The 'Bombing of Yawata' marked the start of the US Army Air Forces' strategic bombing campaign against the Japanese home islands, and was the first such raid to employ strategic bombers (15/16 June 1944).

The raid was undertaken by 75 Boeing B-29 Superfortress four-engined heavy bombers staging from bases in China. Only 47 of these aircraft dropped bombs near the raid’s primary target, the Imperial Iron and Steel Works at Yawata in northern Kyushu, and little damage was caused. Five of the B-29 bombers were lost in accidents during the operation and two were destroyed by Japanese aircraft.

While the raid did not achieve its aims, it raised Japanese civilians' awareness that their country was being defeated and received positive media coverage in the USA. Intelligence gathered by the B-29 aircraft also revealed weaknesses in Japan’s air defences, and the raid was followed by many others on targets in Japan. Yawata was attacked again by B-29 bombers operating from China on 20 August 1944, and much of the city was destroyed in a firebombing raid conducted by B-29 warplanes based in the Mariana islands group on 8 August 1945.

The US Army Air Forces' first raid on Japan took place on 18 April 1942 when 16 North American B-25 twin-engined Mitchell medium bombers flying from an aircraft carrier attacked several cities in the course of 'Conceal', generally known as the 'Doolittle Raid'. Although this raid caused little damage, it boosted morale in the USA, and the Japanese responded to the attack by increasing the number of fighter units based in the home islands and by conducting the 'Mi' offensive in the Pacific Ocean which ended in defeat during the 'Battle of Midway'. The USAAF could mount no further attacks on the Japanese home islands after this raid, however, as none of its land-based bombers had sufficient range to reach this area from bases in China or the Pacific until the B-29 was ready for combat.

The B-29 had a difficult introduction into service. Work began on the design of this heavy bomber began early in 1940, and the first prototype flew on 21 September 1942. The Superfortress was the largest combat aircraft of World War II and combined the ability to carry a heavy maximum bomb load, long range and powerful defensive armament. The B-29 also incorporated a number of new features, such as pressurised accommodation and remotely controlled turrets. While 1,664 B-29 bombers had been ordered by the USAAF before the type first flew, the B-29’s development was set back by several months when the second prototype crashed on 18 February 1943 and as problems with the design were gradually solved. The 58^th Bombardment Wing was formed in June 1943 to operate the USAAF’s first B-29 bombers, but it did not begin to receive its aircraft until October. The slow delivery of the B-29 and mechanical problems meant that the unit lagged behind its training schedule and became capable of deployment only in March 1944, after the so-called 'Battle of Kansas' programme began to produce combat-ready aircraft.

Late in 1943, the US Joint Chiefs-of-Staff approved a proposal to begin a strategic air campaign against the Japanese home islands and East Asia by basing B-29 bombers in India and establishing forward airfields in areas of China. This 'Matterhorn' strategy required the construction of large runways near Chengdu in inland China, which would be supplied by Allied cargo aircraft and be used to refuel B-29 bombers flying from bases in Bengal on their way to bomb targets in Japan. The XX Bomber Command was assigned responsibility for this effort, and its ground crew began to leave the USA for India by sea in December 1943. The 20^th Army Air Force was created in April 1944 to oversee all B-29 operations. In an unprecedented move, the commander of the USAAF, General Henry H. Arnold, took personal command of this unit and ran it from the Pentagon. Brigadier General LaVerne G. Saunders’s 58^th Bombardment Wing was the XX Bomber Command’s main combat unit, and its movement from Kansas to India took place between April and the middle of May. While the wing had not completed its training at the time it departed for India, its combat groups were more experienced than most newly deployed USAAF bomber units.

