Twentieth Air Force

Twentieth Air Force
Twentieth Air Force emblem Part of Air Force Global Strike Command
Active	4 April 1944
Country	United States of America
Branch	United States Air Force
Part of	Air Force Global Strike Command
Garrison/HQ	Francis E. Warren Air Force Base
Engagements	World War II Asiatic-Pacific Campaign (1944–1945) Korean Service (1950)
Commanders
Current commander	Maj Gen C. Donald Alston
Notable commanders	Curtis LeMay

An LGM-30 Minuteman III missile soars in the air after a test launch

The Twentieth Air Force (20 AF) is a numbered air force of the United States Air Force Global Strike Command (AFGSC). It is headquartered at F.E. Warren Air Force Base, Wyoming.

20 AF's primary mission is Intercontinental Ballistic Missile (ICBM) operations. The Twentieth Air Force commander is also the Commander, Task Force 214 (TF 214), which provides alert ICBMs to the United States Strategic Command (USSTRATCOM).

Established on 4 April 1944 at Washington D.C, 20 AF was a United States Army Air Forces combat air force deployed to the Pacific Theater of World War II. Operating initially from bases in India and staging though bases in China, 20 AF conducted strategic bombardment of the Japanese Home Islands. It relocated to the Mariana Islands in late 1944, and continued the strategic bombardment campaign against Japan until the Japanese Capitulation in August 1945. The 20 AF 509th Composite Group conducted the Atomic Bomb attacks on Hiroshima and Nagasaki, Japan, in August 1945.

Inactivated on 1 March 1955, the command was reactivated 1 September 1991, as a component of the Strategic Air Command (SAC) and became operationally responsible for all land-based Intercontinental Ballistic Missiles.

20 AF is commanded by Maj Gen C. Donald Alston.

Overview

20 AF provides on-alert, combat ready ICBMs to the president. Combined with the other two legs of the Triad, bombers and submarines, STRATCOM forces protect the United States with an umbrella of deterrence.

Twentieth Air Force headquarters is unique in that it has dual responsibilities to Air Force Global Strike Command and United States Strategic Command. As the missile Numbered Air Force for AFGSC, 20th Air Force is responsible for maintaining and operating the Air Force's ICBM force. Designated as STRATCOM's Task Force 214, 20th Air Force provides on-alert, combat ready ICBMs to the president. Combined with the other two legs of the Triad, bombers and submarines, STRATCOM forces protect the United States with an umbrella of deterrence.

Organization

• Headquarters, Francis E. Warren AFB, Wyoming
• 90th Missile Wing, Francis E. Warren AFB, Wyoming
  • 319th Missile Squadron
  • 320th Missile Squadron
  • 321st Missile Squadron
• 91st Missile Wing, Minot AFB, Minot, North Dakota
  • 740th Missile Squadron
  • 741st Missile Squadron
  • 742d Missile Squadron
• 341st Missile Wing, Malmstrom AFB, Montana
  • 10th Missile Squadron
  • 12th Missile Squadron
  • 490th Missile Squadron
• 625th Strategic Operations Squadron – Offutt AFB, Nebraska

History

The Twentieth Air Force was brought into existence on 4 April 1944 specifically to perform strategic bombardment missions against Japan. This was done at the insistence of General Henry H. (Hap) Arnold, commander of the USAAF, mainly to avoid having the new B-29 Superfortress being diverted to tactical missions under pressure from the China Burma India Theater commanders. Twentieth Air Force was to be commanded by General Arnold himself at Joint Chiefs of Staff level. Twentieth Air Force was completely autonomous and its B-29s were to be completely independent of other command structures and would be dedicated exclusively against strategic targets in Japan.

In addition Twentieth Air Force was chosen (secretly) to be the operational component of the Manhattan Project in 1944, and performed the atomic attacks on Japan in August 1945.

Initially under the command of General Hap Arnold, and later General Curtis LeMay and General Nathan Twining, in August 1945 the Twentieth Air Force was placed under the U.S. Strategic Air Forces in the Pacific which was commanded by General Carl Spaatz.

World War II operations

Operation Matterhorn

Main article: Operation Matterhorn

Boeing B-29A-70-BN (S/N 44-62305) of the 6th Bombardment Group. Note the streamlined top turret added on block 40 A models and later. (U.S. Air Force photo)

58th Bomb Wing B-29s at a deployed base in India, 1944

Fuel dump at a forward airfield in China, 1944

Kumming Air Base, China, 1944

B-29s of the 58th Bomb Wing on a mission to Rangood, Burma, 1944

Operation Matterhorn was the name for the B-29 Superfortress offensive against the Empire of Japan from airfields in China. On 10 April 1944, the Joint Chiefs of Staff (JCS) informally approved Operation Matterhorn. The operational vehicle was to be the 58th Bombardment Wing (Very Heavy) of the XX Bomber Command.

