The group later became a medium bombardment group of the Strategic Air Command, as the combat component of the 509th Bomb Wing, before being inactivated in 1952. Its lineage, honors, and history were also bestowed on the like-numbered wing in 1947.
After more than forty years of inactivation, the group was activated again as part of the 509th Bomb Wing and designated the 509th Operations Group, conducting the combat and training operations of the B-2 Spirit bomber.
| Position | Name | Dates of service |
| Group Commander | Col. Paul W. Tibbets, | December 17, 1944—January 22, 1946 |
| Deputy Group Commander | Lt.Col. Thomas J. Classen | May 4, 1945— |
| Group Operations Officer (S-3) | Major James I. Hopkins, Jr. | December 17, 1944— |
| Group Executive Officer | Lt.Col. Gerald E. Bean | December 17, 1944— |
| Group Adjutant | Captain Thomas L. Karnes | December 17, 1944— |
| Wartime Commander | Date of command |
| Major Thomas J. Classen | March 12, 1944¹ |
| Lt.Col. Paul W. Tibbets | September 14, 1944 |
| Lt.Col. Thomas J. Classen | December 17, 1944 |
| Major Charles W. Sweeney | May 4, 1945 |
| Postwar Commander | Date of command |
| Lt.Col. Virgil M. Cloyd | July 1, 1946 |
| Lt.Col. Phillip Y. Williams | June 1, 1948 |
| Lt.Col. Robert B. Irwin | September 3, 1948 |
| Lt.Col. Phillip Y. Williams | October 15, 1948 |
| Lt.Col. James I. Hopkins | January 3, 1949 |
| Lt.Col. Phillip Y. Williams | January 20, 1949 |
| Lt.Col. Jack D. Nole | May 3, 1949 |
| Lt.Col. Phillip Y. Williams | June 13, 1949 |
| Lt.Col. William S. Martensen | June 30, 1949 |
| Commander | Date of command |
| Major Hubert J. Konopacki | December 17, 1944¹ |
| Major Charles W. Sweeney | January 6, 1945 |
| Captain John J. Casey, Jr. | May 4, 1945² |
| Unit | Commander | # of personnel |
| Headquarters and Base Services Squadron | Major George W. Westcott | 99 |
| 390th Air Service Group | Lt.Col. John W. Porter | 190 |
| 1027th Air Materiel Squadron | Major Guy Geller | 140 |
| 603rd Air Engineering Squadron | Captain Earl O. Casey | 225 |
| 1395th Military Police Company | Captain Louis Schaffer | 127 |
| 1st Ordinance Squadron (Special, Aviation) | Major Charles F. Begg | 298 |
Working with the Manhattan Engineering District at Site Y in Los Alamos, New Mexico, Tibbets had selected Wendover for his training base (over Great Bend, Kansas, and Mountain Home, Idaho) because of its remoteness. On September 10, 1944, the 393rd Bomb Squadron, a unit of B-29 Superfortresses, arrived at Wendover from the 504th Bomb Group (Very Heavy) at Fairmont Army Air Base, Nebraska, where it had been in group training since March 12. When its parent group deployed to the Marianas in early November 1944, the squadron was assigned directly to the Second Air Force until creation of the 509th CG. Originally consisting of twenty-one crews, fifteen were selected to continue training and were organized into three flights of five crews, lettered A, B, and C.
The 320th Troop Carrier Squadron, the other flying unit of the 509th, came into being because of the highly secret work of the group. The organization that was to become the 509th required its own transports for the movement of both personnel and materiel, resulting in creation of an ad hoc unit nicknamed "The Green Hornet Line". Crews for this unit were acquired from the six 393rd crews not selected to continue B-29 training, some of whom chose to remain with the 509th rather than be assigned to a replacement pool of the Second Air Force. They began using Curtiss C-46 Commandos and C-47 Skytrains already at Wendover and after November 1944 flew five acquired C-54 Skymasters. The 320th TCS was formally activated at the same time as the group.
Other support units were activated at Wendover from personnel already present and working with its Project W-47 (superseded by Project Alberta) or in the 216th Base Unit, both affiliated with the Site Y project. The 390th Air Service Group was created as the command echelon for the 603rd Air Engineering Squadron, the 1027th Air Material squadron, and its own Air Base Support Squadron, but as these units became independent operationally, acted as the basic support unit for the entire 509th Group in providing quarters, rations, medical care, postal service and other basic support functions. The 603rd AES was unique in that it provided depot-level B-29 maintenance in the field, obviating the necessity of sending aircraft back to the United States for major repairs. The 603rd made a number of modifications to the first contract order of Silverplate B-29s that were later incorporated as specifications for the combat models.
