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THE ATOMIC BOMBING OF HIROSHIMA (Hiroshima, Japan, August 6, 1945)
Events
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Dawn of the Atomic Era, 1945
-
The War Enters Its Final Phase, 1945
-
Debate Over How to Use the Bomb, Late Spring
1945
-
The Trinity Test, July 16, 1945
-
Safety and the Trinity Test, July 1945
-
Evaluations of Trinity, July 1945
-
Potsdam and the Final Decision to Bomb, July
1945
-
The Atomic Bombing of Hiroshima, August 6,
1945
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The Atomic Bombing of Nagasaki, August 9,
1945
-
Japan Surrenders, August 10-15, 1945
-
The Manhattan Project and the Second World War,
1939-1945
In the early morning hours of August 6, 1945, a B-29
bomber named Enola Gay took off from the island
of Tinian and headed north by northwest toward
Japan. The bomber's primary target was the
city of Hiroshima, located on the deltas
of southwestern Honshu Island facing the Inland Sea.
Hiroshima had a civilian population of almost 300,000 and
was an important military center, containing about 43,000
soldiers.
The bomber, piloted by the commander of the 509th
Composite Group, Colonel Paul Tibbets, flew at low
altitude on automatic pilot before climbing to 31,000 feet
as it neared the target area. At approximately 8:15
a.m. Hiroshima time the Enola Gay released
"Little Boy," its 9,700-pound
uranium gun-type bomb, over the
city. Tibbets immediately dove away to avoid the
anticipated shock wave. Forty-three seconds later, a
huge explosion lit the morning sky as
Little Boy detonated 1,900 feet above the city, directly
over a parade field where soldiers of the Japanese Second
Army were doing calisthenics. Though already eleven
and a half miles away, the Enola Gay was rocked
by the blast. At first, Tibbets thought he was
taking flak. After a second
shock wave (reflected from the ground) hit the plane, the
crew looked back at Hiroshima. "The city was
hidden by that awful cloud . . . boiling up, mushrooming,
terrible and incredibly tall," Tibbets
recalled. The yield of the
explosion was later estimated at 15 kilotons (the
equivalent of 15,000 tons of TNT).
On the ground moments before the blast it was a calm and
sunny Monday morning. An air raid alert from earlier
that morning had been called off after only a solitary
aircraft was seen (the weather plane), and by 8:15 the
city was alive with activity -- soldiers doing their
morning calisthenics, commuters on foot or on bicycles,
groups of women and children working
outside to clear firebreaks. Those closest to the
explosion died instantly, their bodies turned to black
char. Nearby birds burst into flames in mid-air, and
dry, combustible materials such as paper instantly ignited
as far away as 6,400 feet from ground zero. The
white light acted as a giant flashbulb, burning the dark
patterns of clothing onto skin (right) and the shadows of
bodies onto walls. Survivors outdoors close to the
blast generally describe a literally blinding light
combined with a sudden and overwhelming wave of
heat. (The effects of
radiation are usually not immediately
apparent.) The blast wave followed
almost instantly for those close-in, often knocking them
from their feet. Those that were indoors were
usually spared the flash burns, but flying glass from
broken windows filled most rooms, and all but the very
strongest structures collapsed. One boy was blown
through the windows of his house and across the street as
the house collapsed behind him. Within minutes 9 out
of 10 people half a mile or less from ground zero were
dead.
People farther from the point of detonation experienced
first the flash and heat, followed seconds later by a
deafening boom and the blast wave. Nearly every
structure within one mile of ground zero was destroyed,
and almost every building within three miles was
damaged. Less than 10 percent of the buildings in
the city survived without any damage, and the blast wave
shattered glass in suburbs twelve miles
away. The most common first
reaction of those that were indoors even miles from ground
zero was that their building had just suffered a direct
hit by a bomb. Small ad hoc rescue parties soon
began to operate, but roughly half of the city's
population was dead or injured. In those areas most
seriously affected virtually no one escaped serious
injury. The numerous small fires that erupted
simultaneously all around the city soon merged into one
large firestorm, creating extremely strong winds that blew
towards the center of the fire. The firestorm
eventually engulfed 4.4 square miles of the city, killing
anyone who had not escaped in the first minutes after the
attack. One postwar study of the victims of
Hiroshima found that less than 4.5 percent of survivors
suffered leg fractures. Such injuries were not
uncommon; it was just that most who could not walk were
engulfed by the firestorm.
Even after the flames had subsided, relief from the
outside was slow in coming. For hours after the
attack the Japanese government did not even know for sure
what had happened. Radio and telegraph
communications with Hiroshima had suddenly ended at 8:16
a.m., and vague reports of some sort of large explosion
had begun to filter in, but the Japanese high command knew
that no large-scale air raid had taken place over the city
and that there were no large stores of explosives
there. Eventually a Japanese staff officer was
dispatched by plane to survey the city from overhead, and
while he was still nearly 100 miles away from the city he
began to report on a huge cloud of smoke that hung over
it. The first confirmation of exactly what had
happened came only sixteen hours later with the
announcement of the bombing by the
United States. Relief workers from outside the city
eventually began to arrive and the situation stabilized
somewhat. Power in undamaged areas of the city was
even restored on August 7th, with limited rail service
resuming the following day. Several days after the
blast, however, medical staff began to recognize the first
symptoms of radiation sickness among the
survivors. Soon the death rate actually began to
climb again as patients who had appeared to be recovering
began suffering from this strange new
illness. Deaths from radiation sickness did not
peak until three to four weeks after the attacks and did
not taper off until seven to eight weeks after the
attack. Long-range health dangers associated with
radiation exposure, such as an increased danger of cancer,
would linger for the rest of the victims' lives, as would
the psychological effects of the attack.