However, in early 1944, the B-29 was not yet operationally ready. The aircraft had been in development at Boeing since the late 1930s and the first XB-29 (41-0002) flew on 21 September 1942. However, the aircraft suffered from an overwhelming number of development issues, and with engine problems (fires). As a result most of the first production B-29s were still held up at the Air Technical Service Command (ATSC) modification centers, awaiting modifications and conversion to full combat readiness. By March 1944, the B-29 modification program had fallen into complete chaos, with absolutely no bombers being considered as combat ready. The program was seriously hampered by the need to work in the open air in inclement weather, as many hangars were simply too small to house the aircraft indoors; by delays in acquiring the necessary tools and support equipment, and by the USAAF's general lack of experience with the B-29.

General Arnold became alarmed at the situation and directed that his assistant, Major General B. E. Meyer, personally take charge of the entire modification program. The resulting burst of activity that took place between 10 March and 15 April 1944 came to be known as the "Battle of Kansas". Beginning in mid-March, technicians and specialists from the Boeing Wichita and Seattle factories were drafted into the modification centers to work around the clock to get the B-29s ready for combat. The mechanics often had to work outdoors in freezing weather. As a result of superhuman efforts on the part of all concerned, 150 B-29s had been handed over to the XX Bomber Command by 15 April 1944.

The headquarters of the XX Bomber Command had been established at Kharagpur India on 28 March 1944. The commander was General Kenneth B. Wolfe. The first B-29 reached its base in India on 2 April 1944. In India, existing airfields at Kharagpur, Chakulia, Piardoba and Dudkhundi had been converted for B-29 use. All of these bases were located in southern Bengal and were not far from port facilities at Calcutta. All of these bases had originally been established in 1942–43 for B-24 Liberators. The conditions at these bases were poor, and the runways were still in the process of being lengthened when the first B-29s arrived.

The Headquarters of the 58th Bomb Wing, together with the four squadrons of the 40th Bombardment Group (the 25th 44th, 45th, and 395th) were assigned to the airfield at Chakulia, the first planes arriving there on 2 April 1944. The Headquarters was moved to Kharagpur on 23 April. The 444th Bombardment Group (676th, 677th, 678th and 679th Squadrons) went to Charra, arriving there on 11 April. The 462d Bombardment Group (768th, 769th, 770th, and 771st squadrons) to Piardoba, arriving there on 7 April. The 468th Bombardment Group (792nd, 793rd, 794th and 795th Squadrons) arrived at Kharagpur on 13 April. The 444th Bombardment Group later moved to a permanent base at Dudhkundi, leaving Charra to become a transport base for the C-87s and C-46s which would support the effort.

The B-29s had arrived in the China Burma India Theater, but not without incident. After five B-29s crashed near Karachi due to overheated engines, the entire fleet was grounded. The problem was traced to high ground temperatures in India that exceeded the engines’ normal operating limits. Further modifications were made to the engine cooling baffles, oil lubrication tubes and cowl flaps, but those changes only lessened the difficulties rather than solving the problem. The forward bases in China were declared usable even if conditions there were far less than ideal. By 8 May 1944, 130 B-29s had reached their bases in India. The B-29 Superfortress, ready or not, was about to go to war.

The first B-29 bombing raid from India took place on 5 June 1944. Ninety-eight B-29s took off from bases in eastern India to attack the Makasan railroad yards at Bangkok, Thailand. This involved a 2,261-mile (3,639 km) round trip, the longest bombing mission yet attempted during the war. The engines of the B-29 were causing problems, and fourteen B-29s were forced to abort because of engine failures. The target was obscured by bad weather, necessitating bombing by radar. The formations became confused and dropped their bombs at altitudes between 17–27,000 feet rather than the planned 22–25,000 feet. Only eighteen bombs landed in the target area. Five B-29 crashed upon landing after the mission and 42 were forced to divert to other airfields because of a shortage of fuel. The B-29 campaign was off to a bad start, although none of the bombers was actually lost to enemy action.

Bombardment operations against Japan were planned to be carried out from bases in China. There were four sites in the Chengtu area of China that were assigned to the B-29 operation—at Kwanghan, Kuinglai, Hsinching, and Pengshan. Construction work at these bases had begun as early as November 1943, but progress had been slow since much of the work had be done by hand. However, by May enough progress had been made that the four bases could actually be used, but the conditions were far from ideal.

The primary flaw in the Operation Matterhorn plan was the fact that all the supplies of fuel, bombs, and spares needed to support the forward bases in China had to be flown in from India over the Hump, since Japanese control of the seas around the Chinese coast made seaborne supply of China impossible. Many of the supplies had to be delivered to China by the B-29s themselves. For this role, they were stripped of nearly all combat equipment and used as flying tankers and each carried seven tons of fuel. The Hump route was so dangerous and difficult that each time a B-29 flew from India to China it was counted as a combat mission. The first action by the B-29 took place on 26 April 1944. Major Charles Hansen was flying a load of fuel to China when his plane was attacked by six Japanese Nakajima Ki-43 Hayabusa fighters. The attack was beaten off, but one crew member was injured.

