On the night of 9/10 March 1945, the United States Army Air Forces (USAAF) conducted a devastating firebombing raid on Tokyo, the Japanese capital city. This attack was code-named Operation Meetinghouse by the USAAF and is known as the Tokyo Great Air Raid (東京大空襲, Tōkyō dai-kūshū) in Japan. Bombs, dropped from 279 Boeing B-29 Superfortress heavy bombers, burned out much of eastern Tokyo. More than 90,000 and possibly over 100,000 Japanese people were killed, mostly civilians, and one million were left homeless. This made the operation the most destructive single air attack, including the atomic bombings of Hiroshima and Nagasaki. The Japanese air and civil defenses proved largely inadequate; 14 American aircraft and 96 airmen were lost.
The attack on Tokyo was an intensification of the air raids on Japan which had begun in June 1944. Prior to this operation, the USAAF had focused on a precision bombing campaign against Japanese industrial facilities. These attacks were generally unsuccessful, which contributed to the decision to shift to firebombing. The operation during the early hours of 10 March was the first major firebombing raid against a Japanese city. The USAAF units employed significantly different tactics from those used in precision raids, including bombing by night with the aircraft flying at low altitudes. The extensive destruction caused by the raid led to these tactics becoming standard for the USAAF's B-29s until the end of the war.
There has been a long-running debate over the morality of the 10 March firebombing of Tokyo. The raid is often cited as a key example in criticism of the Allies' strategic bombing campaigns. Many historians and commentators argue that it was not acceptable for the USAAF to deliberately target civilians; other historians believe that the USAAF had no choice but to change to area bombing tactics given that the precision bombing campaign had failed. It is generally acknowledged that the tactics used against Tokyo and in similar subsequent raids were militarily successful. The attack is commemorated in Japan at two official memorials, several neighborhood memorials, and a privately owned museum.
Background
Pre-war USAAF doctrine emphasized the precision bombing of key industrial facilities over area bombing of cities. Early American strategic bombing attacks on Germany used precision tactics, with the bomber crews seeking to visually identify their targets. This proved difficult to achieve in practice. During the last 20 months of the war in Europe, non-visual attacks accounted for about half of the American strategic bombing campaign against Germany. These included major area bombing raids on Berlin and Dresden, as well as attacks on several towns and cities conducted as part of Operation Clarion. The American attacks on Germany mainly used high-explosive bombs, with incendiary bombs accounting for only 14 percent of those dropped by the Eighth Air Force. The British Bomber Command focused on destroying German cities from early 1942 until the end of the war, and incendiaries represented 21 percent of the tonnage of bombs its aircraft dropped. Area bombing of German cities by Allied forces resulted in the deaths of hundreds of thousands of civilians and massive firestorms in cities such as Hamburg and Dresden.
Japanese forces conducted area bombing attacks on Chinese cities throughout the war. Few attempts were made to target industrial facilities, with the goal of the campaign being to terrorize civilians and cut the Chinese forces off from their sources of supplies. Chongqing, China's provisional capital, was frequently attacked by aircraft using incendiary and high explosive bombs. These raids destroyed most of the city.
The American Doolittle Raid on 18 April 1942 was the first air attack on Tokyo, but inflicted little damage on the city. In June 1944, the USAAF's XX Bomber Command began a campaign against Japan using B-29 Superfortress bombers flying from airfields in China. Tokyo was beyond the range of Superfortresses operating from China, and was not attacked. This changed in October 1944, when the B-29s of the XXI Bomber Command began moving into airfields in the Mariana Islands. These islands were close enough to Japan for the B-29s to conduct a sustained bombing campaign against Tokyo and most other Japanese cities. The first Superfortress flight over Tokyo took place on 1 November, when a reconnaissance aircraft photographed industrial facilities and urban areas in the western districts of the city. The remainder of Tokyo was photographed in subsequent reconnaissance flights, and these images were used to plan the 10 March raid and other attacks on urban areas.
The overall plan for the strategic bombing campaign against Japan specified that it would commence with precision bombing raids against key industrial facilities, and later include firebombing attacks on cities. The first target directive issued to the XXI Bomber Command by its parent unit, the Twentieth Air Force, on 11 November, 1944 specified that the main target was Japanese aircraft and aviation engine factories. These targets were to be attacked by precision bombing. Japanese cities were specified as the secondary target, with area bombing being authorized for use against them. The directive also indicated that firebombing raids were likely to be ordered against cities to test the effectiveness of this tactic. The Twentieth Air Force had an unusual command structure, as it was personally headed by General Henry H. Arnold, the commanding officer of the USAAF.
B-29 raids on Tokyo commenced on 24 November. The first raid targeted an aircraft engine factory on the city's outskirts, and caused little damage. XXI Bomber Command's subsequent raids on Tokyo and other cities mainly used precision bombing tactics and high explosive bombs, and were largely unsuccessful due to adverse weather conditions and a range of mechanical problems which affected the B-29s. These failures led to the head of the Command being relieved in January 1945. Major General Curtis LeMay, the commander of XX Bomber Command, replaced General Haywood S. Hansell. Arnold and the Twentieth Air Force's headquarters regarded the campaign against Japan up to that time as unsuccessful, and LeMay understood that he would also be relieved if he failed to deliver results. He believed that changing the emphasis from precision bombing to area bombing was the most promising option to turn the XXI Bomber Command's performance around.
