Katana VentraIP

Air raids on Japan

During World War II, Allied forces conducted air raids on Japan from 1942 to 1945, causing extensive destruction to the country's cities and killing between 241,000 and 900,000 people. During the first years of the Pacific War these attacks were limited to the Doolittle Raid in April 1942 and small-scale raids on military positions in the Kuril Islands from mid-1943. Strategic bombing raids began in June 1944 and continued until the end of the war in August 1945. Allied naval and land-based tactical air units also attacked Japan during 1945.

The United States Army Air Forces campaign against Japan began in earnest in mid-1944 and intensified during the war's last months. While plans for attacks on Japan had been prepared prior to the Pacific War, these could not begin until the long-range Boeing B-29 Superfortress bomber was ready for combat. From June 1944 until January 1945, B-29s stationed in India staged through bases in China to make a series of nine raids on targets in western Japan, but this effort proved ineffective. The strategic bombing campaign was greatly expanded from November 1944 when bases in the Mariana Islands became available as a result of the Mariana Islands Campaign. Initial attempts to target industrial facilities using high-altitude daylight "precision" bombing were largely ineffective. From February 1945, the bombers switched to low-altitude night firebombing against urban areas as much of the manufacturing process was carried out in small workshops and private homes: this approach resulted in large-scale urban damage and high civilian casualties. Aircraft flying from Allied aircraft carriers and the Ryukyu Islands also frequently struck targets in Japan during 1945 in preparation for the planned invasion of Japan scheduled for October 1945. During early August 1945, the cities of Hiroshima and Nagasaki were struck and mostly destroyed by atomic bombs.


Japan's military and civil defenses were unable to stop the Allied attacks. The number of fighter aircraft and anti-aircraft guns assigned to defensive duties in the home islands was inadequate, and most of these aircraft and guns had difficulty reaching the high altitudes at which B-29s often operated. Fuel shortages, inadequate pilot training, and a lack of coordination between units also constrained the effectiveness of the fighter force. Despite the vulnerability of Japanese cities to incendiary bombs, the firefighting services lacked training and equipment, and few air raid shelters were constructed for civilians. As a result, the B-29s were able to inflict severe damage on urban areas while suffering few losses.


The Allied bombing campaign was one of the main factors which influenced the Japanese government's decision to surrender in mid-August 1945. However, there has been a long-running debate over the morality of the attacks on Japanese cities, and the use of atomic weapons is particularly controversial. The most commonly cited estimate of Japanese casualties from the raids is 333,000 killed and 473,000 wounded. Other estimates of total fatalities range from 241,000 to 900,000. In addition to the loss of mostly civilian life, the raids contributed to a large decline in industrial production.

Background[edit]

United States plans[edit]

The United States Army Air Corps (which was subsumed by the United States Army Air Forces (USAAF) in February 1942)[7] began developing contingency plans for an air campaign against Japan during 1940. During that year the naval attaché to the Embassy of the United States in Tokyo reported that Japan's civil defenses were weak, and proposals were made for American aircrew to volunteer for service with Chinese forces in the Second Sino-Japanese War.[8] The first American Volunteer Group (the "Flying Tigers") began operations as part of the Republic of China Air Force (ROCAF) in late 1941 using P-40 Warhawk fighter aircraft. A second American Volunteer Group was also formed in late 1941 to attack Japan from bases in China using Hudson and A-20 Havoc medium bombers. The attack on Pearl Harbor on 7 December 1941 led to open hostilities between the US and Japan and ended the need for covert operations, however, and this unit did not become active. The small number of Second Air Volunteer Group personnel who were dispatched from the United States in November 1941 were diverted to Australia upon the outbreak of war.[9][10]


Japanese successes during the opening months of the Pacific War nullified pre-war US plans for attacks against the Japanese homeland and a series of attempts to start a small-scale campaign from bases in China were unsuccessful. Before the outbreak of war, the USAAF had planned to bomb Japan from Wake Island, Guam, the Philippines and coastal areas in China.[9] However, these areas were rapidly captured by Japanese forces, and the USAAF heavy bomber force in the Philippines was largely destroyed when Clark Air Base was attacked on 8 December 1941.[11] The USAAF subsequently attempted to send thirteen heavy bombers to China in March and April 1942 to attack the Japanese home islands. These aircraft reached India, but remained there as the Japanese conquest of Burma caused logistics problems and Chinese Nationalist leader Chiang Kai-shek was reluctant to allow them to operate from territory under his control. A further 13 B-24 Liberator heavy bombers were dispatched from the United States to operate from China in May 1942 as the HALPRO force, but were re-tasked to support Allied operations in the Mediterranean.[12] In July 1942, the commander of the American Volunteer Group, Colonel Claire Lee Chennault, sought a force of 100 P-47 Thunderbolt fighters and 30 B-25 Mitchell medium bombers, which he believed would be sufficient to "destroy" the Japanese aircraft industry. Three months later Chennault told United States President Franklin D. Roosevelt that a force of 105 modern fighters and 40 bombers (including twelve heavy bombers) would be able to "accomplish the downfall of Japan" within six to twelve months. The USAAF's headquarters did not regard these claims as credible, and Chennault's requests for reinforcements were not granted.[12]