On 6 June General Wolfe received an urgent message from Washington complaining that the JCS were getting impatient and that they wanted an immediate attack on Japan proper. This attack was needed to relieve pressure from Japanese forces in eastern China where Fourteenth Air Force airfields were under attack and to assist an "important operation" in the Pacific which was later revealed to be the Battle of Saipan.

General Wolfe was caught flatfooted by this order and attempted to delay the mission until late June when he would have a larger force and more supplies in place at the forward bases in China. However, Washington demanded that he put a minimum of 70 B-29's over Japan by 15 June. One of the problems was that only 86 B-29's could be equipped with the bomb-bay tanks needed for the long flight to Japan, and, based upon previous experience, more than 20 of them would probably fail to leave their bases in China because of engine fires or other mechanical problems, while others would encounter problems along the way and never reach the target. But when your superiors give the orders, you do as you are told.

By mid-June, enough supplies had been stockpiled at Chinese forward bases to permit the launching of a single attack against targets in Japan. It was a nighttime raid to be carried out on the night of 14/15 June 1944 against the Imperial Iron and Steel Works at Yawata on Kyūshū. Staging at the forward bases in China began on 13 June 1944 and was completed shortly before H-hour on 15 June. The B-29's had left India fully loaded with bombs, requiring only refueling at the forward bases in China. Each plane carried two tons of 500-pound General Purpose bombs, considered powerful enough to disrupt the fragile coke ovens by either a direct hit or by blast. Of the 92 aircraft leaving India, only 79 had actually reached China, with one plane crashing enroute. Unfortunately, the Japanese had been warned of the approaching raid and the city of Yawata was blacked out and haze and/or smoke helped to obscure the target. Only 15 aircraft bombed visually while 32 bombed by radar. Only one bomb actually hit anywhere near the intended target, and the steel industry was essentially untouched. One B-29 was lost to enemy fire and six were lost in various accidents.

Although very little damage was actually done, the Yawata raid was hailed as a great victory in the American press, since it was the first time since the Doolittle raid of 1942 that American aircraft had hit the Japanese home islands.

General Wolfe was ordered to keep up the attacks even in spite of a shortage of fuel and bombs at the Chengtu bases. On 7 July, eighteen B-29s attacked targets at Sasebo, Nagasaki, Omura, and Yawata with ineffective results. On 9 July, seventy-two B-29s hit a steel-making complex at Anshan in Manchuria. Of the 72 aircraft launched against Anshan, one crashed on takeoff and eleven suffered mechanical failures en route to Manchuria and had to abort. Four aircraft were lost and results were poor.

On the night 10–11 August, 56 B-29s staged through British air bases in Ceylon attacked the Plajdoe oil storage facilities at Palembang on Sumatra in Indonesia. This involved a 4030-mile, 19 hour mission from Ceylon to Sumatra, the longest American air raid of the war. Other B-29s laid mines in the Moesi River. At the same time, a third batch of B-29s attacked targets in Nagasaki. These raids all showed a lack of operational control and inadequate combat techniques, drifting from target to target without a central plan and were largely ineffective.

In Washington, it was decided that new leadership was needed for Twentieth Air Force. General Wolfe's replacement was Major General Curtis E. LeMay, who arrived in India on 29 August He had earned a good reputation as commander of a B-17 Flying Fortress air division in Europe. He was known as a tough, Patton-type of commander and had a "take-charge" reputation. As a start, he stepped up the frequency of B-29 missions and intensified the training of combat crews. He replaced the four-plane diamond formation with one of twelve aircraft grouped in a defensive box. He introduced the concept of lead crews who would be responsible for finding and marking the target. In the future, both the bombardier and radar operator would control the bombing run, so that whoever had sight of the target at the critical moment in the bomb run could release the bombs.

It took a while for these changes to have an effect. Another raid against Anshan in Manchuria on 26 September was inconclusive. An attack on 25 October on the Omura aircraft factory on Kyūshū showed better results, particularly in the decision to use a two-to-one mixture of high-explosive and incendiary bombs. A raid was carried out on 11 November against the Chinese city of Nanking, which had been occupied by the Japanese since 1937.

Supply problems and aircraft accidents were still preventing a fully effective concentration of force and effort. In addition, Japanese defensive efforts were becoming more effective. On 21 November six B-29s were destroyed by Japanese aircraft during a raid on Omura. A similar loss rate occurred on 7 December over the Manchurian Aircraft Company plant at Mukden. B-29 losses to accidents, enemy interception, and to Japanese air attacks on the Chengdu forward bases soon came to be prohibitive, and by the end of 1944 had reached 147.

By late 1944, it was becoming apparent that B-29 operations against Japan staged out of bases in China and India were far too expensive in men and materials and would have to be stopped. In December 1944, the Joint Chiefs of Staff made the decision that Operation Matterhorn would be phased out, and the 58th Bombardment Wing's B-29s would be moved to newly-captured bases in the Marianas in the central Pacific.

The last raid out of China was flown on 15 January 1945, which was an attack on targets in Formosa (Taiwan). The 58th Bombardment Wing then redeployed to new bases in the Marianas in February.

