Air Raids On Japan - Initial Attacks From The Mariana Islands

Initial Attacks From The Mariana Islands

United States Marine Corps and Army forces captured the Japanese-held islands of Guam, Saipan and Tinian in the Mariana Islands between June and August 1944. USAAF and US Navy engineers subsequently constructed six airfields on the islands to accommodate hundreds of B-29s. These bases were more capable of supporting an intensive air campaign against Japan than those in China as they could be easily supplied by sea and were 1,500 miles (2,400 km) south of Tokyo, which allowed B-29s to strike most areas in the home islands. Japanese aircraft made several attacks on the airfield at Saipan while it was under construction.

The Twentieth Air Force's XXI Bomber Command began arriving in the Mariana Islands during October 1944. The Command was led by Brigadier General Haywood S. Hansell, who had also participated in Eighth Air Force operations against Germany. XXI Bomber Command B-29s flew six practice missions against targets in the Central Pacific during October and November in preparation for their first attack on Japan. On 1 November, an F-13 photo reconnaissance variant of the B-29 from the 3d Photographic Reconnaissance Squadron overflew Tokyo; this was the first American aircraft to fly over the city since the Doolittle Raid. Further F-13 sorties were conducted during early November to gather intelligence on aircraft factories and port facilities in the Tokyo–Yokosuka area. The F-13s were generally able to evade the heavy anti-aircraft fire they attracted and the large numbers of Japanese fighters that were scrambled to intercept them as they flew at both high speed and high altitude.

XXI Bomber Command's initial attacks against Japan were focused on the country's aircraft industry. The first attack, codenamed Operation San Antonio I, was made against the Musashino aircraft plant in the outskirts of Tokyo on 24 November 1944. Only 24 of the 111 B-29s dispatched attacked the primary target, and the others bombed port facilities as well as industrial and urban areas. The Americans were intercepted by 125 Japanese fighters but only one B-29 was shot down. This attack caused some damage to the aircraft plant and further reduced Japanese civilians' confidence in the country's air defenses. In response, the IJAAF and IJN stepped up their air attacks on B-29 bases in the Mariana Islands from 27 November; these raids continued until January 1945 and resulted in the destruction of 11 Superfortresses and damage to another 43 for the loss of probably 37 Japanese aircraft. The IJA also began launching fire balloons against the United States during November. This campaign caused little damage and was abandoned in March 1945. By this time 9,000 balloons had been dispatched but only 285 were reported to have reached the Contiguous United States.

The next American raids on Japan were not successful. XXI Bomber Command attacked Tokyo three times between 27 November and 3 December; two of these raids were made against the Musashino aircraft plant while the other targeted an industrial area using M-69 Incendiary cluster bombs, specifically developed to damage Japanese urban areas. The aircraft plant attacked on 27 November and 3 December was only lightly damaged as high winds and clouds prevented accurate bombing. The incendiary raid conducted on the night of 29/30 November by 29 Superfortresses burnt out one tenth of a square mile and was also judged to be unsuccessful by the Twentieth Air Force's headquarters.

Four of XXI Bomber Command's next five raids were made against targets in Nagoya. The first two of these attacks on 13 and 18 December used precision bombing tactics, and damaged the city's aircraft plants. The third raid was a daylight incendiary attack which was conducted after the Twentieth Air Force directed that 100 B-29s armed with M-69 bombs be dispatched against Nagoya to test the effectiveness of these weapons on a Japanese city. Hansell protested this order as he believed that precision attacks were starting to produce results and moving to area bombardment would be counterproductive, but agreed to the operation after he was assured that it did not represent a general shift in tactics. Despite the change in armament, the 22 December raid was planned as a precision attack on an aircraft factory using only 78 bombers, and bad weather meant that little damage was caused. XXI Bomber Command raided the Musashino aircraft plant in Tokyo again on 27 December, but did not damage the facility. On 3 January 1945, 97 B-29s were dispatched to conduct an area bombing raid on Nagoya. This attack started several fires, but these were quickly brought under control.

In late December 1944 Arnold, who was disappointed with the results XXI Bomber Command had achieved, decided to relieve Hansell of his command and replace him with LeMay. Arnold made this decision as he wanted the command to rapidly produce results. In addition, Hansell's preference for precision bombing was no longer in accordance with the views of the Twentieth Air Force headquarters, which wished to place a greater emphasis on area attacks. Due to his success in improving XX Bomber Command's performance, LeMay was believed to be capable of solving the problems that were affecting XXI Bomber Command. Hansell was informed of Arnold's decision on 6 January, but remained in his position until mid-January. During this period, XXI Bomber Command conducted unsuccessful precision bombing attacks on the Musashino aircraft plant in Tokyo and a Mitsubishi Aircraft Works factory in Nagoya on 9 and 14 January respectively. The last attack planned by Hansell was more successful, however: a force of 77 B-29s crippled a Kawasaki Aircraft Industries factory near Akashi on 19 January. During XXI Bomber Command's first three months of operations it suffered an average loss rate of 4.1 percent of aircraft dispatched in each raid.

In late January 1945 the Imperial General Headquarters belatedly adopted a civil defense plan to counter the American air raids. This plan assigned responsibility for fighting fires to community councils and neighborhood groups as the professional firefighting units were short-handed. Civilians were to observe a blackout from 10:00 pm. Japanese positions in the Bonin Islands were normally able to provide an hour's warning of American raids and air raid sirens were sounded in cities threatened by attack.

The first attacks conducted under LeMay's leadership achieved mixed results. XXI Bomber Command flew six major missions between 23 January and 19 February with little success, though an incendiary raid against Kobe on 4 February caused significant damage to the city and its main factories. Moreover, while improved maintenance procedures implemented by LeMay reduced the number of B-29s that had to return to base during raids due to technical problems, the command suffered a loss rate of 5.1 percent in these operations. From 19 February to 3 March, XXI Bomber Command conducted a series of precision bombing raids on aircraft factories that sought to tie down Japanese air units so they could not participate in the Battle of Iwo Jima. However, these attacks were frustrated by high winds and cloud cover and little damage was inflicted. A firebombing raid conducted against Tokyo by 172 B-29s on 25 February was considered successful as it burnt or damaged approximately one square mile of the city's urban area. This attack was a large-scale test of the effectiveness of firebombing.

Several factors explain the poor results of XXI Bomber Command's precision bombing campaign. The most important of these was the weather; the American raiders frequently encountered cloudy conditions and high winds over Japan which made accurate bombing extremely difficult. Moreover, the bomber forces often had to pass through severe weather fronts between the Mariana Islands and Japan and these acted to break up formations and cause navigation problems. XXI Bomber Command's effectiveness was also limited by poor B-29 maintenance practices and over-crowding at its airfields – these factors reduced the number of aircraft which were available for operations and complicated the process of launching and recovering the bombers. By March 1945 the USAAF's commanders were highly concerned about the failure of the campaigns mounted from China and the Mariana Islands, and believed that the results to date made it difficult to justify the high costs of the B-29 program and also threatened their goal of demonstrating the effectiveness of independent air power.