Early raids[edit]

Chinese raid[edit]

The Republic of China Air Force (ROCAF) conducted a single attack on the Japanese home islands during the Second Sino-Japanese War. On 19 May 1938 two ROCAF Martin B-10 bombers dropped propaganda leaflets on Nagasaki, Fukuoka, Kurume, Saga, and other locations on Kyushu. These leaflets did not have any effect on Japanese civilians, but demonstrated that China could potentially conduct small scale air attacks on the area. The Japanese military later incorrectly concluded that the ROCAF had aircraft capable of mounting attacks at a range of 1,300 miles (2,100 km) from their bases, and took precautions against potential raids on western Japan when Chinese forces launched an offensive during 1939.[23]

Firebombing attacks[edit]

LeMay changes tactics[edit]

USAAF planners began assessing the feasibility of a firebombing campaign against Japanese cities in 1943. Japan's main industrial facilities were vulnerable to such attacks as they were concentrated in several large cities and a high proportion of production took place in homes and small factories in urban areas. The planners estimated that incendiary bomb attacks on Japan's six largest cities could cause physical damage to almost 40 percent of industrial facilities and result in the loss of 7.6 million man-months of labor. It was also estimated that these attacks would kill over 500,000 people, render about 7.75 million homeless and force almost 3.5 million to be evacuated.[92][93] In 1943 the USAAF tested the effectiveness of incendiary bombs on Japanese-style buildings at Eglin Field and the "Japanese Village" at Dugway Proving Ground.[94] The American military also attempted to develop "bat bombs", using incendiary bombs attached to bats dropped by aircraft to attack Japanese cities, but this project was abandoned in 1944.[95] During early 1945 the USAAF conducted raids against cities in Formosa to trial tactics which could be later used against Japanese urban areas.[96]


Napalm, used by the Americans for flamethrowers and incendiary bombs, was increased in production from 500,000 lb (230,000 kg) in 1943 to 8 million lb (3.6 kt) in 1944. Much of the napalm went from nine US factories to bomb-assembly plants making the M-69 incendiary and packing 38 of them into the E-46 cluster bomb; these were shipped across the Pacific and stored for future use.[97] Arnold and the Air Staff wanted to wait to use the incendiaries until a large-scale program of firebombing could be mounted, to overwhelm the Japanese city defenses.[98]


In light of the poor results of the precision bombing campaign and the success of the 25 February raid on Tokyo, and considering that many tons of incendiaries were now available to him, LeMay decided to begin firebombing attacks on Japan's main cities during early March 1945.[98][99] This was in line with Arnold's targeting directive for XXI Bomber Command, which specified that urban areas were to be accorded the second-highest priority for attacks after aircraft factories. The directive also stated that firebombing raids should be conducted once M-69 bombs had been tested in combat and the number of B-29s available was sufficient to launch an intensive campaign.[100] LeMay did not seek Arnold's specific approval before launching his firebombing campaign, however, to protect the USAAF commander from criticism if the attacks were unsuccessful. The Twentieth Air Force's Chief of Staff, Brigadier General Lauris Norstad, was aware of the change in tactics though and provided support.[101] The decision to use firebombing tactics represented a move away from the USAAF's previous focus on precision bombing, and was believed by senior officials in the military and US Government to be justified by the need to rapidly bring the war to an end.[102]


To maximize the effectiveness of the firebombing attacks, LeMay ordered the B-29s to fly at the low altitude of 5,000 feet (1,500 m) and bomb by night; this represented a significant change from the Command's standard tactics, which focused on high-altitude daylight bombing. As Japan's night fighter force was weak and the anti-aircraft batteries were less effective at night, LeMay also had most of the B-29s' defensive guns removed; by reducing the weight of the aircraft in this way they were able to carry more bombs.[89] These changes were not popular with XXI Bomber Command's aircrew, as they believed that it was safer to fly heavily armed aircraft at high altitude.[103]

Japanese military response[edit]

Air defenses[edit]

Japan's air defenses were unable to stop the Allied air attacks.[208] Owing to the short range of the country's land-based radar, and Allied attacks on IJN picket ships, the defenders typically had only about an hour to respond to incoming B-29s once they had been detected. Japanese signals intelligence units could provide longer warning times of incoming raids by eavesdropping on the bombers' radio communications, but were unable to predict the target of the attack. As a result, fighter units did not have enough time to scramble and reach the bombers' cruising altitude before they arrived over their target, and most raids were intercepted by only small numbers of aircraft. Moreover, the American bombers were capable of flying faster at high altitude than many Japanese fighters.[209] Even when the fighters managed to close within gun range, the well-built B-29s were often able to sustain large amounts of damage. Due to the difficulty of intercepting and downing B-29s, the Japanese fighter pilots increasingly perceived their efforts as being futile.[142] From August 1944 Japanese aircraft occasionally conducted suicide ramming attacks on B-29s, and several specialized kamikaze fighter units were established in October; by the end of the war, ramming tactics had destroyed nine B-29s and damaged another 13 for the loss of 21 fighters.[210]

Strategic bombing during World War II

Grave of the Fireflies

Japanairraids.org