In retrospect, Operation Matterhorn had been a failure. The supply problems proved to be insoluble, and the bases in China were too far west, requiring long overflights of Japanese-occupied territory in China before the Japanese home islands could be reached. Even then, only the southernmost Japanese island of Kyūshū was in range of the B-29s. Nevertheless, the Matterhorn operation provided valuable experience for the B-29 operations that were to be mounted from the far more convenient bases in the Marianas.

Attacks on Japan from the Marianas

Oblique airphoto of North Field, Tinian Island, 1945. Note the massive runway system and number of hardstands, each hardstand where a B-29 was parked and maintained.

Twentieth Bomb Wing B-29s flying near Mount Fuji, Japan, 1945

B-29s on an incendiary bomb drop over Japan, 1945

Photo of the firebombing of Tokyo, 26 May 1945.

First B-29 to land on Iwo Jima, 4 March 1945.

315th Bomb Wing Bell-Atlanta B-29B-60-BA Superfortress "Pacusan Dreamboat" (44-84061), designed for fast hit-and-run raids, 1945.

The Marianas chain of islands, consisting primarily of Saipan, Tinian, and Guam, were considered as being ideal bases from which to launch B-29 operations against Japan. The islands were about 1,500 miles (2,400 km) 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.

First to be attacked was Saipan. On 11 June a four-day naval and air bombardment of the island began. On the 15th, Marine units stormed ashore, followed a day later by Army units. After several weeks of heavy fighting, during which over 3000 American and 24,000 Japanese lives were lost, 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 20 and 23 July respectively. These islands were declared secure on 9 August. The US now had its bases. Construction of the B-29 airfields on Saipan began almost immediately, even while the fighting was still going on.

The XXI Bombardment Command had been assigned the overall responsibility of the B-29 operations out of the Marianas bases. The XXI BC had been activated at Smokey Hill AAF, Kansas on 1 March 1944. The field on Saipan was to be occupied by the 73rd Bombardment Wing (which consisted of the 497th, 498th, 499th, and 500th Bombardment Groups). The 73rd BW has been formed at Walker AAF, Kansas on 12 August 1943.

The first B-29 arrived on Saipan on 12 October 1944. It was piloted by General Hansell himself. By 22 November, over 100 B-29s were on Saipan. The XXI Bomber Command was assigned the task 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, eighteen B-29s attacked Japanese installations on Truk. Four Superfortresses had to abort because of the usual engine problems, and combat formations were scrappy. Truk was hit again by B-29s on 30 October and 2 November.

Aware that there was now a new threat, Japanese aircraft based on Iwo Jima staged a low-level raid on Saipan on 2 November, damaging several B-29s on the ground. Retaliatory strikes were ordered on Iwo Jima on 5 and 11 November, but the results were poor. Occasional Japanese air attacks on the Mariana Islands continued until January 1945 and resulted in the destruction of 11 B-29s and damage to another 43.

General Arnold was pressing for an attack on Japan from the new airfield on Saipan as soon as possible. The first raid against Japan took place on 24 November 1944. The target was the Nakajima Aircraft Company's Musashi engine plant just outside Tokyo. 111 B-29s took off, Seventeen of them had to abort due to the usual spate of engine failures. The remainder approached the target at altitudes of 27–32,000 feet. 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 200 mph at precisely the altitudes at which the bombers were operating. This caused the bomber formations to be disrupted and made accurate bombing impossible. In addition, the Nakajima plant was covered in patchy cloud at the time and only 24 of the B-29s dropped their bombs in even roughly the right place. The target was hardly damaged, and one B-29 was rammed by a Japanese fighter and destroyed.

After several more disappointing raids on Japan from Saipan, it appeared that the Marianas operation was going the way of Operation Matterhorn, with losses being high and not much damage to the enemy being done. Since little progress was being made, General Arnold recalled General Hansell and moved General LeMay from India to take over the XXI BC. LeMay arrived in the Marianas on 20 January 1945.

Concerned about the relative failure of the B-29 offensive to deal any crippling blows to Japan, General LeMay issued a new directive on 19 February. General LeMay had analyzed the structure of the Japanese economy, which depended heavily on cottage industries housed in cities close to major industrial areas. By destroying these feeder industries, the flow of vital components to the central plants could be slowed, disorganizing production of weapons vital to Japan. He 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 assembly over the base at the start of the mission or along the way would be needed. Consequently, aircraft could go directly from the base to the target and return, maximizing the bomb load and saving substantially on fuel. He ordered that all the B-29s be stripped of their General Electric defensive gun systems, leaving only the tail gun. The weight of extra crew members, armament, and ammunition would go into bombs, each B-29 being loaded down with six to eight tons of M69 incendiary bombs. These bombs would be dropped from altitudes of only 5 to 6 thousand feet with the M69 containing napalm packed in cheesecloth bags, and ejected them after landing so that small packets of flaming napalm burst against potential targets. This strategy would enable the B-29s to escape the effects of the jet stream and would get the bombers below most of the cloud cover. In addition, the B-29s would no longer have to struggle up to 30,000 feet (9,100 m) and this would save on fuel and on wear and tear to the engines. It was believed that Japanese night fighter forces were relatively weak, but flak losses were expected to be substantial.

