The XXI Bomber Command was a unit of the Twentieth Air Force in the Mariana Islands for strategic bombing during World War II.
The command was established at Smoky Hill Army Air Field, Kansas on 1 March 1944. After a period of organization and its assigned groups receiving their B-29 Superfortress aircraft, the command transferred first to Peterson Field, Colorado, then deployed to the central Pacific, being headquartered at Harmon Field, Guam, in the Mariana Islands.
Its assigned units engaged in very long-range bombardment operations, primarily against Japan until mid-July 1945.
History The Marianas chain of islands, consisting primarily of Saipan, Tinian, and Guam, were considered as being ideal bases from which to launch B-29 Superfortress operations against Japan. The islands were about from Tokyo, a range which the B-29s could just about manage. Most important of all, they could be put on a direct supply line from the United States by ship. In August 1944, Major general Haywood S. Hansell, Jr was directed to take over command of the organization.Marshall,
Serious planning for the movement of the XXI Bomber Command's B-29s from their Second Air Force training bases in Kansas to newly constructed combat airfields on Saipan, Tinian and Guam began in April 1944. The construction and defense of the airfields would be the United States Navy's responsibility, as would logistical support. Before the B-29s could begin operating against Japan from the Marianas, the islands first had to be taken away from the Japanese.
This began with the Battle of Saipan on 11 June 1944 when a four-day naval and air bombardment of the island began. On 15 June United States Marine Corps units stormed ashore, followed a day later by United States Army units. After several weeks of heavy fighting, during which over 3,000 American and 24,000 Japanese people died, the island was finally declared secure on 9 July.
The seizure of Saipan enabled invasions of Guam and Tinian to proceed, which were attacked on 21 and 24 July respectively. Tinian was secured on 1 August and Guam was secured on 10 August.
Airfield construction Construction of the B-29 airfields on Saipan began almost immediately, even while the fighting was still going on. Naval Construction Battalions (NCBs), the "SeaBees" began construction at a former Japanese airstrip called Aslito. This was later renamed Isley Field, after Navy Commander Robert H. Isely (his name was misspelled and the incorrect version stuck). The SeaBees did not meet their schedule, but came very close. In a little over three months they had built a support base and airfield on Saipan, capable of supporting the 240 B-29s of the 73d Bombardment Wing and their logistical support units.Mann
On Tinian, the SeaBees built the largest bomber base ever, North Field. The 6th Naval Construction Brigade built four runways for the 313th Bombardment Wing, and all required infrastructure; then went to the west end of the island and at West Field laid down two 8,500-foot runways for the 58th Bombardment Wing.
On Guam the 5th NCB built North Field for the 314th Bombardment Wing and Northwest Field for the 315th Bombardment Wing.
Initial B-29 Operations
The 73d Bombardment Wing was ordered to the Marianas rather than to the CBI Theater after its training with Second Air Force in Kansas. The first B-29 arrived at Isley Field, Saipan on 12 October 1944. By 22 November, over 100 B-29s were at Isley Field. XXI Bomber Command was assigned the mission of destroying the aircraft industry of Japan in a series of high-altitude, daylight precision attacks. However, General Hansell was fully aware that his crews still lacked the necessary experience to carry out such missions.
In late October and early November 1944, a series of tactical raids were carried out as training exercises for the crews. On 27 October, 18 B-29s attacked lightly defended Japanese installations on Truk. The submarine pens at Truk were the target, and four Superfortresses had to abort because of the usual engine problems, and combat formations were scrappy. The bombing results were mediocre, with only nine planes bombing the primary target and only a few bombs hitting it. The same two groups returned to Truk on 30 October with even fewer bombs landing on the target. The third try, on 2 November, was briefed as a radar bombing mission. Again the results were indifferent, with bombs scattered all over the general target area.
Aware that there was now a new threat, Japanese aircraft based on Iwo Jima staged a low-level raid on Isley Field on 2 November, damaging several B-29s on the ground. Retaliatory strikes were ordered against the two enemy airfields on Iwo Jima on 5 and 11 November with the 497th and 498th Bombardment Groups dispatched to bomb airfields there, but the results were once again poor. As in the XX Bomber Command Operation Matterhorn bombing campaign from India, the B-29s were in danger of being dissipated in tactical missions and even these were not all that successful.
In order to properly plan missions to Japan, up-to-date reconnaissance photos of the proposed targets were needed. Other than information which was used during the Doolittle Raid in 1942, there was scant information about the locations of Japanese industry, especially the aircraft industry. On 1 November 1944, two days after arriving on Saipan, A 3d Photographic Reconnaissance Squadron F-13A Superfortress (photo reconnaissance-configured B-29) took off bound for Tokyo. The 3d PRS attached to the 73d Bombardment Wing. The aircraft flew over Tokyo at for 35 minutes taking picture after picture. A few fighters made it up to the camera plane's altitude, but did not attack. These photos, along with other intelligence gave the XXI Bomber Command the locations of the Japanese aircraft manufacturing plants and enabled mission planners to plan missions for the combat crews to attack. In honor of his mission, the aircraft was named "Tokyo Rose".