The 393rd Bomb Squadron began replacement of its original B-29s with modified Silverplate airplanes with the delivery of three in mid-October 1944. These aircraft had extensive bomb bay modifications and a "weaponeer" station installed, but initial training operations identified numerous other modifications necessary to the mission, particularly in reducing the overall weight of the airplane to offset the heavy loads it would be required to carry. Five more Silverplates were delivered in November and six in December, giving the group 14 for its training operations. In January and February 1945, 10 of the 15 crews under the command of the Group S-3 (operations officer) were assigned temporary duty at Batista Field, San Antonio de los Baños, Cuba, where they trained in long-range over-water navigation.
On March 6, 1945, the 1st Ordnance Squadron (Special, Aviation) was activated at Wendover, again from Army Air Forces personnel on hand or already at Los Alamos, and concurrent with the activation of Project Alberta. Its purpose was to provide trained personnel and special equipment to the group to enable it to assemble atomic weapons at its operating base, thereby allowing the weapons to be transported more safely in their component parts. A rigorous candidate selection process was used to recruit personnel, with reportedly an 80% "washout" rate, and those made a part of the unit were not permitted transfer until the end of the war, nor were they allowed to travel without escorts from Military Intelligence units. En route to Tinian at Mather Air Force Base in California, the commanding general of the base was told at gunpoint
he was not allowed on board The Great Artiste.
With the addition of the 1st Ordnance Squadron to its roster, the 509th CG had an authorized strength of 225 officers and 1,542 enlisted men, almost all of whom deployed to Tinian. The 320th TCS did not officially deploy but kept its base of operations at Wendover. In addition to its authorized strength, the 509th had attached to it on Tinian 51 civilian and military personnel of Project Alberta, and two representatives from Washington, D.C., Brigadier Thomas Farrell (General Leslie Groves' executive officer) and Rear Admiral William R. Purnell of the Military Policy Committee.
The 509th began replacement of its 14 training Silverplates in February 1945 by transferring four to the 216th Base Unit. In April they began receiving Silverplates of the third modification increment and the remaining ten training B-29s were placed in storage. Each bombardier completed at least 50 practice drops of inert pumpkin bombs and Col. Tibbets declared his group combat-ready. Preparation for Overseas Movement (POM) began in April.
| AAF serial # | Victor # | Name | Crew # | Airplane Commander | USAAF Delivery | Arr. Tinian | Tail Code |
| B-29-36-MO 44-27296 | 84 | Some Punkins | B-7 | Capt. James N. Price | March 19, 1945 | June 14, 1945 | Large A |
| B-29-36-MO 44-27297 | 77 | Bockscar | C-13 | Capt. Frederick C. Bock | March 19, 1945 | June 17, 1945 | Triangle N |
| B-29-36-MO 44-27298 | 83 | Full House | A-1 | Maj. Ralph R. Taylor | March 20, 1945 | June 17, 1945 | Square P |
| B-29-36-MO 44-27299 | 86 | Next Objective | A-3 | Capt. Ralph N. Devore | March 20, 1945 | June 17, 1945 | Triangle N |
| B-29-36-MO 44-27300 | 73 | Strange Cargo | A-4 | Capt. Joseph E. Westover | April 2, 1945 | June 11, 1945 | Large A |
| B-29-36-MO 44-27301 | 85 | Straight Flush | C-11 | Maj. Claude R. Eatherly | April 2, 1945 | June 14, 1945 | Triangle N |
| B-29-36-MO 44-27302 | 72 | Top Secret | B-8 | Capt. Charles F. McKnight | April 2, 1945 | June 11, 1945 | Large A |
| B-29-36-MO 44-27303 | 71 | Jabit III | B-6 | Maj. John A. Wilson | April 3, 1945 | June 11, 1945 | Large A |
| B-29-36-MO 44-27304 | 88 | Up An' Atom | B-10 | Capt. George W. Marquardt | April 3, 1945 | June 17, 1945 | Triangle N |
| B-29-40-MO 44-27353 | 89 | The Great Artiste | C-15 | Capt. Charles D. Albury | April 20, 1945 | June 28, 1945 | Circle R |
| B-29-40-MO 44-27354 | 90 | Big Stink | A-5* | Lt.Col. Thomas J. Classen* | April 20, 1945 | June 25, 1945 | Circle R |
| B-29-45-MO 44-86291 | 91 | Necessary Evil | C-14 | Capt. Norman W. Ray | May 18, 1945 | July 2, 1945 | Circle R |
| B-29-45-MO 44-86292 | 82 | Enola Gay | B-9 | Capt. Robert A. Lewis | May 18, 1945 | July 6, 1945 | Circle R |
| B-29-50-MO 44-86346 | 94 | Luke the Spook | C-12* | Capt. Herman S. Zahn* | June 15, 1945 | August 2, 1945 | Square P |
| B-29-50-MO 44-86347 | 95 | Laggin' Dragon | A-2 | Capt. Edward M. Costello | June 15, 1945 | August 2, 1945 | Square P |
Although all of the B-29's were named as shown, the only nose art applied to the aircraft before the atomic bomb missions was that of Enola Gay. With the exceptions of victors 71 and 94, the others were applied some time in August 1945. Luke the Spook was not named until November 1945, and it is not known if nose art was ever applied to Jabit III, although the version shown at the 509th Yearbook gallery was first shown in 1997.
