The USAAF was interested in its own independence once the War was over and so concentrated its efforts on strategic bombing as the justification for such. I cannot find a reference to this at hand, but it has been recorded (by Kenney) that when the CCS ordered the creation of an independent Strategic Air Force in the Pacific in the build-up for DOWNFALL, MacArthur called Kenney and protested, as MacArthur was REALLY dedicated to consolidated command. MacArthur asked Kenney to protest the intrusion of this into the new Far East Command structure, and Kenney just laughed and told MacArthur that, if he (Kenney) protested, MacArthur would be dealing with a new Air Commander the next day, as he would be fired. Kenney ensured that MacArthur had priority of targets under his control for DOWNFALL but that was as far as Arnold would go.
The reason that the United States Army Strategic Air Forces, Pacific was established is that there would be two very long range bomber air forces and a headquarters to coordinate them was necessary. This goes back to the British arrangement in WWII. The British had established a Chiefs of Staff Committee which directed RAF Bomber Command's campaign against German industries. When the USAAF Eighth Air Force came to England in 1942, it fitted very well into this system. This arrangement was formally recognized after the issuance of the Casablanca directive on 21 Jan 1943 which put the Combined Bomber Offensive (CBO) under direct control of the Combined Chiefs of Staff (CCS).
This arrangement worked well in Europe because the theater was an Army theater with only two players. The Pacific was another story.
There were three theater commanders in the Pacific, Stillwell, Nimitz and Macarthur, and none of them had shown himself to be an enthusiastic advocate of the mission for which the B-29 had been designed and built and the USAAF was reluctant to give these commanders control of it. The British also wanted the CCS to have a say because the B-29s would be based in India initially but General Arnold maintained that the B-29 would be strictly an American affair and control of the B-29s should be under the Joint Chiefs of Staff (JCS). After discussion with the British, they agreed that there would be no CCS control
The Joint Planning Staff (JPS) began work on a paper defining the task and command structure of the B-29 bomber offensive. After much discussion and draft papers, the JPS sent a paper to the Joint Strategic Survey Committee which forwarded it to the JCS on 18 Mar 1944. Admiral William D. Leahy, Chairman of the JCS, recommended its approval but General Arnold offered as an alternative certain proposals made by Admiral Ernest King, Chief of Naval Operations and the Navy representative on the JCS, calling for the creation of "an air force, known as the Joint Chiefs of Staff Air Force, to be commanded by the Commanding General, Army Air Forces, who will be the executive agent of the Joint Chiefs of Staff." As a result, the plan was approved and Arnold would command the force, acting under specific directives which he, as a member of the JCS, would help to frame.
The new paper constituted the formal charter under which the Twentieth Air Force would operate, i.e.:
1. A strategic Army air force, designated the Twentieth, was to be established, to operate directly under the JCS with the Commanding General, AAF as executive agent to implement their directives for the employment of Very Long Range (VLR) bombers;
2. Major decisions concerning deployment, missions, and target objectives were to be made by the JCS and executed by the Commanding General, AAF;
3. Should a strategic or tactical emergency arise, theater or area commanders might utilize VLR bombers for purposes other than the primary mission, immediately informing the JCS;
4. Responsibility for providing suitable bases and base defense would rest with theater or area commanders as directed by the JCS;
5. To obviate confusion in the field, the JCS would vest theater or area commanders with logistical obligations for Twentieth Air Force units operating from their commands, with the responsibility of establishing equitable and uniform administrative policies, and with the duty of providing local coordination to avoid conflicts between theater forces operating under general directives of the JCS amid VLR forces operating under their special directives;
6. JCS directives for VLR operations would be so framed as to minimize possible friction within theaters; and
7. Arnold was to have direct communication with VLR leaders in the field, advising appropriate theater commanders of communications thus exchanged.
The B-29s would attack Japanese bases and homeland under JCS command.
Now we jump forward to summer 1945. The Twentieth Air Force is based in the Mariana Islands and has been bombing Japan for over six months. With the capture of Okinawa, the USAAF wants to establish B-29 bases there which would allow the bombers to carry larger bomb loads and hit more targets because of the shorten distance to targets. So, the Eighth Air Force is transferred without personnel and equipment to Okinawa along with its commander, Lieutenant General James H. Doolittle. When you have more than one air force in a theater, a controlling organization was always established. In the Southwest Pacific Area, there was the Far East Air Forces; in England, there was the Allied Expeditionary Air Force and the U.S. Strategic Air Forces in Europe; and in the Mediterranean, you had the Mediterranean Allied Air Force. So by moving a second B-29 outfit to the Pacific, it is logical that the U.S. Army Strategic Air Forces, Pacific, be established.
The Eighth Air Force was in the process of converting to B-29's on V-J Day. Doolittle and Spaatz were already on Okinawa, I believe. The Twentieth AF was already equipped with B-29's on Saipan and Tinian. The British Bomber Command Tiger Force was to have been equipped with Lancaster bombers bearing rather unsightly saddle tanks to extend the range, as these aircraft would have flown from the southern end of Okinawa.
The Twentieth Air Force was activated in Washington, DC on 4 Apr 1944.
The Twentieth would be assigned two subordinate units, the XX and XXI Bomber Commands.
The XX Bomber Command was activated on 20 Nov 43 at Smoky Hill AAFld, Kansas, assigned to the Second Air Force for training, and shipped out for India in the spring of 1944 after training was completed. The subordinate unit was the 58th Bombardment Wing (Very Heavy). HQ XX Bomber Command was established at Kharagpur, India on 28 Mar 44 and the command was assigned to the Twentieth Air Force in Apr 44. This unit was tasked with control of all B-29 units in India. By Mar 45, all of the tactical units of this command had moved to the Mariana Islands and in Jun 45 and reassigned to the XXI Bomber Command. The command began a movement to Okinawa arriving there on 7 Jul 45.
The XXI Bomber Command was activated on 1 Mar 44 at Smoky Hill AAFld, Kansas, assigned to the Second Air Force for training, and shipped out for the Mariana Islands in October 1944. HQ was established at Harmon Field, Guam on 2 December 1944, and was assigned to the Twentieth Air Force. This unit was tasked with control of all B-29 units in the Mariana Islands.
Everything changed on 16 July 1945. On that date:
1. The United States Army Strategic Air Forces, Pacific was activated on Guam, with General Carl Spaatz as Commanding General (Spaatz arrived on Guam on 29 July 1945). This unit was to exercise operational and administrative control of the two B-29 units in the Pacific, i.e., the Eighth and Twentieth Air Forces. This was the same system that had been used in Europe where the U.S. Strategic Air Forces in Europe exercised control over the two USAAF heavy bomber units in Europe, i.e., the Eighth and Fifteenth Air Forces. This new unit absorbed the personnel of HQ Army Air Force Pacific Ocean Area which was inactivated.
2. HQ Eighth Air Force was established on Okinawa. This unit had been transferred from High Wycombe, Buckinghamshire, England, to Okinawa without personnel and equipment. Lieutenant General James H. Doolittle assumed command on 19 July 1945.
3. The XX Bomber Command on Okinawa was inactivated and the personnel and equipment were assigned to HQ Eighth Air Force.
4. HQ Twentieth Air Force was established at Harmon Field, Guam, with Major General Curtis Emerson LeMay in command (LeMay had been commander of the XXI Bomber Command). This unit had been transferred from Washington, DC without personnel and equipment. The unit remaining in Washington was redesignated United States Army Strategic Air Forces, Pacific, Rear.
5. The XXI Bomber Command was inactivated and the personnel and equipment were assigned to HQ Twentieth Air Force.