ASSC to USAAF (1913-1940)



At the peak of its strength in World War II, the United States Army Air Forces (USAAF) had more than 2.400.000 men and women in uniform. There were pilots, navigators, bombardiers, gunners, and radio operators, clerks and typists, artists and flutists, teachers, mechanics, statisticians, and engineers – for it took many talents and skills to conduct and support the war in the air. All these persons, from privates to generals, had to be welded into an organization capable of giving direction and coordination to their diverse activities. For combat the men were formed into squadrons, and squadrons into groups. Above the groups were wings, and wings were organized into commands, and commands into the 16 air forces of the AAF. The upper part of the structure had to be built while the war was on, but the foundation was old. Some of the squadrons, two of the groups, and one wing had combat records from the First World War. One squadron, the oldest in the Air Force, could trace its history back to 1913.

recpost-tn-1The Army had established an Aeronautical Division in the Signal Corps on August 1 1907 and had acquired its first plane in 1909. Army men had learned to fly, but for some time the aviators were not organized into units for operations. Consequently, in 1913, when relations between the United States and Mexico were strained as a result of a revolution in Mexico, there was no aviation unit for service along the Mexican border. The Army, however, sent some of its pilots and planes to Texas, and on March 5 1913 these were formed into the 1st Aero Squadron, a provisional organization made up of two companies.

Later that year, in December, after the provisional unit had moved to San Diego for training, it was organized officially as an Army Squadron. Following Pancho Villa’s raid on Columbus, New Mexico, in March 1916, the squadron joined the force that Brig Gen John J. Pershing organized to try to capture this Mexican bandit.

Thus the 1st Aero Squadron, which provided communication and reconnaissance services during the Mexican expedition, was the first American aviation unit to take the field for a military campaign. Meanwhile, although war had broken out in Europe, little progress had been made toward expanding the Army’s air arm. Congress created an Aviation Section in the Signal Corps by an act approved on July 18 1914, but the legislators provided little money for the new service. Moreover, the Signal Corps naturally used the meager resources to develop aviation as a means of communication, observation, and reconnaissance, rather than as an instrument for combat. One company of the 2nd Aero Squadron was organized in 1915 and sent to the Philippines. The following year plans were made for five more squadrons. One, the 7-AS, was formed in February 1917 for duty in the Panama Canal Zone. Another, the 6-AS, was organized in Hawaii in March 1917. Three others, the 3-AS the 4-AS and the 5-AS, were being formed in the United States at the time the nation entered World War I in April 1917.

180px-siouxWorld War One

Gen John J. Pershing, who became commander of the American Expeditionary Forces (AEF) soon developed a plan for the deployment of 260 combat squadrons to France. Later the plan was revised with the number of squadrons reduced to 202, all of which were to be at the front by June 30 1919. In Pershing’s view, the main functions of the AEF’s Air Service were to drive off hostile aircraft and to obtain information about enemy movements. Half of the 202 squadrons, therefore, were to be observation units assigned to 3 Armies and 16 Corps.

capt-rickenbackerOf the remainder, 60 were to be pursuit squadrons. But the plan also provided for 27 night bombardment and 14 day bombardment squadrons. The first American aviation unit to reach France was the 1-AS, an observation organization which sailed from New York in August 1917 and arrived at Le Havre on Sept 3. As other squadrons were organized at home, they too were sent overseas, where they continued their training. It was February 1918 before any American aviation squadron entered combat, but by Armistice Day, Nov 11 1918, 45 combat squadrons (20 pursuit, 18 observation, and 7 bombardment) had been assigned to the front. During the war the aero squadrons played important roles in such famous battles as the Aisne-Marne Saint-Mihiel, and the Meuse-Argonne. Some, like the 94th Squadron that had Capt Eddie Rickenbacker for its commander, or the 27th that had ‘balloon buster’ Frank Luke as one of its aviators, made distinguished records in combat.

Observation planes frequently operated individually, and pursuit pilots often went out alone to attack a balloon or to meet the enemy in a dogfight. But the tendency was toward formation flying for pursuit as well as for bombardment operations. The dispersal of squadrons among the various army organizations made it difficult, however, to obtain coordination of aerial activities. Some higher organization was required. Squadrons with similar functions were formed into groups, the first of these being the 1st Corps Observation Group, organized in April 1918. The following month the 1st Pursuit Group was formed, and by November 11 1918 the AEF had 14 groups (7 observation, 5 pursuit, and 2 bombardment). In July 1918 the AEF organized its first wing, made up of the 2d and 3d Pursuit Groups and, later the 1st

frank-lukeDay Bombardment Group

Some airmen, including William ‘Wild Bill’ Mitchell, were advocating the formation of an air force that would concentrate control over military aviation for heavy blows against the enemy. In September 1918, for the Allied assault against the German salient at Saint-Mihiel, Mitchell brought together almost 1.500 American and French planes for coordinated operations in which observation and pursuit supported ground forces, while the other two-thirds of the air force bombed and strafed behind the lines.