The first raid to use these new techniques was on the night of 9–10 March against Tokyo. Another wing—the 314th Bombardment Wing (19th, 29th, 39th, and 330th BG) commanded by Brig. Gen. Thomas S. Power--had arrived in the Marianas and was stationed at North Field on Guam. A total of 302 B-29s participated in the raid, with 279 arriving over the target. The raid was led by special pathfinder crews who marked central aiming points. It lasted for two hours. The raid was a success beyond General LeMay's wildest expectations. The individual fires caused by the bombs joined to create a general conflagration known as a firestorm. When it was over, sixteen square miles of the center of Tokyo had gone up in flames and nearly 84,000 people had been killed. Fourteen B-29s were lost. The B-29 was finally beginning to have an effect.

On the night of 11–12 March, the B-29s were in action again, this time against the city of Nagoya. This time, the scattered fires did not join to create a general firestorm, and only two square miles of the city were destroyed. On the night of 13 March–14, eight square miles of Osaka went up in flames. On 16–17 March, three square miles of Kobe were destroyed, and on 19–20 March in a return visit to Nagoya, three more square miles were destroyed. This destructive week had killed over 120,000 Japanese civilians at the cost of only 20 B-29s lost. The strategic bombing campaign had at last been justified.

In April 1945, General LeMay gave new orders for more incendiary raids. This time, aircraft engine factories at Musashi and Nagoya were to be hit, but urban areas in Tokyo, Nagoya, Osaka, Kawasaki, Kobe, and Yokohama were also to be attacked. On 7 April 153 B-29s struck the aircraft-engine complex at Nagoya, destroying about 90 percent of that facility. Five days later, 93 B-29s destroyed the Nakajima factory at Musashi. The Japanese aircraft engine industry essentially ceased to exist after this time.

On 13 April 327 B-29s burned out eleven more square miles of Tokyo. Seven more B-29s were lost.

On 5 June, the B-29s attacked Kobe with such effectiveness that the city was crossed off the target list as not worth revisiting. By the end of the month, the six major cities on LeMay's list had all been effectively destroyed.

The newly-arrived 315th Bombardment Wing (16th, 331st, 510st, and 502nd BGs) stationed at Northwest Field on Guam was equipped entirely with the B-29B variant. This variant had been built by Bell Aircraft at Marietta, Georgia and had been manufactured without the General Electric gun system in order to save weight. The 315th had been trained for low-altitude, nighttime pathfinder missions. Between 26 June and 10 August, they carried out a series of strikes against oil production facilities which essentially shut down the Japanese oil industry.

By mid-June, most of the larger Japanese cities had been gutted, and LeMay ordered new incendiary raids against 58 smaller Japanese cities. By now, the B-29 raids were essentially unopposed by Japanese fighters. In late June, B-29 crews felt sufficiently confident that they began to drop leaflets warning the population of forthcoming attacks, followed three days later by a raid in which the specified urban area was devastated.

In June 1945, the XX and XXI Bombardment Commands were grouped under the U.S. Strategic Air Forces in the Pacific, under the command of General Carl A. Spaatz.

By the end of June, the civilian population began to show signs of panic, and the Imperial Cabinet first began to consider negotiating an end to the war. However, at that time, the Japanese military was adamant about continuing on to the bitter end.

The atomic bomb

See also: Atomic bombings of Hiroshima and Nagasaki

Colonel Paul Tibbets waving from Enola Gay's cockpit before taking off for the bombing of Hiroshima

The mushroom cloud over Hiroshima after the dropping of Little Boy

Crew of Bockscar, C-15. front row: Dehart, Kuharek, Buckley, Gallagher, Spizer; back row: Olivi, Beahan, Sweeney, Van Pelt, Albury

Bockscar nose art. The "fat man" silhouettes represent four pumpkin bomb missions (black) and the atomic bomb drop on Nagasaki (a red symbol, fourth in the line of five symbols).

The Twentieth Air Force's 509th Composite Group is perhaps best remembered today as the unit which delivered the atomic bombs which destroyed the Japanese cities of Hiroshima and Nagasaki, bringing the war in the Pacific to an end.

A special crew training program had been initiated under the command of Colonel Paul W. Tibbets, Jr. Col. Tibbets was a veteran of B-17 Flying Fortress operations in Europe and North Africa and had been involved in B-29 flight test operations. In September 1944, Colonel Tibbets took over the command of the newly-activated 509th Composite Group at Wendover AAF, an air base near in Utah. It had only one Bombardment Squadron—the 393rd commanded by Major Charles W. Sweeney. The 509th Composite Group was a completely self-sufficient unit, with its own engineer, material, and troop squadrons as well as its own military police unit. Since the Manhattan project was carried out in an atmosphere of high secrecy, the vast majority of the officers and men of the 509th Composite Group were completely ignorant of its intended mission.

