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National Archives. Via Frank (1999)
was one of the most
controversial aspects of the Second World War, from both a military and
moral perspective. Beginning with the Italian Giulio Douhet in 1921 (Command of the Air), the possibility that a nation could be defeated
solely by air attacks on its economic
infrastructure was studied
extensively by air power advocates. The U.S.
Tactical School closely studied Douhet, and Brigadier General Billy
Mitchell embraced the concept of strategic bombing after touring the
Far East in 1923-1924 and concluding that Japanese cities were "highly inflammable." However, the views of the "bomber
cult" that grew up around Mitchell clashed with those of the Army
General Staff, which believed that the proper role of air power was to
support surface forces through reconnaissance
and direct ground support. Mitchell became so vituperative in his
attacks on the views of the General Staff that he was court-martialed
for insubordination in October 1925. A month later, the Morrow Board
concluded that establishment of an independent air force would be
premature given the contemporary limitations on bomber range.
Mitchell then appealed directly to the public, arguing in his book Skyways
(1930) against the Clausewitzian doctrine that the proper objective of
war was the destruction of the enemy army. Mitchell argued that air
power could bypass the enemy army and strike directly at the enemy's
"vital centers," destroying his capacity to make war and forcing him to
capitulate. However, many civilian
leaders had serious moral qualms
about the collateral damage to noncombatants that would be inevitable
in a strategic bombing campaign. Indiscriminate attacks on civilians were generally considered a
violation of the customs of war, though the legal status of attacks on
cities containing military facilities or war industries was
unclear. The Hague
banned bombs and projectiles dropped
from balloons, but were never
updated to include attacks from heavier-than-air aircraft.
Mitchell was unable to turn public opinion before
his death in 1936. However, the concept of an independent air force
organized for strategic bombing held considerable appeal to airmen. The
activation of of General Headquarters Air Force on 1 March 1935 and the
first test flights of the B-17 Flying
Fortress later that summer were the first steps in what became a steady march. The creation of the Axis in 1937 led to Roosevelt's call for a massive buildup in air power on 12 January 1939. Both airmen and Winston Churchill viewed the Munich pact of 29 September 1938 as blackmail driven by the threat of German air power.
There remained the question of the appropriate targets for strategic bombing. Advocates
of precision bombing argued that bombers should target key industries
and infrastructure whose destruction would cripple the enemy's
warmaking capacity. In contrast to this surgical approach, advocates
bombing" argued that area bombing of population centers would rapidly
destroy civilian morale and create irresistible political pressure for
a capitulation. When the ACTS published Employment of Combined Air Force in
1926, the enemy population was included with critical industries and
the enemy air force as one of the principle objectives of a strategic
Just how the people of a totalitarian state at war would exert such
pressure remained unexplained. However, those Air Force leader most
attuned to public opinion, such as Hap Arnold,
seized on precision bombing as a way to defuse the moral objections:
Precision bombing held out the promise of destroying a nation's
warmaking capacity without killing large numbers of women
and children. However, even the advocates of precision bombing tended to
view it in terms of its adverse effect on civilian morale.
The debates over air power in the United States
were paralleled by similar debates in all the other major powers.
However, airmen in Britain, France, Germany, and Italy
were able to establish independent air forces, while the air forces of the United
States remained nominally under Army and Navy control. The Japanese Army and
Navy retained tight control over their respective air arms, though both
services developed long-range bombers.
The "bomber cult" of the British Royal Air Force was as powerful as
that of the U.S. Army Air Force, but the airmen of the other powers
were less successful in resisting pressure to devote most of their
resources to ground support. Some idea of the dogmatism of Britain's "bomber cult" can be gleaned from Cunningham's
recollection that "Bomber Harris complained what a nuisance this
Overlord operation was and how it interfered with the right way to
defeat Germany, i.e. by bombing" (Roberts 2011).
When war broke out, the first experiments in
strategic bombing were carried out by the Axis against weaker powers
that had no capacity to retaliate. Japan
engaged in indiscriminate bombing in China
(particularly of Chungking),
and Germany carried out bombings
of Warsaw in Poland and Rotterdam in the Netherlands that were highly
questionable from a military or economic warfare perspective. Initially, the Allies avoided
strategic bombing. There is a famous anecdote that Chamberlain, Churchill's
predecessor as Prime Minister of the United Kingdom,
refused to give his air commanders permission to bomb the German arms
factories in the Ruhr on the grounds that they were private property.