The 3d PRS continued to fly single plane missions to Japan, taking high altitude pre-strike target planning photos and post-strike damage assessment photos. The losses incurred by the squadron in this type of activity were relatively light. Seldom were the Japanese able to get fighters up to in time to intercept the F-13As.Birdsall,
All four groups of the 73d Wing were sent on their first mission to Japan on 24 November with 111 planes airborne. The target was the Nakajima Aircraft Engine Plant at Musashino in the arsenal sector of Tokyo. Also, for the first time, the B-29 encountered the Jet stream, which was a high-speed wind coming out of the west at speeds as high as at precisely the altitudes at which the bombers were operating. This caused the bomber formations to be disrupted and made accurate bombing impossible. Because of the jet stream winds and bad weather, only 24 planes, from the leading 497th Bomb Group, attacked the primary target; the majority dropped their bombs on the secondary target of the Tokyo Docks.
The group returned to Musashino on the 27th and closed out November with a raid on the Tokyo Industrial Area and Docks. The pace picked up the next month, with a return to Musashino on 3 December. Again, poor bombing results were achieved, with the jet stream winds scattering the bomb drops and the aircraft in the formation, with the result of not much damage to the enemy being done. 8 December saw 82 planes attacking the Iwo Jima airfields (Motoyama Nos 1 and 2). Then it was back to attacking Japan, hitting Nagoya on 18 and 22 December. The airfields on Iwo Jima were revisited on 24 December and Tokyo the final target of the month on 27 December.
In addition to the wing strikes, December saw the initiation of another type of single plane mission: the weather strike. These were missions to Japan to collect weather data and drop nuisance bombs on Japanese cities. Again, these were high altitude missions with surprisingly low losses. The 3d PRS lost two planes in December. Out of the 75 weather strike missions flown in December, there were only three losses. During the same time period the 73rd Wing lost 21 planes to all causes on the six multi-plane raids by the wing as a whole.
The pace continued to quicken for the 73d in January. Musashino on 9 January cost six planes; Nagoya on 14 January, another five. One weather strike, out of 83 flown, was lost on 10 January, but help was on the way as new B-29s from the United States were arriving almost daily and new groups were arriving in the Marianas. The 313th Bombardment Wing, operating from Tinian, sent 44 planes to Pagan Island on 16 January, another 33 to Truk on 21 and 28 January to attack the Iwo Jima airfields on 24 January. Thirty-three more returned to Iwo Jima on 29 January. The 313th's 504th and 505th groups joined in the attack on Kobe on 4 February, while on 9 February their sister groups, the 6th and 9th, made their initial training mission against the Moen Island airfield on Truk.
US Marines landed on Iwo Jima 19 February 1945 with a mission to seize the island to build emergency landing airfields for XXIst Bomber Command as well as fighter airfields for VII Fighter Command. On 25 March the Battle of Iwo Jima was declared over and the island secured, although mopping up continued until June. Construction Battalions extended and transformed the former Japanese fields to accommodate B-29s and the first AAF units moved in during the beginning of March.
B-29 Incendiary Operations
The high-altitude bombing raids on Japan carried out by the command were not causing significant damage to the targets, primarily due to the jet stream winds over the islands. The failure of the command to successfully carry out its mission was causing severe problems with the War Department in Washington, which had planned to eliminate the Japanese industrial base by the same strategic bombing techniques which were being carried out in Europe. Also General Hap Arnold and the AAF command staff which were aware of the Manhattan Project, and planned on using the B-29 to drop the Atomic Bombs, were concerned that the B-29 would be unable to carry out that highly secret mission.
Since little progress in the bombing campaign was being made, Arnold recalled Hansell and moved General Curtis LeMay from the inactivating XX Bomber Command in India to take over XXI Bomber Command on Saipan. LeMay arrived in the Marianas on 20 January 1945. LeMay had analyzed the structure of the Japanese economy, which depended heavily on cottage industries housed in cities close to major industrial areas and issued new orders on 19 February. His plan was to destroy the feeder industries, that would slow or halt the flow of vital components to the central manufacturing plants, and disorganize the production of weapons vital to Japan. LeMay decided to do this by using incendiary bombs rather than purely high-explosive bombs, which would, it was hoped, cause general conflagrations in large cities like Tokyo or Nagoya, spreading to some of the priority targets. In addition, LeMay had concluded that the effects of the jet stream, cloud cover, and high operating altitudes were to blame for the failure of the B-29 raids to do any significant damage to the Japanese war industry. The initial raids against Japan had taken place at high altitudes in order to stay above anti-aircraft fire and the effective altitude of defending fighters. LeMay suggested that high-altitude, daylight attacks be phased out and replaced by low-altitude, high-intensity incendiary raids at nighttime. The aircraft would attack individually, which meant that no formation assembly over the base at the start of the mission or along the way would be needed. This would extend the range of the aircraft and allow them to reach targets in northern Honshu and Hokkaido.