The 509th Composite Group was deployed overseas in the spring of 1945. The 509th was formally a part of XXI Bombardment Command based in the Marianas. By July, the bombers were established at North Field on Tinian, which had just been completed for the 313th Bombardment Wing.

President Harry S. Truman was fully aware of the projections of appalling American casualties should it be necessary to invade Japan (a half-million casualties were estimated), and had no hesitation in authorizing the use of the new weapon in getting the Japanese to surrender. On 24 July, a directive was sent to General Carl A. Spaatz ordering the 509th to deliver its first atomic bomb as soon as weather would permit. The cities of Hiroshima, Kokura, Niigata and Nagasaki were potential targets. Truman gave his final go-ahead from Potsdam on 31 July.

The attack began with a flight of three special reconnaissance F-13As (RB-29s) which took off to report the weather over the primary and secondary targets. Col. Tibbets followed in his B-29 aircraft, Enola Gay an hour later, accompanied by two other B-29s which would observe the drop. While on the way to Japan, Major Claude Eatherly, flying Straight Flush, radioed that Hiroshima was clear for a visual bomb drop. Navy weapons expert Captain William Parsons armed the bomb while in flight, as it was deemed too dangerous to do this on the ground at North Field, lest an accident happen and the bomb go off, wiping out the entire base.

At 8:15 am, the Enola Gay released Little Boy from an altitude of 31,500 feet (9,600 m). The radar fuse on the bomb had been preset to go off at an altitude of 2,000 feet (610 m) above the ground. In the ensuing explosion, yielding about 12 kilotons of TNT in explosive power, about 75,000 people were killed and 48,000 buildings were destroyed.

President Truman announced via radio the dropping of the atomic bomb to the United States and allies. At first, the Japanese did not know exactly what had happened, and poor communications between Tokyo and the devastated Hiroshima did not help. Even in spite of the bomb, there were still some Japanese officers who wanted the war to continue on to the bitter end. On 8 August Foreign Minister Shigenori Tōgō informed Emperor Hirohito that total destruction awaited Japan if it did not accept the terms of the Potsdam Declaration and surrender. The Emperor agreed with this gloomy assessment, and Togo dispatched the Emperor's message to the Prime Minister, Baron Kantarō Suzuki, who was unable to convene the Supreme War council until the next day.

While the Japanese government was debating its options, there was no let-up with the conventional B-29 raids. B-29s from the 58th, 73rd, and 313th BWs hit the Toyokawa Arsenal the next day. On the night of 7 August, the 525th BG dropped 189 tons of mines on several different sea targets. On 8 August, the 58th, 73rd, and 313th BWs dropped incendiary bombs on targets at Yawata in the southern island of Kyūshū. At the same time, the 314th BW hit an industrial area of Tokyo. The Japanese defenses were still effective enough to down four B-29s during the Yawata raid and three at Tokyo.

In the meantime, since there was still no official reaction from Japan, the Americans felt that there was no alternative but to prepare a second atomic attack. The plutonium bomb called "Fat Man" was loaded into a B-29 known as Bockscar (Martin-Omaha built B-29-35-MO serial number 44-27297, the name often spelled Bock's Car), named after its usual commander, Captain Frederick C. Bock. However, on this mission, the aircraft was flown by Major Sweeney, with Capt. Bock flying one of the observation planes. The primary target was to be the Kokura Arsenal, with the seaport city of Nagasaki as the alternative.

Bockscar took off on 9 August, with Fat Man on board. This time, the primary target of Kokura was obscured by dense smoke left over from the earlier B-29 raid on nearby Yawata, and the bombardier could not pinpoint the specified aiming point despite three separate runs. So Sweeney turned to the secondary target, Nagasaki. There were clouds over Nagasaki as well, and a couple of runs over the target had to be made before the bombardier could find an opening in the clouds. At 11:00 am, Fat Man was released from the aircraft and after a long descent, the bomb exploded. The yield was estimated at 22 kilotons of TNT. Approximately 35,000 people died at Nagasaki from the immediate blast and fire.

After releasing the bomb, Sweeney was forced to divert to Okinawa because of a problem with a fuel transfer pump, and because of the long flight with multiple bomb runs and circling for better weather. There was not even enough fuel left to fly to Iwo Jima. After refueling on Okinawa, the B-29 returned to Tinian.

That very same day, the Soviet Union had declared war on Japan, and it launched an immediate large armored invasion of Manchuria. The Emperor ordered that the government accept the Allied terms of surrender at once. It took time for the full details to be worked out, and there was a very real danger that some elements of the Japanese military would still not accept surrender, and might attempt a military coup d'état, even against their Emperor. In the meantime, conventional bombing of Japanese targets still continued, with a record number of 804 B-29s hitting targets in Japan on 14 August. On the morning of 15 August, the Emperor broadcast by radio his command of Japan's surrender in an address to his nation. Practically none of his subjects had never heard his voice before.

