames, principally the
Mitsubishi Plant as far as 6,000 feet from X were severely damaged; these
buildings were typical of wartime mill construction in America and Great
Britain, except that some of the frames were somewhat less substantial.
The damage consisted of windows broken out (100%), steel sashes ripped out
or bent, corrugated metal or corrugated asbestos roofs and sidings ripped
off, roofs bent or destroyed, roof trusses collapsed, columns bent and
cracked and concrete foundations for columns rotated. Damage to buildings
with structural steel frames was more severe where the buildings received
the effect of the blast on their sides than where the blast hit the ends of
buildings, because the buildings had more stiffness (resistance to negative
moment at the top of columns) in a longitudinal direction. Many of the
lightly constructed steel frame buildings collapsed completely while some
of the heavily constructed (to carry the weight of heavy cranes and loads)
were stripped of roof and siding, but the frames were only partially

The next most seriously damaged area in Nagasaki lies outside the 2.9
square miles just described, and embraces approximately 4.2 square miles of
which 29% was built up. The damage from blast and fire was moderate here,
but in some sections (portions of main business districts) many secondary
fires started and spread rapidly, resulting in about as much over-all
destruction as in areas much closer to X.

An area of partial damage by blast and fire lies just outside the one just
described and comprises approximately 35.8 square miles. Of this area,
roughly 1/6th was built up and 1/4th was water. The extent of damage
varied from serious (severe damage to roofs and windows in the main
business section of Nagasaki, 2.5 miles from X), to minor (broken or
occasionally broken windows at a distance of 7 miles southeast of X).

As intended, the bomb was exploded at an almost ideal location over
Nagasaki to do the maximum damage to industry, including the Mitsubishi
Steel and Arms Works, the Mitsubishi-Urakami Ordnance Works (Torpedo
Works), and numerous factories, factory training schools, and other
industrial establishments, with a minimum destruction of dwellings and
consequently, a minimum amount of casualties. Had the bomb been dropped
farther south, the Mitsubishi-Urakami Ordnance Works would not have been so
severely damaged, but the main business and residential districts of
Nagasaki would have sustained much greater damage casualties.

Calculations show that the structural steel and reinforced concrete frames
which survived the blast fairly close to X could not have withstood the
estimated peak pressures developed against the total areas presented by the
sides and roof of the buildings. The survival of these frames is explained
by the fact that they were not actually required to withstand the peak
pressure because the windows were quickly knocked out and roof and siding
stripped off thereby reducing total area and relieving the pressure. While
this saved the building frame, it permitted severe damage to building
interior and contents, and injuries to the building occupants. Buildings
without large panel openings through which the pressure could dissipate
were completely crushed, even when their frames were as strong as those
which survived.

The damage sustained by reinforced concrete buildings depended both on the
proximity to X and the type and strength of the reinforced concrete
construction. Some of the buildings with reinforced concrete frames also
had reinforced concrete walls, ceilings, and partitions, while others had
brick or concrete tile walls covered either with plaster or ornamental
stone, with partitions of metal, glass, and plaster. With the exception of
the Nagasaki Medical School and Hospital group, which was designed to
withstand earthquakes and was therefore of heavier construction than most
American structures, most of the reinforced concrete structures could be
classified only as fair, with concrete of low strength and density, with
many of the columns, beams, and slabs underdesigned and improperly
reinforced. These facts account for some of the structural failures which

In general, the atomic bomb explosion damaged all windows and ripped out,
bent, or twisted most of the steel window or door sashes, ripped doors from
hinges, damaged all suspended wood, metal, and plaster ceilings. The blast
concussion also caused great damage to equipment by tumbling and battering.
Fires generally of secondary origin consumed practically all combustible
material, caused plaster to crack off, burned all wooden trim, stair
covering, wooden frames of wooden suspended ceilings, beds, mattresses, and
mats, and fused glass, ruined all equipment not already destroyed by the
blast, ruined all electrical wiring, plumbing, and caused spalling of
concrete columns and beams in many of the rooms.

Almost without exception masonry buildings of either brick or stone within
the effective limits of the blast were severely damaged so that most of
them were flattened or reduced to rubble. The wreckage of a church,
approximately 1,800 feet east of X in Nagasaki, was one of the few masonry
buildings still recognizable and only portions of the walls of this
structure were left standing. These walls were extremely thick (about 2
feet). The two domes of the church had reinforced concrete frames and
although they were toppled, they held together as units.

Practically every wooden building or building with timber frame within 2.0
miles of X was either completely destroyed or very seriously damaged, and
significant damage in Nagasaki resulted as far as 3 miles from X. Nearly
all such buildings collapsed and a very large number were consumed by fire.

A reference to the various photographs depicting damage shows that although
most of the buildings within the effective limits of the blast were totally
destroyed or severely damaged, a large number of chimneys even close to X
were left standing, apparently uninjured by the concussion. One
explanation is that concrete chimneys are approximately cylindrical in
shape and consequently offer much less wind resistance than flat surfaces
such as buildings. Another explanation is that since the cities were
subject to typhoons the more modern chimneys were probably designed to
withstand winds of high velocity. It is also probable that most of the
recently constructed chimneys as well as the more modern buildings were
constructed to withstand the acceleration of rather severe earthquakes.
Since the bombs were exploded high in the air, chimneys relatively close to
X were subjected to more of a downward than a lateral pressure, and
consequently the overturning moment was much less than might have been

Although the blast damaged many bridges to some extent, bridge damage was
on the whole slight in comparison to that suffered by buildings. The
damage varied from only damaged railings to complete destruction of the
superstructure. Some of the bridges were wrecked and the spans were shoved
off their piers and into the river bed below by the force of the blast.
Others, particularly steel plate girder bridges, were badly buckled by the
blast pressure. None of the failures observed could be attributed to
inadequate design or structural weaknesses.

The roads, and railroad and street railway trackage sustained practically
no primary damage as a result of the explosion. Most of the damage to
railroads occurred from secondary causes, such as fires and damage to
bridges or other structures. Rolling stock, as well as automobiles,
trolleys, and buses were destroyed and burned up to a considerable distance
from X. Streets were impassable for awhile because of the debris, but they
were not damaged. The height of the bomb explosion probably explains the
absence of direct damage to railroads and roads.

A large part of the electric supply was interrupted by the bomb blast
chiefly through damage to electric substations and overhead transmission
systems. Both gas works in Nagasaki were severely damaged by the bomb.
These works would have required 6-7 months to get into operation. In
addition to the damage sustained by the electrical and gas systems, severe
damage to the water supply system was reported by the Japanese government;
the chief damage was a number of breaks in the large water mains and in
almost all of the distributing pipes in the areas which were affected by
the blast. Nagasaki was still suffering from a water shortage inside the
city six weeks after the atomic attack.

The Nagasaki Prefectural report describes vividly the effects of the bomb
on the city and its inhabitants:

"Within a radius of 1 kilometer from X, men and animals died almost
instantaneously and outside a radius of 1 kilometer and within a radius of
2 kilometers from X, some men and animals died instantly from the great
blast and heat but the great majority were seriously or superficially
injured. Houses and other structures were completely destroyed while fires
broke out everywhere. Trees were uprooted and withered by the heat.

"Outside a radius of 2 kilometers and within a radius of 4 kilometers from
X, men and animals suffered various degrees of injury from window glass and
other fragments scattered about by the blast and many were burned by the
intense heat. Dwellings and other structures were half damaged by blast.

"Outside a radius of 4 kilometers and within a radius of 8 kilometers
living creatures were injured by materials blown about by the blast; the
majority were only superficially wounded. Houses were only half or
partially damaged."

The British Mission to Japan interpreted their observations of the
destruction of buildings to apply to similar construction of their own as

A similar bomb exploding in a similar fashion would produce the following
effects on normal British houses:

Up to 1,000 yards from X it would cause complete collapse.

Up to 1 mile from X it would damage the houses beyond repair.

Up to 1.5 miles from X it would render them uninhabitable without extensive
repair, particularly to roof timbers.

Up to 2.5 miles from X it would render them uninhabitable until first-aid
repairs had been carried out.

The fire damage in both cities was tremendous, but was more complete in
Hiroshima than in Nagasaki. The effect of the fires was to change
profoundly the appearance of the city and to leave the central part bare,
except for some reinforced concrete and steel frames and objects such as
safes, chimney stacks, and pieces of twisted sheet metal. The fire damage
resulted more from the properties of the cities themselves than from those
of the bombs.

The conflagration in Hiroshima caused high winds to spring up as air was
drawn in toward the center of the burning area, creating a "fire storm".
The wind velocity in the city had been less than 5 miles per hour before
the bombing, but the fire-wind attained a velocity of 30-40 miles per hour.
These great winds restricted the perimeter of the fire but greatly added to
the damage of the conflagration within the perimeter and caused the deaths
of many persons who might otherwise have escaped. In Nagasaki, very severe
damage was caused by fires, but no extensive "fire storm" engulfed the
city. In both cities, some of the fires close to X were no doubt started
by the ignition of highly combustible material such as paper, straw, and
dry cloth, upon the instantaneous radiation of heat from the nuclear
explosion. The presence of large amounts of unburnt combustible materials
near X, however, indicated that even though the heat of the blast was very
intense, its duration was insufficient to raise the temperature of many
materials to the kindling point except in cases where conditions were
ideal. The majority of the fires were of secondary origin starting from
the usual electrical short-circuits, broken gas lines, overturned stoves,
open fires, charcoal braziers, lamps, etc., following collapse or serious
damage from the direct blast.