Later, during the Meuse-Argonne offensive, Mitchell attained a somewhat smaller concentration of air power for use in keeping the enemy on the defensive. In France the Air Service was part of Pershing’s expeditionary force. In the United States the Chief Signal Officer was responsible for organizing, training, and equipping aviation units until May 21 1918. At that time the President created a Bureau of Aircraft Production and made it responsible for aeronautical equipment; training of personnel and units was the responsibility of the Division of Military Aeronautics, which had been created by the War Department on April 27 1918.

Although the bureau and division were recognized by the War Department on May 24 1918 as forming the Army’s Air Service, no Director of Air Service was appointed until August 27 1918.

1919 – 1939

After the war the Army quickly demobilized most of its air arm, including the wing, all of the groups, and most of the squadrons. Almost immediately, however, it began to create new organizations for peacetime service. In many instances these new organizations had no connection with those that had been active during the war. For example, at Selfridge Field in August 1919 the Army organized a 1st Pursuit Group that was in no way related to the AEF’s 1st Pursuit Group, which had been demobilized in France in December 1918. A little later, however, the Army began a series of organizational actions that eventually enabled many active organizations to trace their histories back to World War I. In the case of the 1st Pursuit Group, for instance, the Army reconstituted the World War I group of that name and consolidated it with the active group. This process of reconstituting old units and consolidating them with active units has continued up to the present time. In 1920 an act of Congress approved on June 4, created the Air Service as a combatant arm of the United States Army. But the Air Service and the Air Corps that replaced it in 1926 (act of July 2) did not control the combat units, for their training and operations came under the jurisdiction of ground forces. With this arrangement the Air Service and Air Corps were responsible for matters relating to personnel and materiel logistics, particularly training individual pilots and other specialists, and developing, procuring, storing, and distributing aeronautical equipment.


The composition, organization, and command of the combat elements of the air arm during the 1920’s and early 1930’s were based on principles laid down by the WD General Staff in 1920. These principles, as they related to military aviation, were reflected in a war plan that called for the following aviation organizations as part of an expeditionary force :

1 observation squadron for each of 54 divisions
1 observation squadron for each of 18 corps
1 observation group (4 squadrons), 1 attack wing (1 att. & 2 pur. groups), for each of 6 armies
1 attack wing, 1 observation group, 1 bombardment group for General Headquarters (GHQ).

Thus the war plan placed the greatest emphasis on observation aviation. It gave lesser roles to pursuit aviation, which was to destroy enemy planes and assist in attacking enemy troops and other objectives, and to attack aviation, which was to harass the enemy’s ground forces. It assigned a minor place to bombardment aviation, with the mission of destroying military objectives in the combat theater and in the enemy’s zone of interior. Furthermore, it placed aviation under the command of ground officers at division, corps, army, and GHQ levels. As a result, the structure was condemned by Billy Mitchell and other Air Service officers who discounted the importance of observation aviation, sought recognition for bombardment as a major instrument of warfare, desired a greater proportion of pursuit units for counter-air operations, and wanted aviation units organized as an air force under the command of airmen. One of the important facets of the history of the Army’s air arm during the 1920’s and 1930’s was the conflict between air and ground officers over the composition, organization, and command of military aviation. While this is not the place for a detailed review of that subject, the progress that the airmen made toward gaining acceptance for their point of view is reflected in organizational changes mentioned in subsequent paragraphs. The principles behind the war plan were applied to the smaller peacetime organization that was to be capable of rapid expansion in an emergency. For several years the striking force based in the United States consisted of three groups :

1st Pursuit
2nd Bombardment
3rd Attack.


There also was one observation group (the 9th), and there was one observation squadron for each of the Army corps. During the same period there were three composite groups on foreign service :

4th in the Philippines
5th in Hawaii
6th in Panama


In 1926 the Army began to expand its air arm, and in the years that followed new groups were activated :

18th Pursuit (in Hawaii) in 1927
7th Bombardment in 1928
12th Observation
20th Pursuit in 1930
8th Pursuit in 1931
17th Pursuit in 1931
16th Pursuit (in the Canal Zone)
19th Bombardment in 1932.

Consequently by the end of 1932 there were 15 groups, (45 squadrons). The distribution of the squadrons by function is significant. The number of attack squadrons (4) was the same as it had been a decade earlier, while the strength in observation aviation had decreased from 14 to 13 squadrons. The growth had, therefore, been in other types of aviation, the number of bombardment squadrons having increased from 7 to 12, and pursuit squadrons from 7 to 16. Five more pursuit squadrons were activated in 1933, bringing the total strength to 50 squadrons. The most important change in the combat organization of the air arm in the two decades between World Wars I and II came on March 1 1935. At that time the WD established General Headquarters Air Force (GHQAF) and placed it under the command of an air officer to serve as an air defense and striking force. Some observation units remained assigned to corps areas, but all the pursuit, bombardment, and attack units in the US became part of the new combat organization. The combat elements of GHQAF were organized into three wings :

