Before Germany Surrendered:
Even before the surrender of Nazi Germany on the 8th May 1945, plans
were already underway for the largest operation of the Pacific War,
'Operation Downfall', the invasion of Japan; the operation had two parts
'Olympic' and 'Coronet'; 'Olympic' set to begin in October 1945, involved
a series of landings by the U.S. Sixth Army intended to capture the
southern third of the southernmost main Japanese island, Kyushu.
Operation Olympic was to be followed in March 1946 by Operation Coronet,
the capture of the Kanto Plain, near Tokyo on the Japanese island of
Honshu by the U.S. First, Eighth and Tenth Armies; the target date was
chosen to allow for Olympic to complete its objectives, troops to be
redeployed from Europe and the Japanese winter to pass.
Unfortunately, Japan's geography made this invasion plan obvious to
the Japanese as well; they were able to predict the Allied invasion
plans accurately and thus adjust their defensive plan, 'Operation Ketsugo',
accordingly; the Japanese planned an all out defense of Kyushu, with
little left in reserve for any subsequent defense operations.
Four veteran divisions were withdrawn from the Kwantung Army in Manchuria
in March 1945 to strengthen the forces in Japan and 45 new divisions
were activated between February and May 1945; most were immobile formations
for coastal defence, but 16 were high quality mobile divisions; in all,
there were 2.3 million Japanese Army troops prepared to defend the Japanese
home islands, another 4 million Army and Navy employees and a civilian
militia of 28 million men and women.
Casualty predictions varied widely, but were extremely high; the Vice
Chief of the Imperial Japanese Navy General Staff, Vice Admiral Takijiro
Onishi, predicted up to 20 million Japanese deaths; the Americans were
alarmed by the Japanese build up, which was accurately tracked through
The USA Concern Over Estimated Casualties:
The USA Secretary of War Henry Lewis Stimson was sufficiently concerned
about high American estimates of probable casualties to commission his
own study by Quincy Wright and William Shockley; Wright and Shockley
spoke with Colonels James McCormack and Dean Rusk and examined casualty
forecasts by Michael DeBakey and Gilbert Beebe; Wright and Shockley
estimated the invading Allies would suffer between 1.7 and 4 million
casualties in such a scenario, of whom between 400,000 and 800,000 would
be dead, whilst Japanese casualties would have been around 5 to 10 million.
The Chief of Staff of the US Army and the General of the Army George
C. Marshall began contemplating the use of a weapon which was "readily
available and which assuredly can decrease the cost in American lives";
poison gas; quantities of phosgene, mustard gas, tear gas and cyanogen
chloride were moved to Luzon from stockpiles in Australia and New Guinea
in preparation for Operation Olympic and the General of the Army Douglas
MacArthur ensured that Chemical Warfare Service units were trained in
Whilst the USA had developed plans for an air campaign against Japan
prior to the Pacific War, the capture of Allied bases in the western
Pacific in the first weeks of the conflict meant that this offensive
did not begin until mid 1944 when the long ranged Boeing B-29 Superfortress
became ready for use in combat.
Operation 'Matterhorn' involved India based B-29s staging through bases
around Chengtu in China to make a series of raids on strategic targets
in Japan between June 1944 and January 1945; this effort proved unsuccessful
due to logistical difficulties with the remote location, technical problems
with the new and advanced aircraft, unfavourable weather conditions
and ultimately enemy action.
USAAF Brigadier General Haywood S. Hansell determined that Guam, Tinian
and Saipan in the Mariana Islands would better serve as B-29 bases,
but they were in Japanese hands; strategies were shifted to accommodate
the air war and the islands were captured between June and August 1944;
air bases were developed and B-29 operations commenced from the Marianas
in November 1944, greatly expanding the scope of the strategic bombing
campaign against Japan.
These attacks initially targeted key industrial facilities, but from
March 1945 they were frequently directed against urban areas; the capture
of Okinawa in June 1945 provided airfields even closer to the Japanese
mainland, allowing the bombing campaign to be escalated further; over
the next six months, the XXI Bomber Command fire bombed 67 Japanese
cities; the 9 to 10 March Bombing of Tokyo alone caused 80,000 to 100,000
casualties and destroyed around 16 square miles (41 km2) of the city
with 267,000 buildings, the deadliest of the war.
Aircraft flying from Allied aircraft carriers and the Ryukyu Islands
also regularly struck targets in Japan during 1945 in preparation for
Operation Downfall; the Japanese military was unable to stop the Allied
attacks and the country's civil defense preparations proved inadequate;
from April 1945, the Japanese Army and Naval Air Forces stopped attempting
to intercept the air raids in order to preserve fighter aircraft to
counter the expected invasion.
By mid 1945 the Japanese also only occasionally scrambled aircraft to
intercept individual B-29s conducting reconnaissance sorties over the
country in order to conserve supplies of fuel; by July 1945, the Japanese
had stockpiled 1,156,000 US barrels of avgas for the invasion of Japan.
The Manhattan Project:
Working in collaboration with the UK and Canada, with their respective
projects Tube Alloys and Chalk River Laboratories, the Manhattan Project,
under the direction of Major General Leslie Groves, of the U.S. Army
Corps of Engineers, designed and built the first atomic bombs; preliminary
research began in 1939, originally in fear that the Nazi atomic bomb
project would develop atomic weapons first.
In May 1945, the defeat of Germany caused the focus to turn to use against
Japan; two types of bombs were eventually devised by scientists and
technicians at Los Alamos under American physicist Robert Oppenheimer,
a 'Little Boy' type and a 'Fat Man' type.