All further offensive operations against Japan ceased after the Emperor's broadcast. After that time, most of the B-29s in the Pacific were diverted to missions of mercy, dropping food and clothing to thousands of Allied prisoners of war held in Japan, China, Manchuria, and Korea. 1066 B-29s participated in 900 missions to 154 camps. Some 63,500 prisoners were provided with 4470 tons of supplies. These flights cost eight B-29s lost by accidents, with 77 crew members aboard.

The Japanese surrender was formally signed on 2 September 1945, aboard the huge battleship USS Missouri in Tokyo Bay, bringing the Pacific War to an end.

Postwar era/Korean War

Following the end of World War II, Twentieth Air Force remained in the Pacific, being headquartered on Guam. The vast majority of its fleet of B-29 Superfortreses were returned to the United States as part of "Operation Sunset" by mid-June 1946. In June 1945, the Twentieth Air Force was reassigned and placed under the United States Far East Air Forces.

In March 1946, USAAF Chief General Carl Spaatz had undertaken a major re-organization of the postwar USAAF that had included the establishment of Major Commands (MAJCOM), who would report directly to HQ United States Army Air Forces. In the United States, three MAJCOMs were established: Strategic Air Command (SAC), to provide a long-range striking force capable of bombardment operations in any part of the world; Air Defense Command (ADC), to defend the United States against attack from the air; and Tactical Air Command (TAC), to support the operations of ground forces. With this reorganization, the Atomic Bomb mission of Twentieth Air Force was reassigned to SAC.

The new postwar mission of Twentieth Air Force became the defense of the Ryukyu Islands and was reassigned to Kadena AB, Okinawa. It commanded the following units:

• Naha Air Base, Okinawa
  51st Fighter-Interceptor Wing/Group (F-80, F-82)
• Kadena Air Base, Okinawa
  31st Photo Reconnaissance Squadron, (RB-29)
• Anderson Air Force Base, Guam
  19th Bombardment Wing/Group (B-29)

On 27 June, the United Nations Security Council voted to assist the South Koreans in resisting the invasion of their nation by North Korea. President Harry S. Truman authorized General Douglas MacArthur (commander of the US occupying forces in Japan) to commit units to the battle. MacArthur ordered General George E. Stratemeyer, CIC of the Far Eastern Air Force (FEAF) to attack attacking North Korean forces between the front lines and the 38th parallel. At that time, the 22 B-29s of the 19th Bombardment Group stationed at Andersen Field on Guam were the only aircraft capable of hitting the Korean peninsula, and this unit was ordered to move to Kadena air base on Okinawa and begin attacks on North Korea. These raids began on 28 June. On 29 June, clearance was given for B-29 attacks on airfields in North Korea. The B-29s were frequently diverted into tactical attacks against advancing North Korean troops.

On 8 July, a special FEAF Bomber Command was set up under the command of Major General Emmett O'Donnell. On 13 July, the FEAF Bomber Command took over command of the 19th Bombardment Group and of the 22nd and 92nd Bombardment Groups which had been transferred from SAC bases in the United States.

The other major components of Twentieth Air Force, the 51st Fighter-Interceptor Wing was reassigned to Fifth Air Force at Itazuke AB, Japan in September 1950, where its F-82 Twin Mustangs and F-80 Shooting Stars were used in combat over Korea. The very long-range RB-29s of the 31st Strategic Reconnaissance Squadron (unarmed B-29s fitted with additional internal fuel tanks within the bomb bays and various photo mapping cameras) were also reassigned to Fifth Air Force at Johnson AB, Japan where they were combined with other aerial reconnaissance units.

With the end of its combat role in Korea and its operational units reassigned, the command was concerned primarily with logistic support for the operations of other organizations although a few combat aircraft were retained for air defense. It was inactivated on 1 March 1955.

Post Cold War history

Minuteman missile combat crew in 2006.

Since 1991, the Twentieth Air Force is operationally responsible for all land-based inter-continental ballistic missiles. Today 450 Minuteman III missiles remain on alert. The current commander is Major General C. Donald Alston [1]. On 1 December 2009, the Twentieth Air Force was transferred to the new Air Force Global Strike Command.

Campaigns and Decorations

• Campaigns. World War II: American Theater; Asiatic-Pacific Theater; Korea: Korean Service.

• Decorations. Air Force Outstanding Unit Awards: 1 Sep 1991-31 Aug 1993; 1 Sep 1993-14 Oct 1994; 1 Oct 1995-30 Sep 1997; 1 Oct 1997-30 Sep 1999; 1 Oct 1999-30 Sep 2001; 1 Oct 2001-30 Sep 2003; 1 Oct 2005-30 Sep 2007.

Lineage

• Established as Twentieth Air Force and activated on 4 Apr 1944

Inactivated on 1 Mar 1955

• Activated on 1 Sep 1991.

Re-designated as: Twentieth Air Force (Air Forces Strategic) on 1 Dec 2009.