No one will ever know for certain how many died as a
result of the attack on Hiroshima. Some 70,000
people probably died as a result of initial blast, heat,
and radiation effects. This included about twenty
American airmen being held as prisoners in the city.
By the end of 1945, because of the lingering effects of
radioactive fallout and other after
effects, the Hiroshima death toll was probably over
100,000. The five-year death total may have reached
or even exceeded 200,000, as cancer and other long-term
effects took hold.
At 11:00 a.m., August 6 (Washington D.C. time), radio
stations began playing a prepared statement from
President Truman informing the American
public that the United States had dropped an entirely new
type of bomb on the Japanese city of Hiroshima --
an "atomic bomb." Truman warned that if
Japan still refused to surrender unconditionally, as
demanded by the Potsdam Declaration of
July 26, the United States would attack additional targets
with equally devastating results. Two days later, on
August 8, the Soviet Union declared war on Japan and
attacked Japanese forces in Manchuria, ending American
hopes that the war would end before Russian entry into the
Pacific
theater. By August 9th, American aircraft were
showering leaflets all over Japan informing its people
that "We are in possession of the most destructive
explosive ever devised by man. A single one of our
newly developed atomic bombs is actually the equivalent in
explosive power to what 2,000 of our giant B-29s can carry
on a single mission. This awful fact is one for you
to ponder and we solemnly assure you it is grimly
accurate. We have just begun to use this weapon
against your homeland. If you still have any doubt,
make inquiry as to what happened to Hiroshima when just
one atomic bomb fell on that city." Meanwhile,
Tibbets's bomber group was simply waiting for the weather
to clear in order to drop its next bomb, the
plutonium implosion weapon nicknamed
"Fat Man" (left) that was destined for the city
of Nagasaki.
-
The War Enters Its Final Phase, 1945
-
Debate Over How to Use the Bomb, Late Spring
1945
-
The Trinity Test, July 16, 1945
-
Safety and the Trinity Test, July 1945
-
Evaluations of Trinity, July 1945
-
Potsdam and the Final Decision to Bomb, July
1945
-
The Atomic Bombing of Hiroshima, August 6,
1945
-
The Atomic Bombing of Nagasaki, August 9,
1945
-
Japan Surrenders, August 10-15, 1945
-
The Manhattan Project and the Second World War,
1939-1945
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Sources and notes for this page.
Portions of the text for this page were adapted from,
and portions were taken directly from the
Office of History and Heritage Resources
publication:
F. G. Gosling,
The Manhattan Project: Making the Atomic Bomb
(DOE/MA-0001; Washington: History Division, Department
of Energy, January 1999), 51-53. Also used was the report on "The
Atomic Bombings of Hiroshima and
Nagasaki" in the official
Manhattan District History, produced by the War
Department in 1947 at the direction of
Leslie Groves, especially pages 1-19;
the "Atomic Bombings" document is available in
the University Publications of America microfilm
collection,
Manhattan Project: Official History and Documents
(Washington: 1977), reel #1/12; the report itself is a
government document. Tibbets's description is from
Paul W. Tibbets, "How to Drop an Atom Bomb,"
Saturday Evening Post 218 (June 8, 1946),
136. The estimate of Little Boy's yield is from
United States Nuclear Tests, July 1945
through September 1992 (DOE/NV-209-REV 15; Las Vegas,
NV: Nevada Operations Office, Department of Energy,
December 2000), vii. Summaries of Hiroshima and Nagasaki
casualty rates and damage estimates appear in Leslie R.
Groves, Now It Can Be Told (New York: Harper
& Row, 1962), 319, 329-330, 346, and Vincent C.
Jones, Manhattan: The Army and the Atomic Bomb,
United States Army in World War II (Washington: Center
of Military History, United States Army, 1988),
545-548. A translation of the leaflets dropped on
Japan in between Hiroshima and Nagasaki can be found in
Dennis Merrill, ed.,
Documentary History of the Truman Volume 1,
The Decision to Drop the Atomic Bomb on Japan
(Bethesda, MD: University Publications of America,
1995), 194-195. The photograph of the mushroom
cloud is courtesy the
United States Air Force (USAF)
(via the
National Archives
(NARA)). The photographs of Little Boy and Fat Man
are courtesy the U.S. Army Corps of Engineers (via
NARA). The photograph of the Enola Gay landing at
Tinian Island is courtesy the USAF. The photograph
of the woman with burns on her back is courtesy the U.S.
Army Corps of Engineers (via NARA). The
photographs of the mushroom cloud taken from the ground
and of the debris (including the Hiroshima Peace
Memorial (Genbaku
"A-bomb" Dome) are courtesy the
Federation of American Scientists. The photographs of the hospital and of the lone
soldier walking through an almost-completely leveled
portion of the city are courtesy the Department of the
Navy (via NARA); the former was taken by Wayne
Miller.
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