Fire fighting and rescue units were stripped of men and equipment. Almost
30 hours elapsed before any rescue parties were observable. In Hiroshima
only a handful of fire engines were available for fighting the ensuing
fires, and none of these were of first class type. In any case, however,
it is not likely that any fire fighting equipment or personnel or
organization could have effected any significant reduction in the amount of
damage caused by the tremendous conflagration.

A study of numerous aerial photographs made prior to the atomic bombings
indicates that between 10 June and 9 August 1945 the Japanese constructed
fire breaks in certain areas of the cities in order to control large scale
fires. In general these fire breaks were not effective because fires were
started at so many locations simultaneously. They appear, however, to have
helped prevent fires from spreading farther east into the main business and
residential section of Nagasaki.


There has been great difficulty in estimating the total casualties in the
Japanese cities as a result of the atomic bombing. The extensive
destruction of civil installations (hospitals, fire and police
department, and government agencies) the state of utter confusion
immediately following the explosion, as well as the uncertainty regarding
the actual population before the bombing, contribute to the difficulty of
making estimates of casualties. The Japanese periodic censuses are not
complete. Finally, the great fires that raged in each city totally
consumed many bodies.

The number of total casualties has been estimated at various times since
the bombings with wide discrepancies. The Manhattan Engineer District's
best available figures are:

Estimates of Casualties

Hiroshima Nagasaki
Pre-raid population 255,000 195,000
Dead 66,000 39,000
Injured 69,000 25,000
Total Casualties 135,000 64,000

The relation of total casualties to distance from X, the center of damage
and point directly under the air-burst explosion of the bomb, is of great
importance in evaluating the casualty-producing effect of the bombs. This
relationship for the total population of Nagasaki is shown in the table
below, based on the first-obtained casualty figures of the District:

Relation of Total Casualties to Distance from X

Distance Total Killed per
from X, feet Killed Injured Missing Casualties square mile
0 - 1,640 7,505 960 1,127 9,592 24,7OO
1,640 - 3,300 3,688 1,478 1,799 6,965 4,040
3,300 - 4,900 8,678 17,137 3,597 29,412 5,710
4,900 - 6,550 221 11,958 28 12,207 125
6,550 - 9,850 112 9,460 17 9,589 20

No figure for total pre-raid population at these different distances were
available. Such figures would be necessary in order to compute per cent
mortality. A calculation made by the British Mission to Japan and based on
a preliminary analysis of the study of the Joint Medical-Atomic Bomb
Investigating Commission gives the following calculated values for per cent
mortality at increasing distances from X:

Per-Cent Mortality at Various Distances

Distance from X, Per-cent Mortality
in feet
0 - 1000 93.0%
1000 - 2000 92.0
2000 - 3000 86.0
3000 - 4000 69.0
4000 - 5000 49.0
5000 - 6000 31.5
6000 - 7000 12.5
7000 - 8000 1.3
8000 - 9000 0.5
9000 - 10,000 0.0

It seems almost certain from the various reports that the greatest total
number of deaths were those occurring immediately after the bombing. The
causes of many of the deaths can only be surmised, and of course many
persons near the center of explosion suffered fatal injuries from more than
one of the bomb effects. The proper order of importance for possible
causes of death is: burns, mechanical injury, and gamma radiation. Early
estimates by the Japanese are shown in D below:

Cause of Immediate Deaths

City Cause of Death Per-cent of Total
Hiroshima Burns 60%
Falling debris 30
Other 10

Nagasaki Burns 95%
Falling debris 9
Flying glass 7
Other 7


The most striking difference between the explosion of an atomic bomb and
that of an ordinary T.N.T. bomb is of course in magnitude; as the President
announced after the Hiroshima attack, the explosive energy of each of the
atomic bombs was equivalent to about 20,000 tons of T.N.T.

But in addition to its vastly greater power, an atomic explosion has
several other very special characteristics. Ordinary explosion is a
chemical reaction in which energy is released by the rearrangement of the
atoms of the explosive material. In an atomic explosion the identity of
the atoms, not simply their arrangement, is changed. A considerable
fraction of the mass of the explosive charge, which may be uranium 235 or
plutonium, is transformed into energy. Einstein's equation, E = mc^2,
shows that matter that is transformed into energy may yield a total energy
equivalent to the mass multiplied by the square of the velocity of light.
The significance of the equation is easily seen when one recalls that the
velocity of light is 186,000 miles per second. The energy released when a
pound of T.N.T. explodes would, if converted entirely into heat, raise the
temperature of 36 lbs. of water from freezing temperature (32 deg F) to
boiling temperature (212 deg F). The nuclear fission of a pound of uranium
would produce an equal temperature rise in over 200 million pounds of

The explosive effect of an ordinary material such as T.N.T. is derived from
the rapid conversion of solid T.N.T. to gas, which occupies initially the
same volume as the solid; it exerts intense pressures on the surrounding
air and expands rapidly to a volume many times larger than the initial
volume. A wave of high pressure thus rapidly moves outward from the center
of the explosion and is the major cause of damage from ordinary high
explosives. An atomic bomb also generates a wave of high pressure which is
in fact of, much higher pressure than that from ordinary explosions; and
this wave is again the major cause of damage to buildings and other
structures. It differs from the pressure wave of a block buster in the
size of the area over which high pressures are generated. It also differs
in the duration of the pressure pulse at any given point: the pressure from
a blockbuster lasts for a few milliseconds (a millisecond is one thousandth
of a second) only, that from the atomic bomb for nearly a second, and was
felt by observers both in Japan and in New Mexico as a very strong wind
going by.

The next greatest difference between the atomic bomb and the T.N.T.
explosion is the fact that the atomic bomb gives off greater amounts of
radiation. Most of this radiation is "light" of some wave-length ranging
from the so-called heat radiations of very long wave length to the
so-called gamma rays which have wave-lengths even shorter than the X-rays
used in medicine. All of these radiations travel at the same speed; this,
the speed of light, is 186,000 miles per second. The radiations are
intense enough to kill people within an appreciable distance from the
explosion, and are in fact the major cause of deaths and injuries apart
from mechanical injuries. The greatest number of radiation injuries was
probably due to the ultra-violet rays which have a wave length slightly
shorter than visible light and which caused flash burn comparable to severe
sunburn. After these, the gamma rays of ultra short wave length are most
important; these cause injuries similar to those from over-doses of X-rays.

The origin of the gamma rays is different from that of the bulk of the
radiation: the latter is caused by the extremely high temperatures in the
bomb, in the same way as light is emitted from the hot surface of the sun
or from the wires in an incandescent lamp. The gamma rays on the other
hand are emitted by the atomic nuclei themselves when they are transformed
in the fission process. The gamma rays are therefore specific to the
atomic bomb and are completely absent in T.N.T. explosions. The light of
longer wave length (visible and ultra-violet) is also emitted by a T.N.T.
explosion, but with much smaller intensity than by an atomic bomb, which
makes it insignificant as far as damage is concerned.

A large fraction of the gamma rays is emitted in the first few microseconds
(millionths of a second) of the atomic explosion, together with neutrons
which are also produced in the nuclear fission. The neutrons have much
less damage effect than the gamma rays because they have a smaller
intensity and also because they are strongly absorbed in air and therefore
can penetrate only to relatively small distances from the explosion: at a
thousand yards the neutron intensity is negligible. After the nuclear
emission, strong gamma radiation continues to come from the exploded bomb.
This generates from the fission products and continues for about one minute
until all of the explosion products have risen to such a height that the
intensity received on the ground is negligible. A large number of beta
rays are also emitted during this time, but they are unimportant because
their range is not very great, only a few feet. The range of alpha
particles from the unused active material and fissionable material of the
bomb is even smaller.

Apart from the gamma radiation ordinary light is emitted, some of which is
visible and some of which is the ultra violet rays mainly responsible for
flash burns. The emission of light starts a few milliseconds after the
nuclear explosion when the energy from the explosion reaches the air
surrounding the bomb. The observer sees then a ball of fire which rapidly
grows in size. During most of the early time, the ball of fire extends as
far as the wave of high pressure. As the ball of fire grows its
temperature and brightness decrease. Several milliseconds after the
initiation of the explosion, the brightness of the ball of fire goes
through a minimum, then it gets somewhat brighter and remains at the order
of a few times the brightness of the sun for a period of 10 to 15 seconds
for an observer at six miles distance. Most of the radiation is given off
after this point of maximum brightness. Also after this maximum, the
pressure waves run ahead of the ball of fire.

The ball of fire rapidly expands from the size of the bomb to a radius of
several hundred feet at one second after the explosion. After this the
most striking feature is the rise of the ball of fire at the rate of about
30 yards per second. Meanwhile it also continues to expand by mixing with
the cooler air surrounding it. At the end of the first minute the ball has
expanded to a radius of several hundred yards and risen to a height of
about one mile. The shock wave has by now reached a radius of 15 miles and
its pressure dropped to less than 1/10 of a pound per square inch. The
ball now loses its brilliance and appears as a great cloud of smoke: the
pulverized material of the bomb. This cloud continues to rise vertically
and finally mushrooms out at an altitude of about 25,000 feet depending
upon meteorological conditions. The cloud reaches a maximum height of
between 50,000 and 70,000 feet in a time of over 30 minutes.

It is of interest to note that Dr. Hans Bethe, then a member of the
Manhattan Engineer District on loan from Cornell University, predicted the
existence and characteristics of this ball of fire months before the first
test was carried out.