Preparations
Early incendiary raids on Japan
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. The plans for the strategic bombing offensive against Japan developed in 1943 specified that it would transition from a focus on the precision bombing of industrial targets to area bombing from around halfway in the campaign, which was forecast to be in March 1945.
Preparations for firebombing raids against Japan began well before March 1945. In 1943, the USAAF tested the effectiveness of incendiary bombs on adjoining German and Japanese-style domestic building complexes at the Dugway Proving Ground. These trials demonstrated that M69 incendiaries were particularly effective at starting uncontrollable fires. These weapons were dropped from B-29s in clusters, and used napalm as their incendiary filler. After the bomb struck the ground, a fuse ignited a charge which first sprayed napalm from the weapon, and then ignited it. Prior to March 1945, stockpiles of incendiary bombs were built up in the Mariana Islands. These were accumulated on the basis of XXI Bomber Command plans which specified that the B-29s would each carry 4 short tons (3.6 t) of the weapons on 40 percent of their monthly sorties. 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.
Several raids were conducted to test the effectiveness of firebombing against Japanese cities. A small incendiary attack was made against Tokyo on the night of 29/30 November 1944, but caused little damage. Incendiaries were also used as part of several other raids. On 18 December, 84 XX Bomber Command B-29s conducted an incendiary raid on the Japanese-occupied Chinese city of Hankou which caused extensive damage. That day, the Twentieth Air Force directed XXI Bomber Command to dispatch 100 B-29s on a firebombing raid against Nagoya. An initial attack took place on 22 December which was directed at an aircraft factory and involved 78 bombers using precision bombing tactics. Few of the incendiaries landed in the target area. On 3 January, 97 Superfortresses were dispatched to firebomb Nagoya. This attack started some fires, which were soon brought under control by firefighters. The success in countering the raid led the Japanese authorities to become over-confident about their ability to protect cities against incendiary attacks. The next firebombing raid was directed against Kobe on 4 February, and bombs dropped from 69 B-29s started fires which destroyed or damaged 1,039 buildings.
On 19 February, the Twentieth Air Force issued a new targeting directive for XXI Bomber Command. While the Japanese aviation industry remained the primary target, the directive placed a stronger emphasis on firebombing raids against Japanese cities. The directive also called for a large-scale trial incendiary raid as soon as possible. This attack was made against Tokyo on 25 February. A total of 231 B-29s were dispatched, of which 172 arrived over the city; this was XXI Bomber Command's largest raid up to that time. The attack was conducted in daylight, with the bombers flying in formation at high altitudes. It caused extensive damage, with almost 28,000 buildings being destroyed. This was the most destructive raid to have been conducted against Japan, and LeMay and the Twentieth Air Force judged that it demonstrated that large-scale firebombing was an effective tactic.
The failure of a precision bombing attack on an aircraft factory in Tokyo on 4 March marked the end of the period in which XXI Bomber Command primarily conducted such raids. Civilian casualties during these operations had been relatively low; for instance, all the raids against Tokyo prior to 10 March caused 1,292 deaths in the city.
Preparations to attack Tokyo
In early March, LeMay judged that further precision bombing of Japanese industrial targets was unlikely to be successful due to the prevailing weather conditions over the country. There were on average only seven days of clear skies each month, and an intense jet stream made it difficult to aim bombs from high altitudes. Due to these constraints, LeMay decided to focus XXI Bomber Command's attacks on Japanese cities. The general directions issued to LeMay permitted such operations, which he decided on his own initiative. On 5 March XXI Bomber Command's personnel were advised that no further major attacks would be scheduled until 9 March. During this period LeMay's staff finalized plans for the attack on Tokyo. At a meeting on 7 March, LeMay agreed to conduct an intense series of raids against targets on the island of Honshu between 9 and 22 March as part of the preparations for the invasion of Okinawa on 1 April.
LeMay decided to adopt radically different tactics for this campaign. Analysis by XXI Bomber Command staff of the 25 February raid concluded that the incendiary bombs had been dropped from too high an altitude, and attacking at lower levels would both improve accuracy, and enable the B-29s to carry more bombs as the denser air at low altitude put less strain on the engines and required less weight of fuel. This would also expose them to the Japanese air defenses, but LeMay judged that poor Japanese fire control tactics meant that the additional risk was moderate. As weather conditions over Japan tended to be more favorable at night and the LORAN systems the B-29s used to navigate were more effective after dusk, it was also decided to conduct the attack at night, individually rather than in formations, as it was not possible for the B-29s to keep station without daytime visibility. Flying individually would also require less fuel, as the pilots would not need to make constant adjustments to remain in formation. USAAF intelligence had determined that the Japanese had only two night fighter units, which were believed to pose little threat, so LeMay decided to remove all the B-29s' guns and gunners other than those at the rear to reduce aircraft weight and further increase the bomb load that could be carried. All these fuel savings and other weight reductions allowed the Superfortresses to carry twice their usual bomb load.
While LeMay made the ultimate decision to adopt the new tactics, he acknowledged that his plan combined ideas put forward by many officers. On 7 March, some of the B-29 crews flew training missions during which they practiced using radar to navigate and attack a target from low altitude, without the reason being explained.