After establishing itself in India, the XX Bomber Command under the command of Brigadier General Kenneth B. Wolfe undertook various tasks to prepare for raids against Japan. Foremost among these was the stockpiling of fuel at the airfields in China. Until late 1944, aircraft of the USAAF’s Air Transport Command did not transport fuel for XX Bomber Command, and the task was therefore undertaken by the B-29 themselves. This arrangement proved inefficient, however, as 12 B-29 sorties between India and China were needed to transport enough fuel and other supplies to enable one heavy bomber to fly a round trip between China and Japan. It therefore took longer than expected to build up sufficient stockpiles in China to allow the start of B-29 operations. Moreover, continued technical problems with the bomber, and in particular its Wright R-3350 engines, resulted in many of the XX Bomber Command’s aircraft being unserviceable and in need of modification at all times.

The XX Bomber Command flew its first combat operation on 5 June 1944, when 98 B-29 bombers were despatched from bases in India to attack targets in Bangkok, Thailand, as a 'dress rehearsal' for more ambitious operations against Japan and targets in South-East Asia. Although little damage was done and five B-29 bombers were lost in flying accidents or to technical faults, the operation was rated successful by the XX Bomber Command as it provided useful combat experience for the bomber crews, as well as data on how the B-29 performed in action.

On 6 June, Wolfe received a message from Arnold informing him that the Joint Chiefs-of-Staff wished a raid to be conducted against Japan at a time as soon as possible. The goals of this operation were to relieve pressure on the Chinese forces, which were being attacked by the Japanese, and to support the invasion of Saipan in the 'Forager' amphibious operation against the Mariana islands group. Arnold’s message also asked how many B-29 bombers could be despatched on 15 and 20 June. At the time, the first raid on Japan was tentatively scheduled for 23 June, when sufficient supplies were expected to be available in China to support 100 B-29 sorties. Wolfe replied to the effect that 50 B-29 bombers could be used on 15 June and 55 if the operation was conducted on 20 June. Arnold regarded these numbers as too low and directed that a raid by at least 70 B-29 bombers be flown against Japan on 15 June. Following this order, XX Bomber Command’s B-29 bombers and transport aircraft embarked on an intensive effort to move fuel to China. Further fuel supplies were made available to the heavy bombers by reducing the activities of USAAF fighter units based in China. During the same period, the command’s ground crews reconditioned as many B-29 bombers as possible to improve their reliability.

The target selected was the Imperial Iron and Steel Works at Yawata, an industrial city about 1,600 miles (2575 km) from Chengdu. This was the single most important facility in Japan’s steel industry as it produced 24% of the country’s total output of rolled steel. The facility was dependent on three coke plants, and the largest of these was chosen as the designated aiming point for the B-29 bombers. Nearby Laoyao harbour, which was an important industrial port, was designated as the raid’s secondary target. The selection of Yawata’s steel works accorded with a decision made by the 20^th Army Air Force on 1 April 1944, which assigned the highest priority to attacking Japan’s steel and coke industry. It was decided to undertake the raid at night, with each B-29 bombing individually, as the aircraft lacked the range needed to conduct a more fuel-intensive formation flight between the forward air bases and Yawata.

Despite the conception and implementation of an elaborate deception plan, which included planted news stories claiming that B-29 aircraft would be deployed as bombers in Europe but only as armed transports in the China-Burma-India Theatre, the Japanese military detected the preparation of B-29 bases in India and China. Moreover, Japanese agents in China reported on all B-29 movements, giving hours of warning time before raids on the home islands. The Japanese intelligence services deduced that once logistical preparations had been completed, the heavy bombers would attack factories in the northern part of Kyushu island, and that the first raid would be made at night. On 26 April, Japanese fighters encountered a B-29 for the first time, when two Nakajima Ki-43 'Oscars' single-engined fighters attacked and damaged a lone B-29 flying near the China/India border.