To summarize, radiation comes in two bursts - an extremely intense one
lasting only about 3 milliseconds and a less intense one of much longer
duration lasting several seconds. The second burst contains by far the
larger fraction of the total light energy, more than 90%. But the first
flash is especially large in ultra-violet radiation which is biologically
more effective. Moreover, because the heat in this flash comes in such a
short time, there is no time for any cooling to take place, and the
temperature of a person's skin can be raised 50 degrees centigrade by the
flash of visible and ultra-violet rays in the first millisecond at a
distance of 4,000 yards. People may be injured by flash burns at even
larger distances. Gamma radiation danger does not extend nearly so far and
neutron radiation danger is still more limited.

The high skin temperatures result from the first flash of high intensity
radiation and are probably as significant for injuries as the total dosages
which come mainly from the second more sustained burst of radiation. The
combination of skin temperature increase plus large ultra-violet flux
inside 4,000 yards is injurious in all cases to exposed personnel. Beyond
this point there may be cases of injury, depending upon the individual
sensitivity. The infra-red dosage is probably less important because of its
smaller intensity.


The damage to man-made structures caused by the bombs was due to two
distinct causes: first the blast, or pressure wave, emanating from the
center of the explosion, and, second, the fires which were caused either by
the heat of the explosion itself or by the collapse of buildings containing
stoves, electrical fixtures, or any other equipment which might produce
what is known as a secondary fire, and subsequent spread of these fires.

The blast produced by the atomic bomb has already been stated to be
approximately equivalent to that of 20,000 tons of T.N.T. Given this
figure, one may calculate the expected peak pressures in the air, at
various distances from the center of the explosion, which occurred
following detonation of the bomb. The peak pressures which were calculated
before the bombs were dropped agreed very closely with those which were
actually experienced in the cities during the attack as computed by Allied
experts in a number of ingenious ways after the occupation of Japan.

The blast of pressure from the atomic bombs differed from that of ordinary
high explosive bombs in three main ways:

A. Downward thrust. Because the explosions were well up in the air, much
of the damage resulted from a downward pressure. This pressure of course
most largely effected flat roofs. Some telegraph and other poles
immediately below the explosion remained upright while those at greater
distances from the center of damage, being more largely exposed to a
horizontal thrust from the blast pressure waves, were overturned or tilted.
Trees underneath the explosion remained upright but had their branches
broken downward.

B. Mass distortion of buildings. An ordinary bomb can damage only a part
of a large building, which may then collapse further under the action of
gravity. But the blast wave from an atomic bomb is so large that it can
engulf whole buildings, no matter how great their size, pushing them over
as though a giant hand had given them a shove.

C. Long duration of the positive pressure pulse and consequent small
effect of the negative pressure, or suction, phase. In any explosion, the
positive pressure exerted by the blast lasts for a definite period of time
(usually a small fraction of a second) and is then followed by a somewhat
longer period of negative pressure, or suction. The negative pressure is
always much weaker than the positive, but in ordinary explosions the short
duration of the positive pulse results in many structures not having time
to fail in that phase, while they are able to fail under the more extended,
though weaker, negative pressure. But the duration of the positive pulse
is approximately proportional to the 1/3 power of the size of the explosive
charge. Thus, if the relation held true throughout the range in question,
a 10-ton T.N.T. explosion would have a positive pulse only about 1/14th as
long as that of a 20,000-ton explosion. Consequently, the atomic
explosions had positive pulses so much longer then those of ordinary
explosives that nearly all failures probably occurred during this phase,
and very little damage could be attributed to the suction which followed.

One other interesting feature was the combination of flash ignition and
comparative slow pressure wave. Some objects, such as thin, dry wooden
slats, were ignited by the radiated flash heat, and then their fires were
blown out some time later (depending on their distance from X) by the
pressure blast which followed the flash radiation.


Several ingenious methods were used by the various investigators to
determine, upon visiting the wrecked cities, what had actually been the
peak pressures exerted by the atomic blasts. These pressures were computed
for various distances from X, and curves were then plotted which were
checked against the theoretical predictions of what the pressures would be.
A further check was afforded from the readings obtained by the measuring
instruments which were dropped by parachute at each atomic attack. The
peak pressure figures gave a direct clue to the equivalent T.N.T. tonnage
of the atomic bombs, since the pressures developed by any given amount of
T.N.T. can be calculated easily.

One of the simplest methods of estimating the peak pressure is from
crushing of oil drums, gasoline cans, or any other empty thin metal vessel
with a small opening. The assumption made is that the blast wave pressure
comes on instantaneously, the resulting pressure on the can is more than
the case can withstand, and the walls collapse inward. The air inside is
compressed adiabatically to such a point that the pressure inside is less
by a certain amount than the pressure outside, this amount being the
pressure difference outside and in that the walls can stand in their
crumpled condition. The uncertainties involved are, first, that some air
rushes in through any opening that the can may have, and thus helps to
build up the pressure inside; and, second, that as the pressure outside
falls, the air inside cannot escape sufficiently fast to avoid the walls of
the can being blown out again to some extent. These uncertainties are such
that estimates of pressure based on this method are on the low side, i.e.,
they are underestimated.

Another method of calculating the peak-pressure is through the bending of
steel flagpoles, or lightning conductors, away from the explosion. It is
possible to calculate the drag on a pole or rod in an airstream of a
certain density and velocity; by connecting this drag with the strength of
the pole in question, a determination of the pressure wave may be obtained.

Still another method of estimating the peak pressure is through the
overturning of memorial stones, of which there are a great quantity in
Japan. The dimensions of the stones can be used along with known data on
the pressure exerted by wind against flat surfaces, to calculate the
desired figure.


There was no consistency in the long range blast damage. Observers often
thought that they had found the limit, and then 2,000 feet farther away
would find further evidence of damage.

The most impressive long range damage was the collapse of some of the
barracks sheds at Kamigo, 23,000 feet south of X in Nagasaki. It was
remarkable to see some of the buildings intact to the last details,
including the roof and even the windows, and yet next to them a similar
building collapsed to ground level.

The limiting radius for severe displacement of roof tiles in Nagasaki was
about 10,000 feet although isolated cases were found up to 16,000 feet.
In Hiroshima the general limiting radius was about 8,000 feet; however,
even at a distance of 26,000 feet from X in Hiroshima, some tiles were

At Mogi, 7 miles from X in Nagasaki, over steep hills over 600 feet high,
about 10% of the glass came out. In nearer, sequestered localities only 4
miles from X, no damage of any kind was caused. An interesting effect was
noted at Mogi; eyewitnesses said that they thought a raid was being made on
the place; one big flash was seen, then a loud roar, followed at several
second intervals by half a dozen other loud reports, from all directions.
These successive reports were obviously reflections from the hills
surrounding Mogi.


The ground shock in most cities was very light. Water pipes still carried
water and where leaks were visible they were mainly above ground.
Virtually all of the damage to underground utilities was caused by the
collapse of buildings rather than by any direct exertion of the blast
pressure. This fact of course resulted from the bombs' having been
exploded high in the air.


In any explosion, a certain amount of protection from blast may be gained
by having any large and substantial object between the protected object and
the center of the explosion. This shielding effect was noticeable in the
atomic explosions, just as in ordinary cases, although the magnitude of the
explosions and the fact that they occurred at a considerable height in the
air caused marked differences from the shielding which would have
characterized ordinary bomb explosions.

The outstanding example of shielding was that afforded by the hills in the
city of Nagasaki; it was the shielding of these hills which resulted in the
smaller area of devastation in Nagasaki despite the fact that the bomb used
there was not less powerful. The hills gave effective shielding only at
such distances from the center of explosion that the blast pressure was
becoming critical - that is, was only barely sufficient to cause collapse -
for the structure. Houses built in ravines in Nagasaki pointing well away
from the center of the explosion survived without damage, but others at
similar distances in ravines pointing toward the center of explosion were
greatly damaged. In the north of Nagasaki there was a small hamlet about
8,000 feet from the center of explosion; one could see a distinctive
variation in the intensity of damage across the hamlet, corresponding with
the shadows thrown by a sharp hill.

The best example of shielding by a hill was southeast of the center of
explosion in Nagasaki. The damage at 8,000 feet from X consisted of light
plaster damage and destruction of about half the windows. These buildings
were of European type and were on the reverse side of a steep hill. At the
same distance to the south-southeast the damage was considerably greater,
i.e., all windows and frames, doors, were damaged and heavy plaster damage
and cracks in the brick work also appeared. The contrast may be
illustrated also by the fact that at the Nagasaki Prefectural office at
10,800 feet the damage was bad enough for the building to be evacuated,
while at the Nagasaki Normal School to which the Prefectural office had
been moved, at the same distance, the damage was comparatively light.

Because of the height of the bursts no evidence was expected of the
shielding of one building by another, at least up to a considerable radius.
It was in fact difficult to find any evidence at any distance of such
shielding. There appeared to have been a little shielding of the building
behind the Administration Building of the Torpedo Works in Nagasaki, but
the benefits were very slight. There was also some evidence that the group
of buildings comprising the Medical School in Nagasaki did afford each
other mutual protection. On the whole, however, shielding of one building
by another was not noticeable.

There was one other peculiar type of shielding, best exhibited by the
workers' houses to the north of the torpedo plant in Nagasaki. These were
6,000 to 7,000 feet north of X. The damage to these houses was not nearly
as bad as those over a thousand feet farther away from the center of
explosion. It seemed as though the great destruction caused in the torpedo
plant had weakened the blast a little, and the full power was not restored
for another 1,000 feet or more.