Long-range bombing was limited to obvious military targets, such as the
naval base at Wilhemshaven. This
changed during the Battle of Britain.
A German bomber flight became lost and jettisoned its bombs, as it
turned out, over the East End of London. Britain retaliated with a
bombing raid against Berlin that came nowhere near the city center
aerial navigation being very primitive) but infuriated the Nazi
leadership. This led to the
"Blitz" against British cities, in which
tens of thousands of civilians were killed and many more left homeless.
At this point, moral qualms were largely abandoned in favor of an "if
that's how they want to play the game ..." attitude. Allied leaders
such as Sir Arthur Harris of Bomber Command voiced the opinion
that the Axis,
sown the wind, were entitled to reap the whirlwind. Roosevelt also
voiced this sentiment, stating that he wanted the Axis bombed "heavily
and relentlessly ... they have asked for it and they are going to get
it" (Wolk 2010).
The military effectiveness of strategic bombing in Europe is
controversial as its morality. German production actually increased
during the peak of the strategic bombing campaign, though most of the
increased production was in occupied countries out of range of
Allied bombers. The morale of the
German people never cracked under
bombardment, contrary to the expectations of Allied air commanders.
Bomber casualties were heavy.
This was particularly true among American
bomber crews, since the Americans grossly overestimated the
survivability of their strategic bombers on daylight raids.
Ironically, the decision to risk heavy casualties in
bombing was based on a belief in precision bombing, which specifically
targeted factories and communications rather than civilians. British
bombers were employed for area bombing at night, but also began to
suffer serious casualties as German night fighter defenses
Once long-range fighters began escorting American bombers, casualties soared among the defending German fighter pilots. This was a major contributing factor to the collapse of the Luftwaffe in the West and the success of the Anglo-American invasion of France. When the Allies finally focused their strategic bombing on synthetic fuel plants and other petroleum facilities, early in 1945, the Germans quickly ran out of fuel. This was an important contributing factor to the collapse of the Wehrmacht. However, the Russian capture of the oilfields in Romania and Austria were probably as important as the strategic bombing campaign.
The most sustained and destructive strategic bombing campaign prior to 1942 was carried out by the Japanese in China. Beginning in 1937, more than 50 cities were attacked, and some of the raids on Chungking in 1941 caused as many as 4000 deaths. A coordinated campaign against Chungking, Chengtu, Sian, Lanchow and other cities, Operation 101, began on 31 July 1940 and continued through the autumn. One raid on 20 August 1940 involved 170 Japanese aircraft dropping incendiaries. Some 2000 tons of bombs were dropped on Chungking alone during the campaign. However, the Japanese never developed a true strategic bomber. Navy bombers such as the G3M "Nell", with its very long range, proved vulnerable to fighter defenses but bombed with impunity wherever they could be escorted by the A5M "Claude" or the A6M "Zero". Heavy bombing attacks on Chungking, Kunming, and other cities wrecked any possibility the Chinese had of building up a sizable arms production industry. U.S. Secretary of State Cordell Hull protested (Wolk 2010):
[The Japanese] have in large number of instances resorted to bombing and machine-gunning of civilians from the air at places near which there were no military establishments or organizations. Furthermore, the use of incendiary bombs has inflicted appalling losses on civilian populations. Japanese air attacks in many instances have been of a nature and apparent plan which can be comprehended only as constituting deliberate attempts to terrorize unarmed populations.
As early as November 1940, Chennault
(then an advisor to the Chinese government) urged the use of the same
tactics against the Japanese to "burn out the industrial heart of the
Empire with firebomb attacks on the teeming bamboo ant heaps of Honshu and Kyushu." However, after war broke out in the Pacific and the American Volunteer Group
began operating in China, Japanese strategic bombing came virtually to
The Americans began the war with the B-17 Flying Fortress, arguably the world's first true strategic bomber. Both the B-17 and its successor, the B-24 Liberator, were used extensively for patrolling and tactical bombing in the Pacific. Neither had the range to reach important strategic targets deep in the Japanese Empire. However, this picture began to change on 15 June 1944, when the first B-29 Superfortress raid reached Kyushu from 20 Air Force bases in China. At first, the Superfortresses carried out daylight precision bombing raids, but these were disappointing. Logistics were nearly unmanageable, requiring seven B-29 flights loaded with gasoline from India to supply each combat sortie. Japanese agents in China gave hours of warning of every raid. High-altitude flying conditions over Japan were miserable due to the proximity of the jet stream. In addition, Japan is frequently cloud-covered, and the Allies started with meager intelligence on most targets.