The Japanese military began transferring fighter aircraft from China and the Pacific to the home islands early in 1944 in anticipation of B-29 raids. In June 1944, Yawata lay within the Western District of Japan’s four regional defence commands. The 19^th Air Brigade was formed in June 1944 to command fighter units in the Western District and comprised the 4^th and 59^th Air Regiment: the 4^th Air Regiment was stationed at Ozuki airfield and equipped with 35 Kawasaki Ki-45 Toryu 'Nick' twin-engined heavy fighters, of which 25 were operational in mid-June, and had the brigade’s best-trained pilots, and the inexperienced 59^th Air Regiment was based at Ashiya Fukuoka airfield and operated 25 Kawasaki Ki-61 Hien 'Tony' single-engined fighters, of which only about seven or eight were operational. In addition, Yawata and northern Kyushu were defended by anti-aircraft artillery units and barrage balloons, and radar stations and a network of lookout posts provided early warning.

The 19^th Air Brigade's primary mission was the defence of the industrial facilities in the northern part of Kyushu, and particularly the steel works at Yawata. The brigade’s plans for the defence of the Western District called for its interceptor aircraft to be concentrated over Yawata and not move far from the area. While this inflexible deployment was considered unsatisfactory by the 19^th Air Brigade, it was deemed necessary as few aircraft were available, the only searchlight units needed to facilitate night operations were stationed near Yawata, and the northern part of Kyusu was regarded by the Imperial Japanese army as being the most important region in the Western District. Before the raid on Yawata, the 19^th Air Brigade undertook joint planning with anti-aircraft units and implemented a training programme which included practice in the rapid response to alerts and in night flying.

The 58^th Bombardment Wing’s B-29 bombers began moving from India to the forward bases in China on 13 June. By 15 June, 83 bombers had reached the four forward airfields around Chengdu, though at least 12 turned back before reaching China, and another crashed, causing the death of its entire crew. Each of the aircraft had departed India carrying 4,000 lb (1814 kg) of 500-lb (227-kg) bombs they would use in the raid. A large number of staff officers, including eight generals, also travelled to Chengdu to observe the operation, but were not allowed to participate in the raid. The bomber crews were joined by eight journalists and three news photographers, however. At the time, the USAAF had few recent photographic images of Japanese industrial areas, and the bomber crews were briefed on Yawata using maps and photographs from the late 1920s and early 1930s.

The B-29 bombers began to depart their bases at 16.16 on 15 June. The raiding force was led by Saunders, the 58^th Bombardment Wing’s commander. One aeroplane crashed immediately after taking off, but without suffering casualties, and a another four turned back with mechanical problems. The remaining 70 aircraft proceeded on a direct course to Okino island, where they turned for the approach to Yawata. Each of the 58^th Bombardment Wing’s four groups sent two aircraft ahead to mark the target and the other aircraft flew in a long bomber stream; both of these tactics had been adopted from those used by the British Bomber Command in Europe. The raiders were detected by Japanese army and army air force units in China, which passed their reports to the 19^th Air Brigade, which estimated that the bombers were bound for northern Kyushu, which they would reach at about 00.00. A radar station and look-out posts on Cheju-Do subsequently detected the bombers between 23.31 and 00.30. An air raid alarm was issued at 00.24, and 24 aircraft of the 4^th Air Regiment began to take off three minutes later to patrol over northern Kyushu. The 59^th Air Regiment was not scrambled, as its pilots had not worked with those of the 4^th Air Regiment in night operations, its aircraft were suffering from mechanical problems, and it was feared that the B-29 bombers would sight and attack the base at Ashiya.

The US bombers started to arrive over Yawata at 00.38, and the attack on the city lasted almost two hours. Only 15 of the US aircraft were able to aim their bombs visually, as the city was blacked out and obscured by smoke or haze, and the other 32 bombed by radar. Two more B-29 bombers attacked Laoyao harbour and another five struck targets of opportunity. In all, 107 tons of bombs were dropped during the raid. After the first bombs had been released, regular updates on the operation were transmitted to the 20^th Army Air Force’s headquarters in Washington, from where they were relayed to Arnold, who was in London at the time. The raiders were met with heavy but inaccurate anti-aircraft fire, and the searchlights stationed around Yawata were ineffective. The 4^th Air Regiment achieved the only air-to-air 'kill' of the night when one of its fighters shot down a B-29, but the regiment’s other aircraft struggled to make contact with the bombers and achieved few interceptions.