As already stated, a characteristic feature of the atomic bomb, which is
quite foreign to ordinary explosives, is that a very appreciable fraction
of the energy liberated goes into radiant heat and light. For a
sufficiently large explosion, the flash burn produced by this radiated
energy will become the dominant cause of damage, since the area of burn
damage will increase in proportion to the energy released, whereas the area
of blast damage increases only with the two-thirds power of the energy.
Although such a reversal of the mechanism of damage was not achieved in the
Hiroshima and Nagasaki bombs, the effects of the flash were, however, very
evident, and many casualties resulted from flash burns. A discussion of
the casualties caused by flash burns will be given later; in this section
will be described the other flash effects which were observed in the two

The duration of the heat radiation from the bomb is so short, just a few
thousandths of a second, that there is no time for the energy falling on a
surface to be dissipated by thermal defusion; the flash burn is typically a
surface effect. In other words the surface of either a person or an object
exposed to the flash is raised to a very high temperature while immediately
beneath the surface very little rise in temperature occurs.

The flash burning of the surface of objects, particularly wooden objects,
occurred in Hiroshima up to a radius of 9,500 feet from X; at Nagasaki
burns were visible up to 11,000 feet from X. The charring and blackening
of all telephone poles, trees and wooden posts in the areas not destroyed
by the general fire occurred only on the side facing the center of
explosion and did not go around the corners of buildings or hills. The
exact position of the explosion was in fact accurately determined by taking
a number of sights from various objects which had been flash burned on one
side only.

To illustrate the effects of the flash burn, the following describes a
number of examples found by an observer moving northward from the center of
explosion in Nagasaki. First occurred a row of fence posts at the north
edge of the prison hill, at 0.3 miles from X. The top and upper part of
these posts were heavily charred. The charring on the front of the posts
was sharply limited by the shadow of a wall. This wall had however been
completely demolished by the blast, which of course arrived some time after
the flash. At the north edge of the Torpedo works, 1.05 miles from X,
telephone poles were charred to a depth of about 0.5 millimeters. A light
piece of wood similar to the flat side of an orange crate, was found
leaning against one of the telephone poles. Its front surface was charred
the same way as the pole, but it was evident that it had actually been
ignited. The wood was blackened through a couple of cracks and nail holes,
and around the edges onto the back surface. It seemed likely that this
piece of wood had flamed up under the flash for a few seconds before the
flame was blown out by the wind of the blast. Farther out, between 1.05
and 1.5 miles from the explosion, were many trees and poles showing a
blackening. Some of the poles had platforms near the top. The shadows
cast by the platforms were clearly visible and showed that the bomb had
detonated at a considerable height. The row of poles turned north and
crossed the mountain ridge; the flash burn was plainly visible all the way
to the top of the ridge, the farthest burn observed being at 2.0 miles from

Another striking effect of the flash burn was the autumnal appearance of
the bowl formed by the hills on three sides of the explosion point. The
ridges are about 1.5 miles from X. Throughout this bowl the foliage turned
yellow, although on the far side of the ridges the countryside was quite
green. This autumnal appearance of the trees extended to about 8,000 feet
from X.

However, shrubs and small plants quite near the center of explosion in
Hiroshima, although stripped of leaves, had obviously not been killed.
Many were throwing out new buds when observers visited the city.

There are two other remarkable effects of the heat radiated from the bomb
explosion. The first of these is the manner in which heat roughened the
surface of polished granite, which retained its polish only where it was
shielded from the radiated heat travelling in straight lines from the
explosion. This roughening by radiated heat caused by the unequal
expansion of the constituent crystals of the stone; for granite crystals
the melting temperature is about 600 deg centigrade. Therefore the depth
of roughening and ultimate flaking of the granite surface indicated the
depth to which this temperature occurred and helped to determine the
average ground temperatures in the instant following the explosion. This
effect was noted for distances about 1 1/2 times as great in Nagasaki as in

The second remarkable effect was the bubbling of roof tile. The size of
the bubbles and their extent was proportional to their nearness to the
center of explosion and also depended on how squarely the tile itself was
faced toward the explosion. The distance ratio of this effect between
Nagasaki and Hiroshima was about the same as for the flaking of polished

Various other effects of the radiated heat were noted, including the
lightening of asphalt road surfaces in spots which had not been protected
from the radiated heat by any object such as that of a person walking along
the road. Various other surfaces were discolored in different ways by the
radiated heat.

As has already been mentioned the fact that radiant heat traveled only in
straight lines from the center of explosion enabled observers to determine
the direction toward the center of explosion from a number of different
points, by observing the "shadows" which were cast by intervening objects
where they shielded the otherwise exposed surface of some object. Thus the
center of explosion was located with considerable accuracy. In a number of
cases these "shadows" also gave an indication of the height of burst of the
bomb and occasionally a distinct penumbra was found which enabled observers
to calculate the diameter of the ball of fire at the instant it was
exerting the maximum charring or burning effect.

One more interesting feature connected with heat radiation was the charring
of fabric to different degrees depending upon the color of the fabric. A
number of instances were recorded in which persons wearing clothing of
various colors received burns greatly varying in degree, the degree of burn
depending upon the color of the fabric over the skin in question. For
example a shirt of alternate light and dark gray stripes, each about 1/8 of
an inch wide, had the dark stripes completely burned out but the light
stripes were undamaged; and a piece of Japanese paper exposed nearly 1 1/2
miles from X had the characters which were written in black ink neatly
burned out.


Injuries to persons resulting from the atomic explosions were of the
following types:

A. Burns, from
1. Flash radiation of heat
2. Fires started by the explosions.
B. Mechanical injuries from collapse of buildings, flying debris, etc.
C. Direct effects of the high blast pressure, i.e., straight
D. Radiation injuries, from the instantaneous emission of gamma rays and

It is impossible to assign exact percentages of casualties to each of the
types of injury, because so many victims were injured by more than one
effect of the explosions. However, it is certain that the greater part of
the casualties resulted from burns and mechanical injures. Col. Warren,
one of America's foremost radioligists, stated it is probable that 7 per
cent or less of the deaths resulted primarily from radiation disease.

The greatest single factor influencing the occurrence of casualties was the
distance of the person concerned from the center of explosion.

Estimates based on the study of a selected group of 900 patients indicated
that total casualties occurred as far out as 14,000 feet at Nagasaki and
12,000 feet at Hiroshima.

Burns were suffered at a considerable greater distance from X than any
other type of injury, and mechanical injuries farther out than radiation

Medical findings show that no person was injured by radioactivity who was
not exposed to the actual explosion of the bombs. No injuries resulted
from persistent radioactivity of any sort.


Two types of burns were observed. These are generally differentiated as
flame or fire burn and so-called flash burn.

The early appearance of the flame burn as reported by the Japanese, and the
later appearance as observed, was not unusual.

The flash burn presented several distinctive features. Marked redness of
the affected skin areas appeared almost immediately, according to the
Japanese, with progressive changes in the skin taking place over a period
of a few hours. When seen after 50 days, the most distinctive feature of
these burns was their sharp limitation to exposed skin areas facing the
center of the explosion. For instance, a patient who had been walking in a
direction at right angles to a line drawn between him and the explosion,
and whose arms were swinging, might have burns only on the outside of the
arm nearest the center and on the inside of the other arm.

Generally, any type of shielding protected the skin against flash burns,
although burns through one, and very occasionally more, layers of clothing
did occur in patients near the center. In such cases, it was not unusual
to find burns through black but not through white clothing, on the same
patient. Flash burns also tended to involve areas where the clothes were
tightly drawn over the skin, such as at the elbows and shoulders.

The Japanese report the incidence of burns in patients surviving more than
a few hours after the explosion, and seeking medical attention, as high as
95%. The total mortalities due to burns alone cannot be estimated with any
degree of accuracy. As mentioned already, it is believed that the majority
of all the deaths occurred immediately. Of these, the Japanese estimate
that 75%, and most of the reports estimate that over 50%, of the deaths
were due to burns.

In general, the incidence of burns was in direct proportion to the distance
from X. However, certain irregularities in this relationship result in the
medical studies because of variations in the amount of shielding from flash
burn, and because of the lack of complete data on persons killed outright
close to X.

The maximum distance from X at which flash burns were observed is of
paramount interest. It has been estimated that patients with burns at
Hiroshima were all less than 7,500 feet from the center of the explosion at
the time of the bombing. At Nagasaki, patients with burns were observed
out to the remarkable distance of 13,800 feet.


The mechanical injuries included fractures, lacerations, contusions,
abrasions, and other effects to be expected from falling roofs, crumbling
walls, flying debris and glass, and other indirect blast effects. The
appearance of these various types of mechanical injuries was not remarkable
to the medical authorities who studied them.

It was estimated that patients with lacerations at Hiroshima were less than
10,600 feet from X, whereas at Nagasaki they extended as far as 12,200

The tremendous drag of wind, even as far as 1 mile from X, must have
resulted in many injuries and deaths. Some large pieces of a prison wall,
for example, were flung 80 feet, and many have gone 30 feet high before
falling. The same fate must have befallen many persons, and the chances of
a human being surviving such treatment are probably small.


No estimate of the number of deaths or early symptoms due to blast pressure
can be made. The pressures developed on the ground under the explosions
were not sufficient to kill more than those people very near the center of
damage (within a few hundred feet at most). Very few cases of ruptured ear
drums were noted, and it is the general feeling of the medical authorities
that the direct blast effects were not great. Many of the Japanese
reports, which are believed to be false, describe immediate effects such as
ruptured abdomens with protruding intestines and protruding eyes, but no
such results were actually traced to the effect of air pressure alone.