From the period between June 1944 and April 1945, 20 Bomber Command in India and China launched 49 missions, of which
just nine were directed against the Japanese home islands. The first
such mission left India on 13 June 1944 with 92 B-29s, of which 12 were
forced to abort and one was lost in the flight to Chengtu.
68 of these were able to take off the next day for Kyushu, but one
crashed on takeoff and only 47 actually reached the Imperial Iron and Steel Works at Yawata. Night conditions and poor weather meant most of the aircraft bombed by radar;
of 221 tons of bombs dropped, just one hit the target. One bomber was
shot down and another six others were lost in accidents. The commander
of 20 Bomber Command, Kenneth Wolfe, was kicked upstairs and, on 29 August 1944, Curtis LeMay
took command in his place. However, the difficulties of attacking Japan
from China were simply too great. The nine missions flown against Japan
cost 125 B-29s, of which 29 were lost to enemy action. The only
significant damage was to the small Omura naval air arsenal.
With the capture of the larger Mariana Islands,
the U.S. strategic air forces were able to establish airfields that had
an adequate line of supply and
from which the B-29s could reach most of
Japan. The results of high-altitude daylight precision bombing
continued to disappoint, however. The first raid on the Tokyo area, on 24 November 1944, hit the Musashino
aircraft plant with just 48 out of 240 bombs dropped. Two B-29s and
five Japanese interceptors were lost. Once again, the commander of 21 Bomber Command, "Possum" Hansell,
was relieved by LeMay. LeMay initially had no better success, and,
under intense pressure from Arnold, he switched to night area bombing
incendiaries. By bombing at night,
the B-29s could fly at lower altitude and
with less defensive armament, allowing more incendiaries to be carried
to the targets. The incendiaries themselves were more potent than ever,
containing a combination of napalm
and magnesium. The risk was that
the bombers would be highly vulnerable to light antiaircraft fire, but
LeMay gambled correctly that this would be very weak.
The first raid using the new tactics, against Tokyo on the night of
9-10 March 1945, involved 279 B-29s dropping over 1650 tons of
incendiaries. It was a windy night, and wind gusts of up to 70 miles per
hour (110 km/h) fanned
the flames beyond all possibility of control. Witnesses later claimed
that the fires were hot enough to boil the water in the city's canals.
The death toll
was somewhere between 80,000 and 120,000 persons. This was probably the
most devastating single air raid of the war, exceeding even the nuclear raids.
From then on, the U.S. strategic air forces began systematically
burning the cities of Japan to the ground.
Japanese defenses were pitifully inadequate and civil defense was rudimentary. Tokyo had just 18 concrete air raid shelters with a combined capacity of 5,000 persons. The coastal plains on which most of Japan's cities were built were composed of unstable soil derived from volcanic ash, which hindered excavation. The only shelter for most civilians was bokugo, small holes six to 15 feet (two to five meters) long, three feet (one meter) across, and four to six feet (1.5 to 2 meters) deep, with bamboo roofs covered with a thin layer of dirt. These were dug next to homes or along streets, and proved almost useless. Tokyo authorities had ordered the demolition of some 207,370 homes to produce 31 miles of firebreaks by March 1944, but in many cases the timber from the demolished homes had not yet been removed.
LeMay justified this campaign of mass destruction with the observation that Japanese industry, while concentrated in the largest cities, was fairly dispersed within those cities. Most Japanese factories relied on parts manufactured on what was nearly a cottage basis in small neighborhood workshops. LeMay later stated that
We were going after military targets. No point in slaughtering civilians for the mere sake of slaughter. Of course there is a pretty thin veneer in Japan, but the veneer was there. It was their system of dispersal of industry.... I'll never forget Yokohama. That was what impressed me: drill presses. There they were, like a forest of scorched trees and stumps, growing up throughout the residential area. Flimsy construction all gone ... everything burned down, or up, and drill presses standing like skeletons.
Dr. Karl T. Compton made a similar observation to Truman in October
Standing in the ashes of a substantial portion of the burned homes [in Tokyo] are various types of machine tools like lathes, drill presses, etc. Here family groups were manufacturing repetitive parts like nuts, bolts, or coils which were delivered to the manufacturing centers for use in the assembly of military weapons. In the area we examined, approximately one fifth of the homes showed evidence of such activities.