Color images of 393rd Bomb Squadron nose art
The air echelon began deploying from Wendover June 4, 1945, with the first B-29 arriving at North Field on June 11. The group was assigned to the 313th Bomb Wing, whose four groups had been flying missions against Japan since mid-February, but because of security considerations was given a base area near the airfield on the north tip of Tinian, several miles from the main installations in the center part of the island. Two of the group's bombers were not delivered by Martin-Omaha until early July and remained at Wendover until July 27 to act as transports to Tinian for two of the Fat Man atomic bomb assemblies.
The group was assigned tail markings of a circle outline around an arrowhead pointing forward, but at the beginning of August, after it began flying combat missions, its fifteen B-29's were given the tail markings of other XXI Bomber Command groups as a security measure. The victor numbers previously assigned the aircraft were changed to avoid confusion with B-29s of the groups from whom the tail identifiers were borrowed.
Victor numbers 82, 89, 90, and 91 (including the Enola Gay) carried the markings of the 6th Bomb Group (Circle R); victors 71, 72, 73, and 84 those of the 497th Bomb Group (large "A"); victors 77, 85, 86, and 88 those of the 444th Bomb Group (triangle N); and victors 83, 94, and 95 those of the 39th Bomb Group (square P).
After ground training for the combat crews, the 509th began operations on June 30, 1945, with a calibration flight involving nine of the B-29s on hand. During the month of July and the first eight days of August the thirteen bombers of the 393rd BS flew an intensive training and mission rehearsal program that consisted of:
While this training was taking place, the disassembled components of the first two atomic bombs were transshipped to Tinian by various means. For the uranium bomb code-named Little Boy, the U-235 projectile and bomb pre-assemblies left Hunters Point Naval Shipyard, California, on July 16 aboard the cruiser USS Indianapolis, arriving July 26. That same day three C-54s of the 320th TCS left Kirtland Army Air Field each with one of the U-235 target rings and landed at North Field on July 28.
The components for the bomb code-named Fat Man all arrived by air. On July 26 the bomb's plutonium core (encased in its insertion capsule) and the beryllium-polonium initiator were transported from Kirtland by C-54 in the custody of Project Alberta couriers, also arriving July 28. The pre-assemblies of Fat Man F-31 were picked up by B-29 at Kirtland on July 28 and reached North Field on August 2.
The final item of preparation for the operation came on July 29, 1945. General Carl Spaatz, commanding all strategic bombers in the Pacific, arrived at Tinian with the order for the attack. Drafted by Brig.Gen. Leslie Groves and sent by Gen. George C. Marshall from Potsdam on July 25, the order designated four targets: Hiroshima, Kokura, Niigata, and Nagasaki, and ordered the attack to be made "as soon as weather will permit after about 3 August.
The Hiroshima mission was flown as planned and executed without significant problems or diversion from plan. The Nagasaki mission, however, originally targeted Kokura and encountered numerous problems which resulted in the bombing of the secondary target, a delay in bombing of almost two hours, detonation of the bomb some distance from the designated aiming point, and a diversion of the strike force to emergency landings on Okinawa because of a lack of fuel. However the basic objectives of the mission were met despite the problems.