As pointed out in another section of this report the radiations from the
nuclear explosions which caused injuries to persons were primarily those
experienced within the first second after the explosion; a few may have
occurred later, but all occurred in the first minute. The other two
general types of radiation, viz., radiation from scattered fission products
and induced radioactivity from objects near the center of explosion, were
definitely proved not to have caused any casualties.

The proper designation of radiation injuries is somewhat difficult.
Probably the two most direct designations are radiation injury and gamma
ray injury. The former term is not entirely suitable in that it does not
define the type of radiation as ionizing and allows possible confusion with
other types of radiation (e.g., infra-red). The objection to the latter
term is that it limits the ionizing radiation to gamma rays, which were
undoubtedly the most important; but the possible contribution of neutron
and even beta rays to the biological effects cannot be entirely ignored.
Radiation injury has the advantage of custom, since it is generally
understood in medicine to refer to X-ray effect as distinguished from the
effects of actinic radiation. Accordingly, radiation injury is used in
this report to mean injury due only to ionizing radiation.

According to Japanese observations, the early symptons in patients
suffering from radiation injury closely resembled the symptons observed in
patients receiving intensive roentgen therapy, as well as those observed in
experimental animals receiving large doses of X-rays. The important
symptoms reported by the Japanese and observed by American authorities were
epilation (lose of hair), petechiae (bleeding into the skin), and other
hemorrhagic manifestations, oropharyngeal lesions (inflammation of the
mouth and throat), vomiting, diarrhea, and fever.

Epilation was one of the most spectacular and obvious findings. The
appearance of the epilated patient was typical. The crown was involved
more than the sides, and in many instances the resemblance to a monk's
tonsure was striking. In extreme cases the hair was totally lost. In some
cases, re-growth of hair had begun by the time patients were seen 50 days
after the bombing. Curiously, epilation of hair other than that of the
scalp was extremely unusual.

Petechiae and other hemorrhagic manifestations were striking findings.
Bleeding began usually from the gums and in the more seriously affected was
soon evident from every possible source. Petechiae appeared on the limbs
and on pressure points. Large ecchymoses (hemorrhages under the skin)
developed about needle punctures, and wounds partially healed broke down
and bled freely. Retinal hemorrhages occurred in many of the patients.
The bleeding time and the coagulation time were prolonged. The platelets
(coagulation of the blood) were characteristically reduced in numbers.

Nausea and vomiting appearing within a few hours after the explosion was
reported frequently by the Japanese. This usually had subsided by the
following morning, although occasionally it continued for two or three
days. Vomiting was not infrequently reported and observed during the
course of the later symptoms, although at these times it generally appeared
to be related to other manifestation of systemic reactions associated with

Diarrhea of varying degrees of severity was reported and observed. In the
more severe cases, it was frequently bloody. For reasons which are not yet
clear, the diarrhea in some cases was very persistent.

Lesions of the gums, and the oral mucous membrane, and the throat were
observed. The affected areas became deep red, then violacious in color;
and in many instances ulcerations and necrosis (breakdown of tissue)
followed. Blood counts done and recorded by the Japanese, as well as
counts done by the Manhattan Engineer District Group, on such patients
regularly showed leucopenia (low-white blood cell count). In extreme cases
the white blood cell count was below 1,000 (normal count is around 7,000).
In association with the leucopenia and the oropharyngeal lesions, a variety
of other infective processes were seen. Wounds and burns which were
healing adequately suppurated and serious necrosis occurred. At the same
time, similar ulcerations were observed in the larynx, bowels, and in
females, the gentalia. Fever usually accompanied these lesions.

Eye injuries produced by the atomic bombings in both cities were the
subject of special investigations. The usual types of mechanical injuries
were seen. In addition, lesions consisting of retinal hemorrhage and
exudation were observed and 75% of the patients showing them had other
signs of radiation injury.

The progress of radiation disease of various degrees of severity is shown
in the following table:

Summary of Radiation Injury
Clinical Symptoms and Findings

sion Most Severe Moderately Severe Mild
1. 1. Nausea and vomiting 1. Nausea and vomiting
2. after 1-2 hours. after 1-2 hours.
5. 2. Diarrhea
7. 4. Inflammation of the
mouth and throat
8. 5. Fever
9. 6. Rapid emaciation
11. (Mortality probably 2. Beginning epilation.
12. 100%)
18. 3. Loss of appetite
19. and general malaise. 1. Epilation
20. 4. Fever. 2. Loss of appetite
21. 5. Severe inflammation and malaise.
22. of the mouth and throat 3. Sore throat.
23. 4. Pallor.
24. 5. Petechiae
25. 6. Diarrhea
26. 7. Moderate emacia-
27. 6. Pallor. tion.
28. 7. Petechiae, diarrhea
29. and nose bleeds (Recovery unless com-
30. plicated by previous
31. 8. Rapid emaciation poor health or
Death super-imposed in-
(Mortality probably 50%) juries or infec-

It was concluded that persons exposed to the bombs at the time of
detonation did show effects from ionizing radiation and that some of these
patients, otherwise uninjured, died. Deaths from radiation began about a
week after exposure and reached a peak in 3 to 4 weeks. They practically
ceased to occur after 7 to 8 weeks.

Treatment of the burns and other physical injuries was carried out by the
Japanese by orthodox methods. Treatment of radiation effects by them
included general supportative measures such as rest and high vitamin and
caloric diets. Liver and calcium preparations were administered by
injection and blood transfusions were used to combat hemorrhage. Special
vitamin preparations and other special drugs used in the treatment of
similar medical conditions were used by American Army Medical Corps
officers after their arrival. Although the general measures instituted
were of some benefit no definite effect of any of the specific measures on
the course of the disease could be demonstrated. The use of sulfonamide
drugs by the Japanese and particularly of penicillin by the American
physicians after their arrival undoubtedly helped control the infections
and they appear to be the single important type of treatment which may have
effectively altered the earlier course of these patients.

One of the most important tasks assigned to the mission which investigated
the effects of the bombing was that of determining if the radiation effects
were all due to the instantaneous discharges at the time of the explosion,
or if people were being harmed in addition from persistent radioactivity.
This question was investigated from two points of view. Direct
measurements of persistent radioactivity were made at the time of the
investigation. From these measurements, calculations were made of the
graded radiation dosages, i.e., the total amount of radiation which could
have been absorbed by any person. These calculations showed that the
highest dosage which would have been received from persistent radioactivity
at Hiroshima was between 6 and 25 roentgens of gamma radiation; the highest
in the Nagasaki Area was between 30 and 110 roentgens of gamma radiation.
The latter figure does not refer to the city itself, but to a localized
area in the Nishiyama District. In interpreting these findings it must be
understood that to get these dosages, one would have had to remain at the
point of highest radioactivity for 6 weeks continuously, from the first
hour after the bombing. It is apparent therefore that insofar as could be
determined at Hiroshima and Nagasaki, the residual radiation alone could
not have been detrimental to the health of persons entering and living in
the bombed areas after the explosion.

The second approach to this question was to determine if any persons not in
the city at the time of the explosion, but coming in immediately afterwards
exhibited any symptoms or findings which might have been due to persistence
induced radioactivity. By the time of the arrival of the Manhattan
Engineer District group, several Japanese studies had been done on such
persons. None of the persons examined in any of these studies showed any
symptoms which could be attributed to radiation, and their actual blood
cell counts were consistently within the normal range. Throughout the
period of the Manhattan Engineer District investigation, Japanese doctors
and patients were repeatedly requested to bring to them any patients who
they thought might be examples of persons harmed from persistent
radioactivity. No such subjects were found.

It was concluded therefore as a result of these findings and lack of
findings, that although a measurable quantity of induced radioactivity was
found, it had not been sufficient to cause any harm to persons living in
the two cities after the bombings.


Exact figures on the thicknesses of various substances to provide complete
or partial protection from the effects of radiation in relation to the
distance from the center of explosion, cannot be released at this time.
Studies of collected data are still under way. It can be stated, however,
that at a reasonable distance, say about 1/2 mile from the center of
explosion, protection to persons from radiation injury can be afforded by a
layer of concrete or other material whose thickness does not preclude
reasonable construction.

Radiation ultimately caused the death of the few persons not killed by
other effects and who were fully exposed to the bombs up to a distance of
about 1/2 mile from X. The British Mission has estimated that people in
the open had a 50% chance of surviving the effects of radiation at 3/4 of a
mile from X.


In both Hiroshima and Nagasaki the tremendous scale of the disaster largely
destroyed the cities as entities. Even the worst of all other previous
bombing attacks on Germany and Japan, such as the incendiary raids on
Hamburg in 1943 and on Tokyo in 1945, were not comparable to the paralyzing
effect of the atomic bombs. In addition to the huge number of persons who
were killed or injuried so that their services in rehabilitation were not
available, a panic flight of the population took place from both cities
immediately following the atomic explosions. No significant reconstruction
or repair work was accomplished because of the slow return of the
population; at the end of November 1945 each of the cities had only about
140,000 people. Although the ending of the war almost immediately after
the atomic bombings removed much of the incentive of the Japanese people
toward immediate reconstruction of their losses, their paralysis was still
remarkable. Even the clearance of wreckage and the burning of the many
bodies trapped in it were not well organized some weeks after the bombings.
As the British Mission has stated, "the impression which both cities make
is of having sunk, in an instant and without a struggle, to the most
primitive level."