The bombers' return flights to China were largely uneventful. One aeroplane was strafed and destroyed by Japanese aircraft after landing at Neihsiang with engine trouble, and another two aircraft crashed with the loss of their crews and a correspondent from the Newsweek magazine. Overall, the US losses in the raid were seven B-29 bombers destroyed and another six damaged by anti-aircraft fire, and 57 airmen and one journalist were killed aboard these aircraft. Many of the B-29 bombers were stranded in China for several days after the raid by fuel shortages and returned to India only after Wolfe borrowed 15,000 US gal (56780 litres) of fuel from the 312^th Fighter Wing’s supplies. During this period, the bombers were highly vulnerable to Japanese retaliatory raids, but none came about.

Little damage was caused by the raid on Yawata. On 18 June, an aeroplane of the 14^th Army Air Force overflew the city and photographed the target area. These photos showed that only a single bomb had landed within the Imperial Iron and Steel Works complex, where it had hit a power house 3,700 ft (1130 m) from the nearest coke oven. Light damage had also been inflicted on Kokura Arsenal and other industrial and civilian buildings in the area. Despite a USAAF policy of encouraging factual reporting of B-29 operations, the raid’s results were overstated in the US media. The relatively light combat losses suffered by the raiders and electronic intelligence collected by the bombers revealed the ineffectiveness of Japanese radar and air defences, and as a result the USAAF despatched a single photo-reconnaissance B-29 to overfly much of Japan and Korea on 21 June. This sortie was successful and greatly improved US intelligence on these areas.

The Yawata raid revealed serious shortcomings in Japan’s air defences. While the 19^th Air Brigade initially claimed to have shot down eight bombers and damaged another four, it was soon clear that only two of the bombers had been destroyed. This loss ratio was considered too low to defeat attacks on the home islands. The raid demonstrated that Japan had too few air bases and that there were inadequate numbers of aircraft for night operations. It was also found that the Ki-45 fighter was not well suited to the interception of the B-29 as it was slower than the bomber, too lightly armed, and most aircraft lacked radar. While the air-raid alert system had proved successful in this instance, the radars which detected the US aircraft had been unable to determine their altitude, and it was decided that radar coverage had to be expanded. The performance of the 131^st Anti-Aircraft Regiment during the raid was judged to be so poor that its commander was transferred to Manchuria. News reports of the Yawata raid and of the successful US landing on Saipan during the same day also indicated to the majority of Japanese civilians that the war was not going well. Moreover, in response to the raid Japanese government ministers urged families living in the country’s four major cities to evacuate their children to rural areas.

The raid on Yawata marked the beginning of the USAAF’s strategic bombing campaign against Japan. The city was struck again by B-29 bombers during daylight and night raids on 20 August, but no serious damage was suffered. The XX Bomber Command flew 49 raids from its bases in China and India between June 1944 and March 1945, of which nine were made on targets in the Japanese home islands, but 'Matterhorn' failed to achieve its goals. Despite initial problems, the XXI Bomber Command’s operations from the Mariana islands group, which began on 28 October 1944, proved considerably more effective. As a result, the XX Bomber Command was transferred to the Mariana islands group early in 1945. Yawata was targeted again by B-29 bombers on 8 August 1945, two days after the atomic bombing of Hiroshima. On this day the city was attacked by 221 B-29 bombers, escorted by three groups of Republic P-47N Thunderbolt single-engined fighters, including the 318^th Fighter Group based on Ie Shima island off the coast of Okinawa. The bombers were armed with incendiary bombs, and the resulting firestorm destroyed 21% of Yawata’s urban area.