Assignments

• United States Army Air Forces, 4 April 1944

Attached to United States Strategic Air Forces in the Pacific

• Pacific Air Command, U.S. Army, (later Far East Air Forces), 6 December 1945 – 1 March 1955
• Strategic Air Command, 29 March 1991
• Air Combat Command, 1 June 1992
• Air Force Space Command, 1 July 1993
• Air Force Global Strike Command, 7 August 2009

Components

Commands

• VII Fighter Command, 5 Aug 1945-c. Aug 1946
• XX Bomber Command, 19 Apr 1944-18 Jul 1945
• XXI Bomber Command, 9 Nov 1944-18 Jul 1945

Bombardment Wings

• 19th Bombardment Wing, 17 Aug 1948-16 May 1949, 17 Oct 1949-11 Jun 1954

Detached 1 Jun 1953-c. 28 May 1954

• 58th Bombardment Wing, 29 Jun-12 Oct 1944; 1 Feb-15 Nov 1945
• 73d Bombardment Wing, c. 6 Aug-9 Nov 1944
• 98th Bombardment Wing (Attached 18 Jun-25 Jul 1954)
• 307th Bombardment Wing (Attached 18 Jun-19 Nov 1954)
• 313th Bombardment Wing, 16 Jul 1945-13 Mar 1946
• 314th Bombardment Wing, 16 Jul 1945-15 May 1946
• 315th Bombardment Wing, 16 Jul 1945-30 May 1946

Fighter Wings

• 18th Fighter-Bomber Wing, 10 Nov 1954-31 Jan 1955
• 23d Fighter Wing, 16 Aug 1948-25 Apr 1949
• 51st Fighter Wing, 16 May 1949-1 Mar 1955

Detached 25 Sep-12 Oct 1950

• 301st Fighter Wing, 21 May 1945-14 Aug 1945

Detached 21 May 1945-14 Aug 1945

Missile Wings

• 44th Missile Wing, 1 Sep 1991-5 Jul 1994
• 90th Missile (later, 90th Space) Wing, 1 Sep 1991-Present
• 91st Missile (later, 91st Missile Group; 91st Missile Wing; 91st Space Wing, 91st Missile Wing); 1 Sep 1991-Present
• 321st Missile Wing (later, 321st Missile Group), 1 Sep 1991-2 Jul 1998
• 341st Missile (later, 341st Space) Wing, 1 Sep 1991-Present
• 351st Missile Wing, 1 Sep 1991-31 Jul 1995

Other Wings

• 310th Training and Test Wing 1 Sep 1991-1 Jul 1993
• 374th Troop Carrier Wing, (Attached 17 Aug 1948-5 Mar 1949).

Stations

• Washington, D.C., 4 April 1944
• Harmon Field, Guam, Mariana Islands, July 1945
• Kadena AB, Okinawa, 16 May 1949 – 1 March 1955
• Vandenberg Air Force Base, California, 1 September 1991 – 1993
• FE Warren Air Force Base, Wyoming, 1993 – present

See also

• Pacific War
• Timeline WW II – Pacific Theatre
• South-East Asian Theatre of World War II
• United States Strategic Command
• Bombing of Tokyo in World War II
• United States strategic bombing of Japan
• Bombing of Kobe in World War II
• fire-bombing

References

 This article incorporates public domain material from the Air Force Historical Research Agency

• This article incorporates text from this source, which is in the public domain: 20th Air Force Website

Bibliography

• Birdsall, Steve. Saga of the Superfortress: The Dramatic Story of the B-29 and the twentieth Air Force. London: Sidgwick & Jackson, 1981. ISBN 0-283-98786-3.
• Dorr, Robert F. B-29 Superfortress Units of the Korean War. Botley, Oxford, UK: Osprey Publishing, 2003. ISBN 1-84176-654-2.
• Dorr, Robert F. B-29 Units of World War II. Botley, Oxford, UK: Osprey Publishing, 2002. ISBN 1-84176-285-7.
• Freeman, Roger A. Boeing B-29 Superfortress U.S.A.A.F. 1942–1945 (Camouflage & Markings No. 19). London: Ducimus Books, 1970.
• Marshall, Chester. Warbird History: B-29 Superfortress. Osceola, Wisconsin: Motorbooks International, 1993. ISBN 0-87938-785-8.
• Maurer, Maurer. Air Force Combat Units Of World War II. Maxwell Air Force Base, Alabama: Office of Air Force History, 1983. ISBN 0-89201-092-4.
• Rhodes, Richard. The Making of the Atomic Bomb. Simon and Schuster, 1986. ISBN 0-68481-378-5.
• Rust, Kenn C. Twentieth Air Force Story...in World War II. Temple City, California: Historical Aviation Album, 1979. ISBN 0-911852-85-9.

External links

• Twentieth Air Force Factsheet

• AIR FORCE MAGAZINE, Journal of the Air Force Assoc., August 2008.
• US ARMY History: Control of Army Air Operations Overseas in Washington Command Post:The Operations Division. United States Army Center of Military History. CMH Pub 1-2.
• US ARMY History: QUADRANT Conference
• HistoryNET: Operation Matterhorn
• USAAF: Operation Matterhorn