Aside from physical injury and damage, the most significant effect of the
atomic bombs was the sheer terror which it struck into the peoples of the
bombed cities. This terror, resulting in immediate hysterical activity and
flight from the cities, had one especially pronounced effect: persons who
had become accustomed to mass air raids had grown to pay little heed to
single planes or small groups of planes, but after the atomic bombings the
appearance of a single plane caused more terror and disruption of normal
life than the appearance of many hundreds of planes had ever been able to
cause before. The effect of this terrible fear of the potential danger
from even a single enemy plane on the lives of the peoples of the world in
the event of any future war can easily be conjectured.

The atomic bomb did not alone win the war against Japan, but it most
certainly ended it, saving the thousands of Allied lives that would have
been lost in any combat invasion of Japan.

Hiroshima -- August 6th, 1945

by Father John A. Siemes, professor of modern philosphy at Tokyo's Catholic

Up to August 6th, occasional bombs, which did no great damage, had fallen
on Hiroshima. Many cities roundabout, one after the other, were destroyed,
but Hiroshima itself remained protected. There were almost daily
observation planes over the city but none of them dropped a bomb. The
citizens wondered why they alone had remained undisturbed for so long a
time. There were fantastic rumors that the enemy had something special in
mind for this city, but no one dreamed that the end would come in such a
fashion as on the morning of August 6th.

August 6th began in a bright, clear, summer morning. About seven o'clock,
there was an air raid alarm which we had heard almost every day and a few
planes appeared over the city. No one paid any attention and at about
eight o'clock, the all-clear was sounded. I am sitting in my room at the
Novitiate of the Society of Jesus in Nagatsuke; during the past half year,
the philosophical and theological section of our Mission had been evacuated
to this place from Tokyo. The Novitiate is situated approximately two
kilometers from Hiroshima, half-way up the sides of a broad valley which
stretches from the town at sea level into this mountainous hinterland, and
through which courses a river. From my window, I have a wonderful view
down the valley to the edge of the city.

Suddenly--the time is approximately 8:14--the whole valley is filled by a
garish light which resembles the magnesium light used in photography, and I
am conscious of a wave of heat. I jump to the window to find out the cause
of this remarkable phenomenon, but I see nothing more than that brilliant
yellow light. As I make for the door, it doesn't occur to me that the
light might have something to do with enemy planes. On the way from the
window, I hear a moderately loud explosion which seems to come from a
distance and, at the same time, the windows are broken in with a loud
crash. There has been an interval of perhaps ten seconds since the flash
of light. I am sprayed by fragments of glass. The entire window frame has
been forced into the room. I realize now that a bomb has burst and I am
under the impression that it exploded directly over our house or in the
immediate vicinity.

I am bleeding from cuts about the hands and head. I attempt to get out of
the door. It has been forced outwards by the air pressure and has become
jammed. I force an opening in the door by means of repeated blows with my
hands and feet and come to a broad hallway from which open the various
rooms. Everything is in a state of confusion. All windows are broken and
all the doors are forced inwards. The bookshelves in the hallway have
tumbled down. I do not note a second explosion and the fliers seem to have
gone on. Most of my colleagues have been injured by fragments of glass. A
few are bleeding but none has been seriously injured. All of us have been
fortunate since it is now apparent that the wall of my room opposite the
window has been lacerated by long fragments of glass.

We proceed to the front of the house to see where the bomb has landed.
There is no evidence, however, of a bomb crater; but the southeast section
of the house is very severely damaged. Not a door nor a window remains.
The blast of air had penetrated the entire house from the southeast, but
the house still stands. It is constructed in a Japanese style with a
wooden framework, but has been greatly strengthened by the labor of our
Brother Gropper as is frequently done in Japanese homes. Only along the
front of the chapel which adjoins the house, three supports have given way
(it has been made in the manner of Japanese temple, entirely out of wood.)

Down in the valley, perhaps one kilometer toward the city from us, several
peasant homes are on fire and the woods on the opposite side of the valley
are aflame. A few of us go over to help control the flames. While we are
attempting to put things in order, a storm comes up and it begins to rain.
Over the city, clouds of smoke are rising and I hear a few slight
explosions. I come to the conclusion that an incendiary bomb with an
especially strong explosive action has gone off down in the valley. A few
of us saw three planes at great altitude over the city at the time of the
explosion. I, myself, saw no aircraft whatsoever.

Perhaps a half-hour after the explosion, a procession of people begins to
stream up the valley from the city. The crowd thickens continuously. A
few come up the road to our house. We give them first aid and bring them
into the chapel, which we have in the meantime cleaned and cleared of
wreckage, and put them to rest on the straw mats which constitute the floor
of Japanese houses. A few display horrible wounds of the extremities and
back. The small quantity of fat which we possessed during this time of war
was soon used up in the care of the burns. Father Rektor who, before
taking holy orders, had studied medicine, ministers to the injured, but our
bandages and drugs are soon gone. We must be content with cleansing the

More and more of the injured come to us. The least injured drag the more
seriously wounded. There are wounded soldiers, and mothers carrying burned
children in their arms. From the houses of the farmers in the valley comes
word: "Our houses are full of wounded and dying. Can you help, at least by
taking the worst cases?" The wounded come from the sections at the edge of
the city. They saw the bright light, their houses collapsed and buried the
inmates in their rooms. Those that were in the open suffered instantaneous
burns, particularly on the lightly clothed or unclothed parts of the body.
Numerous fires sprang up which soon consumed the entire district. We now
conclude that the epicenter of the explosion was at the edge of the city
near the Jokogawa Station, three kilometers away from us. We are concerned
about Father Kopp who that same morning, went to hold Mass at the Sisters
of the Poor, who have a home for children at the edge of the city. He had
not returned as yet.

Toward noon, our large chapel and library are filled with the seriously
injured. The procession of refugees from the city continues. Finally,
about one o'clock, Father Kopp returns, together with the Sisters. Their
house and the entire district where they live has burned to the ground.
Father Kopp is bleeding about the head and neck, and he has a large burn on
the right palm. He was standing in front of the nunnery ready to go home.
All of a sudden, he became aware of the light, felt the wave of heat and a
large blister formed on his hand. The windows were torn out by the blast.
He thought that the bomb had fallen in his immediate vicinity. The
nunnery, also a wooden structure made by our Brother Gropper, still
remained but soon it is noted that the house is as good as lost because the
fire, which had begun at many points in the neighborhood, sweeps closer and
closer, and water is not available. There is still time to rescue certain
things from the house and to bury them in an open spot. Then the house is
swept by flame, and they fight their way back to us along the shore of the
river and through the burning streets.

Soon comes news that the entire city has been destroyed by the explosion
and that it is on fire. What became of Father Superior and the three other
Fathers who were at the center of the city at the Central Mission and
Parish House? We had up to this time not given them a thought because we
did not believe that the effects of the bomb encompassed the entire city.
Also, we did not want to go into town except under pressure of dire
necessity, because we thought that the population was greatly perturbed and
that it might take revenge on any foreigners which they might consider
spiteful onlookers of their misfortune, or even spies.

Father Stolte and Father Erlinghagen go down to the road which is still
full of refugees and bring in the seriously injured who have sunken by the
wayside, to the temporary aid station at the village school. There iodine
is applied to the wounds but they are left uncleansed. Neither ointments
nor other therapeutic agents are available. Those that have been brought
in are laid on the floor and no one can give them any further care. What
could one do when all means are lacking? Under those circumstances, it is
almost useless to bring them in. Among the passersby, there are many who
are uninjured. In a purposeless, insensate manner, distraught by the
magnitude of the disaster most of them rush by and none conceives the
thought of organizing help on his own initiative. They are concerned only
with the welfare of their own families. It became clear to us during these
days that the Japanese displayed little initiative, preparedness, and
organizational skill in preparation for catastrophes. They failed to carry
out any rescue work when something could have been saved by a cooperative
effort, and fatalistically let the catastrophe take its course. When we
urged them to take part in the rescue work, they did everything willingly,
but on their own initiative they did very little.

At about four o'clock in the afternoon, a theology student and two
kindergarten children, who lived at the Parish House and adjoining
buildings which had burned down, came in and said that Father Superior
LaSalle and Father Schiffer had been seriously injured and that they had
taken refuge in Asano Park on the river bank. It is obvious that we must
bring them in since they are too weak to come here on foot.

Hurriedly, we get together two stretchers and seven of us rush toward the
city. Father Rektor comes along with food and medicine. The closer we get
to the city, the greater is the evidence of destruction and the more
difficult it is to make our way. The houses at the edge of the city are
all severely damaged. Many have collapsed or burned down. Further in,
almost all of the dwellings have been damaged by fire. Where the city
stood, there is a gigantic burned-out scar. We make our way along the
street on the river bank among the burning and smoking ruins. Twice we are
forced into the river itself by the heat and smoke at the level of the

Frightfully burned people beckon to us. Along the way, there are many dead
and dying. On the Misasi Bridge, which leads into the inner city we are
met by a long procession of soldiers who have suffered burns. They drag
themselves along with the help of staves or are carried by their less
severely injured comrades...an endless procession of the unfortunate.

Abandoned on the bridge, there stand with sunken heads a number of horses
with large burns on their flanks. On the far side, the cement structure of
the local hospital is the only building that remains standing. Its
interior, however, has been burned out. It acts as a landmark to guide us
on our way.

Finally we reach the entrance of the park. A large proportion of the
populace has taken refuge there, but even the trees of the park are on fire
in several places. Paths and bridges are blocked by the trunks of fallen
trees and are almost impassable. We are told that a high wind, which may
well have resulted from the heat of the burning city, has uprooted the
large trees. It is now quite dark. Only the fires, which are still raging
in some places at a distance, give out a little light.