Lieutenant Jacob Beser flew on both attack aircraft (the only man to do so), although Maj. Charles W. Sweeney and crew observed Hiroshima from The Great Artiste and dropped the bomb on Nagasaki from Bockscar. Lawrence H. Johnston of Project Alberta observed all three nuclear explosions, including the Trinity test.
| Aircraft | Pilot | Call Sign | Mission role |
| Straight Flush | Maj. Claude R. Eatherly | Dimples 85 | Weather reconnaissance (Hiroshima) |
| Jabit III | Maj. John A. Wilson | Dimples 71 | Weather reconnaissance (Kokura) |
| Full House | Maj. Ralph R. Taylor | Dimples 83 | Weather reconnaissance (Nagasaki) |
| Enola Gay | Col. Paul W. Tibbets | Dimples 82 | Weapon Delivery |
| The Great Artiste | Maj. Charles W. Sweeney | Dimples 89 | Blast measurement instrumentation |
| Necessary Evil | Capt. George W. Marquardt | Dimples 91 | Strike observation and photography |
| Top Secret | Capt. Charles F. McKnight | Dimples 72 | Strike spare—did not complete mission |
| Aircraft | Pilot | Call Sign | Mission role |
| Enola Gay | Capt. George W. Marquardt | Dimples 82 | Weather reconnaissance (Kokura) |
| Laggin' Dragon | Capt. Charles F. McKnight | Dimples 95 | Weather reconnaissance (Nagasaki) |
| Bockscar | Maj. Charles W. Sweeney | Dimples 77 | Weapon Delivery |
| The Great Artiste | Capt. Frederick C. Bock | Dimples 89 | Blast measurement instrumentation |
| Big Stink | Maj. James I. Hopkins, Jr. | Dimples 90 | Strike observation and photography |
| Full House | Maj. Ralph R. Taylor | Dimples 83 | Strike spare—did not complete mission |
While the Nagasaki mission was in progress, two B-29's of the 509th took off from Tinian to return to Wendover. Lt.Col. Classen, the deputy group commander, in the unnamed victor 94 and crew B-6 in Jabit III, together with their ground crews, were sent back to stage for the possibility of transporting further bomb assemblies to Tinian. However the plutonium cores were still at Site Y, and on August 13 Gen. Groves ordered that all shipments of material be stopped. His order reached Los Alamos in time to keep the third bomb from being shipped. The first Atomic War lasted 9 days, August 6 through August 15, 1945.
After the Nagasaki mission the group continued combat operations, making another series of pumpkin bomb attacks (12 dropped) on August 14. With the announcement of the Japanese surrender, however, the 509th CG flew three further training missions involving 31 sorties on August 18, 20, and 22, then stood down from operations. The group flew a total of 210 operational sorties from June 30 to August 22, and aborted four additional flights, with only one aircraft failure to take off. 140 involved the dropping of live ordnance. 62 sorties received combat credits for missions flown (49 pumpkin bomb and 13 atomic bomb sorties).
The Group was assigned to Strategic Air Command on March 21, 1946, being one of the first eleven organizations assigned to SAC. At the time SAC was formed, the 509th Composite Group was the only unit to have experience with nuclear weapons and thus is regarded by many historians as the foundation on which SAC was built. In April 1946 many of the group's aircraft deployed to Kwajalein as part of Operation Crossroads, a series of atomic bomb tests. The remainder became the core of two new squadrons activated as part of the group, the 715th Bomb Squadron and the 830th Bomb Squadron.
On July 10, 1946, the group was renamed the 509th Bombardment Group (Very Heavy) and the 320th TCS was disbanded. With the creation of the United States Air Force as a separate service, the group became the combat component of the 509th Bomb Wing on November 17, 1947, although it was not operational until September 14, 1948, when Col. John D. Ryan was named commander.
The group was redesignated as a medium bomb group in 1948 as part of the Strategic Air Command, and acquired an aerial refueling mission with the assignment of KB-29s. Its 27 operational Silverplate B-29s (the 309th had ultimately received 53 of the 65 produced) were transferred in 1949 to the 97th Bomb Wing at Biggs Air Force Base, El Paso, Texas, when the group converted to B-50 Superfortresses.
Its squadrons were removed on February 1, 1951, and assigned directly to the wing, effectively ending its operations. The 509th was inactivated on June 16, 1952 as part of a SAC (and later Air Force-wide) phase-out of groups.
World War II:
Department of the Air Force Special Order GB-294, dated 2 September 1999, awarded the Air Force Outstanding Unit Award (with Valor) to the 509th Composite Group for outstanding achievement in combat for the period 1 July 1945 to 14 August 1945.
In addition to the official insignia the 509th Bomb Wing for B-2 stealth bomber test flights, based in Roswell, New Mexico, sported an informal insignia involving an alien, the legend "To Serve Man" (referring to a famous Twilight Zone episode) and the legend "Gustatus Similis Pullus" or "Tastes Like Chicken" (referring to the possible taste of long pig).
The group was redesignated 509th Operations Group on March 12, 1993, and activated on July 15 as the flying component of the 509th Bomb Wing at Whiteman Air Force Base, Missouri. The 509th is equipped with all 20 of the USAF's B-2 Spirit bombers and its 394th CTS also uses T-38 Talon trainers.