The USA Target Committee originally nominated four targets; Kokura,
the site of one of Japan's largest munitions plants; Hiroshima, an embarkation
port and industrial center that was the site of a major military headquarters;
Niigata, a port with industrial facilities including steel and aluminium
plants and an oil refinery; and Kyoto, a major industrial center.
The target selection was subject to the following criteria:
The target was larger than 3 miles (4.8 km) in diameter and was an important
target in a large urban area.
The blast would create effective damage.
The target was unlikely to be attacked by August 1945, "Any small
and strictly military objective should be located in a much larger area
subject to blast damage in order to avoid undue risks of the weapon
being lost due to bad placing of the bomb."
These cities were largely untouched during the nightly bombing raids
and the Army Air Force agreed to leave them off the target list so accurate
assessment of the weapon could be made; Hiroshima was described as "an
important army depot and port of embarkation in the middle of an urban
industrial area. It is a good radar target and it is such a size that
a large part of the city could be extensively damaged. There are adjacent
hills which are likely to produce a focusing effect which would considerably
increase the blast damage. Due to rivers it is not a good incendiary
The USA had previously dropped leaflets warning civilians of air raids
on 35 Japanese cities, including Hiroshima and Nagasaki, but not of
the atomic bomb as such; the goal of the weapon was to convince Japan
to surrender unconditionally in accordance with the terms of the Potsdam
The Target Committee stated that it was agreed that psychological factors
in the target selection were of great importance; two aspects of this
are, to obtain the greatest psychological effect against Japan and making
the initial use sufficiently spectacular for the importance of the weapon
to be internationally recognised when publicity on it is released.
Kyoto had the advantage of being an important center for military industry,
as well an intellectual center and hence better able to appreciate the
significance of the weapon; the Emperor's palace in Tokyo has a greater
fame than any other target but is of least strategic value.
Edwin O. Reischauer a Japananese expert for the U.S. Army Intelligence
Service, was incorrectly said to have prevented the bombing of Kyoto;
in his autobiography, Reischauer specifically refuted this claim by
stating that the only person deserving credit for saving Kyoto from
destruction was Henry L. Stimson, the Secretary of War at the time,
who had known and admired Kyoto ever since his honeymoon there several
decades earlier and on the 25th July, Nagasaki was put on the target
list in place of Kyoto.
Germany Surrenders - Japan Fights On Defiantly:
The war in Europe ended when Nazi Germany signed its instrument of surrender
on the 8th May 1945, but the Pacific War continued; therefore, on the
26 July, the USA, together with the UK and the Republic of China issued
the Potsdam Declaration outlining terms of surrender for Japan; it was
presented as an ultimatum and stated that without a surrender, the Allies
would attack Japan, resulting in "the inevitable and complete destruction
of the Japanese armed forces and just as inevitably the utter devastation
of the Japanese homeland"; however, the atomic bomb was not mentioned
in the communiqué.
The Japanese government ignored this ultimatum and on the 28th July
Japanese papers reported that the declaration had been rejected by the
Japanese government; that afternoon, Prime Minister Kantaro Suzuki declared
at a press conference that the Potsdam Declaration was no more than
a rehash of the Cairo Declaration and that the government intended to
ignore it (mokusatsu, "kill by silence"); the statement was
taken by both Japanese and foreign papers as a clear rejection of the
declaration; Emperor Hirohito, who was waiting for a Soviet reply to
non committal Japanese peace feelers, made no move to change the government
Under the 1943 Quebec Agreement with the UK, the USA had agreed that
nuclear weapons would not be used against another country without mutual
consent; therefore in June 1945 the head of the British Joint Staff
Mission, Field Marshal Sir Henry Maitland Wilson, agreed that the use
of nuclear weapons against Japan would be officially recorded as a decision
of the Combined Policy Committee.
At Potsdam, Truman agreed to a request from the Prime Minister of the
UK, Winston Churchill, that Britain be represented when the atomic bomb
was dropped; William Penney and Group Captain Leonard Cheshire were
sent to Tinian, but found that Major General Curtis LeMay would not
let them accompany the mission; all they could do was send a strongly
worded signal back to Wilson.
The Hiroshima Bombing:
Hiroshima was the primary target of the first nuclear bombing mission
on the 6th August, with Kokura and Nagasaki as alternative targets;
the 393d Bombardment Squadron B-29 'Enola Gay', piloted by Tibbets,
was launched from North Field airbase on Tinian, about six hours flight
time from Japan.
The 'Enola Gay', named after Tibbets' mother, was accompanied by two
other B-29s, 'the Great Artiste', commanded by Major Charles W. Sweeney,
carried instrumentation and a then nameless aircraft later called 'Necessary
Evil', commanded by Captain George Marquardt, served as the photography
After leaving Tinian the aircraft made their way separately to Iwo Jima
where they rendezvoused at 8,010 feet (2,440 meters) and set course
for Japan; the aircraft arrived over the target in clear visibility
at 32,333 feet (9,855 meters); Parsons, who was in command of the mission,
armed the bomb during the flight to minimize the risks during takeoff;
his assistant, Second Lieutenant Morris Jeppson, removed the safety
devices 30 minutes before reaching the target area.
About an hour before the bombing, Japanese early warning radar detected
the approach of some American aircraft headed for the southern part
of Japan; an alert was given and radio broadcasting stopped in many
cities, among them Hiroshima; at nearly 08:00, 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.