At the far corner of the park, on the river bank itself, we at last come
upon our colleagues. Father Schiffer is on the ground pale as a ghost. He
has a deep incised wound behind the ear and has lost so much blood that we
are concerned about his chances for survival. The Father Superior has
suffered a deep wound of the lower leg. Father Cieslik and Father
Kleinsorge have minor injuries but are completely exhausted.

While they are eating the food that we have brought along, they tell us of
their experiences. They were in their rooms at the Parish House--it was a
quarter after eight, exactly the time when we had heard the explosion in
Nagatsuke--when came the intense light and immediately thereafter the sound
of breaking windows, walls and furniture. They were showered with glass
splinters and fragments of wreckage. Father Schiffer was buried beneath a
portion of a wall and suffered a severe head injury. The Father Superior
received most of the splinters in his back and lower extremity from which
he bled copiously. Everything was thrown about in the rooms themselves,
but the wooden framework of the house remained intact. The solidity of the
structure which was the work of Brother Gropper again shone forth.

They had the same impression that we had in Nagatsuke: that the bomb had
burst in their immediate vicinity. The Church, school, and all buildings
in the immediate vicinity collapsed at once. Beneath the ruins of the
school, the children cried for help. They were freed with great effort.
Several others were also rescued from the ruins of nearby dwellings. Even
the Father Superior and Father Schiffer despite their wounds, rendered aid
to others and lost a great deal of blood in the process.

In the meantime, fires which had begun some distance away are raging even
closer, so that it becomes obvious that everything would soon burn down.
Several objects are rescued from the Parish House and were buried in a
clearing in front of the Church, but certain valuables and necessities
which had been kept ready in case of fire could not be found on account of
the confusion which had been wrought. It is high time to flee, since the
oncoming flames leave almost no way open. Fukai, the secretary of the
Mission, is completely out of his mind. He does not want to leave the
house and explains that he does not want to survive the destruction of his
fatherland. He is completely uninjured. Father Kleinsorge drags him out
of the house on his back and he is forcefully carried away.

Beneath the wreckage of the houses along the way, many have been trapped
and they scream to be rescued from the oncoming flames. They must be left
to their fate. The way to the place in the city to which one desires to
flee is no longer open and one must make for Asano Park. Fukai does not
want to go further and remains behind. He has not been heard from since.
In the park, we take refuge on the bank of the river. A very violent
whirlwind now begins to uproot large trees, and lifts them high into the
air. As it reaches the water, a waterspout forms which is approximately
100 meters high. The violence of the storm luckily passes us by. Some
distance away, however, where numerous refugees have taken shelter, many
are blown into the river. Almost all who are in the vicinity have been
injured and have lost relatives who have been pinned under the wreckage or
who have been lost sight of during the flight. There is no help for the
wounded and some die. No one pays any attention to a dead man lying

The transportation of our own wounded is difficult. It is not possible to
dress their wounds properly in the darkness, and they bleed again upon
slight motion. As we carry them on the shaky litters in the dark over
fallen trees of the park, they suffer unbearable pain as the result of the
movement, and lose dangerously large quantities of blood. Our rescuing
angel in this difficult situation is a Japanese Protestant pastor. He has
brought up a boat and offers to take our wounded up stream to a place where
progress is easier. First, we lower the litter containing Father Schiffer
into the boat and two of us accompany him. We plan to bring the boat back
for the Father Superior. The boat returns about one-half hour later and
the pastor requests that several of us help in the rescue of two children
whom he had seen in the river. We rescue them. They have severe burns.
Soon they suffer chills and die in the park.

The Father Superior is conveyed in the boat in the same manner as Father
Schiffer. The theology student and myself accompany him. Father Cieslik
considers himself strong enough to make his way on foot to Nagatsuke with
the rest of us, but Father Kleinsorge cannot walk so far and we leave him
behind and promise to come for him and the housekeeper tomorrow. From the
other side of the stream comes the whinny of horses who are threatened by
the fire. We land on a sand spit which juts out from the shore. It is
full of wounded who have taken refuge there. They scream for aid for they
are afraid of drowning as the river may rise with the sea, and cover the
sand spit. They themselves are too weak to move. However, we must press
on and finally we reach the spot where the group containing Father Schiffer
is waiting.

Here a rescue party had brought a large case of fresh rice cakes but there
is no one to distribute them to the numerous wounded that lie all about.
We distribute them to those that are nearby and also help ourselves. The
wounded call for water and we come to the aid of a few. Cries for help are
heard from a distance, but we cannot approach the ruins from which they
come. A group of soldiers comes along the road and their officer notices
that we speak a strange language. He at once draws his sword, screamingly
demands who we are and threatens to cut us down. Father Laures, Jr.,
seizes his arm and explains that we are German. We finally quiet him down.
He thought that we might well be Americans who had parachuted down. Rumors
of parachutists were being bandied about the city. The Father Superior who
was clothed only in a shirt and trousers, complains of feeling freezing
cold, despite the warm summer night and the heat of the burning city. The
one man among us who possesses a coat gives it to him and, in addition, I
give him my own shirt. To me, it seems more comfortable to be without a
shirt in the heat.

In the meantime, it has become midnight. Since there are not enough of us
to man both litters with four strong bearers, we determine to remove Father
Schiffer first to the outskirts of the city. From there, another group of
bearers is to take over to Nagatsuke; the others are to turn back in order
to rescue the Father Superior. I am one of the bearers. The theology
student goes in front to warn us of the numerous wires, beams and fragments
of ruins which block the way and which are impossible to see in the dark.
Despite all precautions, our progress is stumbling and our feet get tangled
in the wire. Father Kruer falls and carries the litter with him. Father
Schiffer becomes half unconscious from the fall and vomits. We pass an
injured man who sits all alone among the hot ruins and whom I had seen
previously on the way down.

On the Misasa Bridge, we meet Father Tappe and Father Luhmer, who have come
to meet us from Nagatsuke. They had dug a family out of the ruins of their
collapsed house some fifty meters off the road. The father of the family
was already dead. They had dragged out two girls and placed them by the
side of the road. Their mother was still trapped under some beams. They
had planned to complete the rescue and then to press on to meet us. At the
outskirts of the city, we put down the litter and leave two men to wait
until those who are to come from Nagatsuke appear. The rest of us turn
back to fetch the Father Superior.

Most of the ruins have now burned down. The darkness kindly hides the many
forms that lie on the ground. Only occasionally in our quick progress do
we hear calls for help. One of us remarks that the remarkable burned smell
reminds him of incinerated corpses. The upright, squatting form which we
had passed by previously is still there.

Transportation on the litter, which has been constructed out of boards,
must be very painful to the Father Superior, whose entire back is full of
fragments of glass. In a narrow passage at the edge of town, a car forces
us to the edge of the road. The litter bearers on the left side fall into
a two meter deep ditch which they could not see in the darkness. Father
Superior hides his pain with a dry joke, but the litter which is now no
longer in one piece cannot be carried further. We decide to wait until
Kinjo can bring a hand cart from Nagatsuke. He soon comes back with one
that he has requisitioned from a collapsed house. We place Father Superior
on the cart and wheel him the rest of the way, avoiding as much as possible
the deeper pits in the road.

About half past four in the morning, we finally arrive at the Novitiate.
Our rescue expedition had taken almost twelve hours. Normally, one could
go back and forth to the city in two hours. Our two wounded were now, for
the first time, properly dressed. I get two hours sleep on the floor; some
one else has taken my own bed. Then I read a Mass in gratiarum actionem,
it is the 7th of August, the anniversary of the foundation of our society.
Then we bestir ourselves to bring Father Kleinsorge and other acquaintances
out of the city.

We take off again with the hand cart. The bright day now reveals the
frightful picture which last night's darkness had partly concealed. Where
the city stood everything, as far as the eye could reach, is a waste of
ashes and ruin. Only several skeletons of buildings completely burned out
in the interior remain. The banks of the river are covered with dead and
wounded, and the rising waters have here and there covered some of the
corpses. On the broad street in the Hakushima district, naked burned
cadavers are particularly numerous. Among them are the wounded who are
still alive. A few have crawled under the burnt-out autos and trams.
Frightfully injured forms beckon to us and then collapse. An old woman and
a girl whom she is pulling along with her fall down at our feet. We place
them on our cart and wheel them to the hospital at whose entrance a
dressing station has been set up. Here the wounded lie on the hard floor,
row on row. Only the largest wounds are dressed. We convey another
soldier and an old woman to the place but we cannot move everybody who lies
exposed in the sun. It would be endless and it is questionable whether
those whom we can drag to the dressing station can come out alive, because
even here nothing really effective can be done. Later, we ascertain that
the wounded lay for days in the burnt-out hallways of the hospital and
there they died.

We must proceed to our goal in the park and are forced to leave the wounded
to their fate. We make our way to the place where our church stood to dig
up those few belongings that we had buried yesterday. We find them intact.
Everything else has been completely burned. In the ruins, we find a few
molten remnants of holy vessels. At the park, we load the housekeeper and
a mother with her two children on the cart. Father Kleinsorge feels strong
enough, with the aid of Brother Nobuhara, to make his way home on foot.
The way back takes us once again past the dead and wounded in Hakushima.
Again no rescue parties are in evidence. At the Misasa Bridge, there still
lies the family which the Fathers Tappe and Luhmer had yesterday rescued
from the ruins. A piece of tin had been placed over them to shield them
from the sun. We cannot take them along for our cart is full. We give
them and those nearby water to drink and decide to rescue them later. At
three o'clock in the afternoon, we are back in Nagatsuka.