This view seemed to be shared by the chief of staff of General Air Army, Tazoe Noboru (Tillman 2010):
It became apparent in March 1945 that Japan could not win the war when the B-20s wrought extensive damage, especially in the case of small factories scattered throughout the cities.
and by Rear Admiral Toshitane Takata (ibid.):
The fire bomb raids destroyed most of the smaller factories making aircraft parts, thus causing serious losses in production. The many small plants scattered over the cities which were destroyed caused serious loss in other material and general production. Aircraft engine production always lagged behind a safe ratio to airframe production and was frequently numerically inferior for individual types.
Another factor underlying LeMay's departure from the
previous American insistence on precision daylight bombing was the mass
of civilians on Saipian,
suggested to some that there was no meaningful distinction between
Japanese combatants and noncombatants. Arnold and LeMay were also
under pressure from Roosevelt, who was a strong supporter of strategic
bombing and seems never to have expressed any serious qualms about area
bombing of Japanese cities.
Later in the campaign, leaflets
would be dropped a day or two in
advance of a raid, announcing the next target and admonishing civilians
to flee to the countryside. It is unlikely this was motivated primarily
by humanitarians concerns. It was more likely a form of psychological
warfare, demonstrating to Japanese civilians that their government was
powerless to protect them even when raids were announced well in
advance. There is some evidence that this form of psychological warfare
was highly effective.
Total casualties and damage from the strategic bombing campaign are
give in the table below (Frank 1999).
A different form of strategic bombing was aerial offensive mine laying. These missions were
inexpensive and very effective at shutting down Japanese coastal
shipping. Aerial mine laying by Superfortresses began with Operation
Starvation, which laid 900 mines in April 1945. Shimonoseki Strait was
shut down for two weeks and total Japanese imports dropped by half.
Desperate Japanese commanders ordered ships to run the strait anyway,
resulting in heavy shipping losses. By the end of the war, the
Superfortresses had laid 12,000 mines and were responsible for 63% of
all shipping losses suffered by the Japanese during the period of the
mining campaign. The mine campaign is summarized in the table below
|Phase 1: Okinawa
||3-27 to 4-12
|Phase 2: Inland Sea
||5-3 to 5-5
|Phase 3: Northwest Honshu-Kyushu
||5-8 to 5-27
|Phase 4: Northwest Honshu-Kyushu
||6-7 to 7-3
|Phase 5: Total blockade
||7-9 to 8-14
||3-27 to 8-14
Also of strategic importance was the sinking by carrier aircraft on 14-15
July 1945 of eight of the twelve railway ferries that carried traffic
between Hokkaido and Honshu. This immediately halved
deliveries of coal to Honshu.
The ultimate expression of strategic bombing were the nuclear attacks on Hiroshima and Nagasaki. The importance of these raids in forcing the Japanese to surrender has been questioned, but they were likely a major factor (along with the sea blockade and the Russian invasion of Manchuria) in the Emperor's final decision.
The total tonnage of bombs dropped on Japan was 160,800 tons out of a total of 656,400
tons dropped in the Pacific War. By contrast, Germany was hit by
1,360,000 tons of bombs out of 2,700,000 tons of bombs dropped in the
European theater. This tends to confirm the idea that Japanese cities
were particularly vulnerable to fire bombing, and stands in contrast
with a wartime estimate that 1,620,000 tons of bombs would be enough to
knock Japan out of the war.
However, the overall effects of the strategic bombing campaign are disputed. Industrial productivity in most categories was reduced to about half its 1944 peak by July 1945. Aluminum production had come to a near standstill at 9% of its 1944 peak. However, the massive drop in productivity likely owes at least as much to the destruction of the Japanese merchant marine, and the resulting loss of imports of raw materials, as to the destruction of the factories themselves.
Had the war continued past August 1945, the next target for
strategic bombing was to be Japan's rail system. Because of Japan's mountainous terrain, the rail
system was unusually vulnerable to attack, which would have made it
impossible to move vital commodities such as rice. Frank (1999) has argued that this
would have led to widespread famine that would have forced a surrender
without the nuclear attacks, but at the cost of perhaps as many as ten
million deaths by starvation. As it was, disastrous declines in rice
production coupled with blockade meant that the occupation authorities
had to import 800,000 tons of food in 1946.
Peattie et al. (2011)
United States Strategic Bombing Survey (1946; accessed 2011-6-25)
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