After we have had a few swallows and a little food, Fathers Stolte, Luhmer,
Erlinghagen and myself, take off once again to bring in the family. Father
Kleinsorge requests that we also rescue two children who had lost their
mother and who had lain near him in the park. On the way, we were greeted
by strangers who had noted that we were on a mission of mercy and who
praised our efforts. We now met groups of individuals who were carrying
the wounded about on litters. As we arrived at the Misasa Bridge, the
family that had been there was gone. They might well have been borne away
in the meantime. There was a group of soldiers at work taking away those
that had been sacrificed yesterday.

More than thirty hours had gone by until the first official rescue party
had appeared on the scene. We find both children and take them out of the
park: a six-year old boy who was uninjured, and a twelve-year old girl who
had been burned about the head, hands and legs, and who had lain for thirty
hours without care in the park. The left side of her face and the left eye
were completely covered with blood and pus, so that we thought that she had
lost the eye. When the wound was later washed, we noted that the eye was
intact and that the lids had just become stuck together. On the way home,
we took another group of three refugees with us. They first wanted to
know, however, of what nationality we were. They, too, feared that we
might be Americans who had parachuted in. When we arrived in Nagatsuka, it
had just become dark.

We took under our care fifty refugees who had lost everything. The
majority of them were wounded and not a few had dangerous burns. Father
Rektor treated the wounds as well as he could with the few medicaments that
we could, with effort, gather up. He had to confine himself in general to
cleansing the wounds of purulent material. Even those with the smaller
burns are very weak and all suffered from diarrhea. In the farm houses in
the vicinity, almost everywhere, there are also wounded. Father Rektor
made daily rounds and acted in the capacity of a painstaking physician and
was a great Samaritan. Our work was, in the eyes of the people, a greater
boost for Christianity than all our work during the preceding long years.

Three of the severely burned in our house died within the next few days.
Suddenly the pulse and respirations ceased. It is certainly a sign of our
good care that so few died. In the official aid stations and hospitals, a
good third or half of those that had been brought in died. They lay about
there almost without care, and a very high percentage succumbed.
Everything was lacking: doctors, assistants, dressings, drugs, etc. In an
aid station at a school at a nearby village, a group of soldiers for
several days did nothing except to bring in and cremate the dead behind the

During the next few days, funeral processions passed our house from morning
to night, bringing the deceased to a small valley nearby. There, in six
places, the dead were burned. People brought their own wood and themselves
did the cremation. Father Luhmer and Father Laures found a dead man in a
nearby house who had already become bloated and who emitted a frightful
odor. They brought him to this valley and incinerated him themselves.
Even late at night, the little valley was lit up by the funeral pyres.

We made systematic efforts to trace our acquaintances and the families of
the refugees whom we had sheltered. Frequently, after the passage of
several weeks, some one was found in a distant village or hospital but of
many there was no news, and these were apparently dead. We were lucky to
discover the mother of the two children whom we had found in the park and
who had been given up for dead. After three weeks, she saw her children
once again. In the great joy of the reunion were mingled the tears for
those whom we shall not see again.

The magnitude of the disaster that befell Hiroshima on August 6th was only
slowly pieced together in my mind. I lived through the catastrophe and saw
it only in flashes, which only gradually were merged to give me a total
picture. What actually happened simultaneously in the city as a whole is
as follows: As a result of the explosion of the bomb at 8:15, almost the
entire city was destroyed at a single blow. Only small outlying districts
in the southern and eastern parts of the town escaped complete destruction.
The bomb exploded over the center of the city. As a result of the blast,
the small Japanese houses in a diameter of five kilometers, which
compressed 99% of the city, collapsed or were blown up. Those who were in
the houses were buried in the ruins. Those who were in the open sustained
burns resulting from contact with the substance or rays emitted by the
bomb. Where the substance struck in quantity, fires sprang up. These
spread rapidly.

The heat which rose from the center created a whirlwind which was effective
in spreading fire throughout the whole city. Those who had been caught
beneath the ruins and who could not be freed rapidly, and those who had
been caught by the flames, became casualties. As much as six kilometers
from the center of the explosion, all houses were damaged and many
collapsed and caught fire. Even fifteen kilometers away, windows were
broken. It was rumored that the enemy fliers had spread an explosive and
incendiary material over the city and then had created the explosion and
ignition. A few maintained that they saw the planes drop a parachute which
had carried something that exploded at a height of 1,000 meters. The
newspapers called the bomb an "atomic bomb" and noted that the force of the
blast had resulted from the explosion of uranium atoms, and that gamma rays
had been sent out as a result of this, but no one knew anything for certain
concerning the nature of the bomb.

How many people were a sacrifice to this bomb? Those who had lived through
the catastrophe placed the number of dead at at least 100,000. Hiroshima
had a population of 400,000. Official statistics place the number who had
died at 70,000 up to September 1st, not counting the missing ... and
130,000 wounded, among them 43,500 severely wounded. Estimates made by
ourselves on the basis of groups known to us show that the number of
100,000 dead is not too high. Near us there are two barracks, in each of
which forty Korean workers lived. On the day of the explosion, they were
laboring on the streets of Hiroshima. Four returned alive to one barracks
and sixteen to the other. 600 students of the Protestant girls' school
worked in a factory, from which only thirty to forty returned. Most of the
peasant families in the neighborhood lost one or more of their members who
had worked at factories in the city. Our next door neighbor, Tamura, lost
two children and himself suffered a large wound since, as it happened, he
had been in the city on that day. The family of our reader suffered two
dead, father and son; thus a family of five members suffered at least two
losses, counting only the dead and severely wounded. There died the Mayor,
the President of the central Japan district, the Commander of the city, a
Korean prince who had been stationed in Hiroshima in the capacity of an
officer, and many other high ranking officers. Of the professors of the
University, thirty-two were killed or severely injured. Especially hard
hit were the soldiers. The Pioneer Regiment was almost entirely wiped out.
The barracks were near the center of the explosion.

Thousands of wounded who died later could doubtless have been rescued had
they received proper treatment and care, but rescue work in a catastrophe
of this magnitude had not been envisioned; since the whole city had been
knocked out at a blow, everything which had been prepared for emergency
work was lost, and no preparation had been made for rescue work in the
outlying districts. Many of the wounded also died because they had been
weakened by under-nourishment and consequently lacked in strength to
recover. Those who had their normal strength and who received good care
slowly healed the burns which had been occasioned by the bomb. There were
also cases, however, whose prognosis seemed good who died suddenly. There
were also some who had only small external wounds who died within a week or
later, after an inflammation of the pharynx and oral cavity had taken
place. We thought at first that this was the result of inhalation of the
substance of the bomb. Later, a commission established the thesis that
gamma rays had been given out at the time of the explosion, following which
the internal organs had been injured in a manner resembling that consequent
upon Roentgen irradiation. This produces a diminution in the numbers of
the white corpuscles.

Only several cases are known to me personally where individuals who did not
have external burns later died. Father Kleinsorge and Father Cieslik, who
were near the center of the explosion, but who did not suffer burns became
quite weak some fourteen days after the explosion. Up to this time small
incised wounds had healed normally, but thereafter the wounds which were
still unhealed became worse and are to date (in September) still
incompletely healed. The attending physician diagnosed it as leucopania.
There thus seems to be some truth in the statement that the radiation had
some effect on the blood. I am of the opinion, however, that their
generally undernourished and weakened condition was partly responsible for
these findings. It was noised about that the ruins of the city emitted
deadly rays and that workers who went there to aid in the clearing died,
and that the central district would be uninhabitable for some time to come.
I have my doubts as to whether such talk is true and myself and others who
worked in the ruined area for some hours shortly after the explosion
suffered no such ill effects.

None of us in those days heard a single outburst against the Americans on
the part of the Japanese, nor was there any evidence of a vengeful spirit.
The Japanese suffered this terrible blow as part of the fortunes of war ...
something to be borne without complaint. During this, war, I have noted
relatively little hatred toward the allies on the part of the people
themselves, although the press has taken occasion to stir up such feelings.
After the victories at the beginning of the war, the enemy was rather
looked down upon, but when allied offensive gathered momentum and
especially after the advent of the majestic B-29's, the technical skill of
America became an object of wonder and admiration.

The following anecdote indicates the spirit of the Japanese: A few days
after the atomic bombing, the secretary of the University came to us
asserting that the Japanese were ready to destroy San Francisco by means of
an equally effective bomb. It is dubious that he himself believed what he
told us. He merely wanted to impress upon us foreigners that the Japanese
were capable of similar discoveries. In his nationalistic pride, he talked
himself into believing this. The Japanese also intimated that the
principle of the new bomb was a Japanese discovery. It was only lack of
raw materials, they said, which prevented its construction. In the
meantime, the Germans were said to have carried the discovery to a further
stage and were about to initiate such bombing. The Americans were reputed
to have learned the secret from the Germans, and they had then brought the
bomb to a stage of industrial completion.

We have discussed among ourselves the ethics of the use of the bomb. Some
consider it in the same category as poison gas and were against its use on
a civil population. Others were of the view that in total war, as carried
on in Japan, there was no difference between civilians and soldiers, and
that the bomb itself was an effective force tending to end the bloodshed,
warning Japan to surrender and thus to avoid total destruction. It seems
logical to me that he who supports total war in principle cannot complain
of war against civilians. The crux of the matter is whether total war in
its present form is justifiable, even when it serves a just purpose. Does
it not have material and spiritual evil as its consequences which far
exceed whatever good that might result? When will our moralists give us a
clear answer to this question?

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