1st Wing (Hqs March Field) had two bombardment groups, one attack group, and three observation squadrons
2nd Wing (Langley Field) had two bombardment and two pursuit groups, plus three observation squadrons
3rd Wing (Barksdale Field) had an attack and a pursuit group, plus one bombardment, one attack, and two pursuit squadrons

The commanding general of GHQAF, who reported to the Army’s Chief of Staff and was to report to the commander of the field force in time of war, was responsible for the organization, training, and operations of this air force. The Chief of the Air Corps still retained the responsibilities associated with personnel and material logistics. The change of the 9th Group from observation to bombardment in 1935 should be noted because that re-designation was an indication of the decline of observation and the growth of bombardment aviation. Two years later the 12th Observation Group was inactivated. And the same year (1937) the 10th Transport Group, the first group of its kind, was activated. But there were no other significant changes, the number of groups remaining at 15 (10 in the United States and 5 on foreign service), until 1939.


World War II

In January 1939, President Franklin D. Roosevelt asked Congress to strengthen America’s air power, which, the President said, was ‘utterly inadequate’. On September 1, 1939, Hitler attacked Poland, and the Second World War began. In the months that followed, as Axis forces won one victory after another, the Army’s air arm expanded rapidly. By the end of 1940 there were 30 groups. Within another year, that is, by the time the Japanese attacked Pearl Harbor and the US entered the war, the number of active groups had increased to 67, but many of them were still in the process of being organized and few had aircraft suitable for combat. The air arm grew even more rapidly in the months following Pearl Harbor, and by the end of 1943 there were 269 groups. At that time 133 of the groups were in the US. 77 were being manned or trained; 56, which provided the strategic reserve, served as part of the defense force, as operational training units OTU that prepared new units for combat, or as replacement training units RTU that trained replacements for organizations overseas.

Early in 1944 most of the OTU’s and RTU’s were inactivated or disbanded, the training activities being given to base units. As a result the number of combat groups fell to 218, but the formation of new groups brought the figure up to another peak of 243 in February 1945. When Allied forces landed on the beaches of Normandy on June 6 1944, the United States had 148 combat groups in the European, African, Middle Eastern Theater for the war against Germany. By August 1945, when combat operations in the Asiatic-Pacific Theater came to an end, the United States had 86 groups in the war against Japan. In addition to the expansion, other important changes had taken place in the air arm. By 7 December 1941 more emphasis was being placed on bombardment. Of the 67 groups active at that time, 26 were bombardment organizations; half of the 26 were heavy and the other half were medium and light bombardment groups, the light groups having replaced the attack organizations of an earlier time. There also were 26 pursuit, 9 observation, and 6 transport groups. During the war, pursuit units were re-designated fighter, observation became reconnaissance, and transport became troop carrier. With the development of B-29 aircraft, very heavy bombardment organizations were added to the combat force. In the spring of 1945, when America’s air strength in the overseas theaters of operations reached its peak, the 243 combat groups of the AAF were divided as follows :

25 very heavy bombardment groups
72 heavy bombardment groups
20 medium bombardment groups
8 light bombardment groups
71 fighter groups
29 troop carrier groups
13 reconnaissance groups
5 composite groups

At the same time there were 65 separate squadrons, mostly reconnaissance and night fighter, which were not assigned to groups but to higher echelons of organization. As the number of groups increased, the number of wings multiplied. Earlier, during World War I and in GHQAF, wings had been composite organizations, that is, had been made up of groups with different kinds of missions. Most of the wings of World War II, however, were composed of groups with similar functions. The growth of the air arm resulted in important organizational changes and developments above the group and wing levels. The separation of the combat organization (GHQAF) from the logistic organization (Air Corps) created serious problems of coordination. To correct this condition, GHQAF was placed under the Chief of the Air Corps, Maj Gen Henry H. Arnold, in March 1939. The two organizations were separated again in November 1940, but about the same time Arnold joined the War Department General Staff as Deputy Chief of Staff for Air, a position that enabled him to coordinate the two sections of the air arm. On June 20 1941 the War Department created the Army Air Forces with the Air Corps and GHQAF, the latter re-designated Air Force Combat Command, as its major components and with Arnold as chief. In an Army reorganization on March 9 1942 the Air Corps and Air Force Combat Command were discontinued and Arnold was made Commanding General of Army Air Forces.


During the war most of the AAF’s combat groups and wings were assigned to numbered air forces. The first four of these air forces had their origins late in 1940 when GHQAF was becoming so large that its headquarters could not exercise adequate control over the training and operations of the various GHQAF organizations. General Headquarters Air Force was subdivided, therefore, into four air districts (Northeast, Northwest, Southeast, and Southwest), which were re-designated First, Second, Third, and Fourth Air Forces early in 1941. These four air forces remained in the United States throughout the war, but others were established for service overseas : the Fifth, Seventh, Tenth, Thirteenth, Fourteenth, and Twentieth served in the Asiatic-Pacific Theater; the Eighth, Ninth, Twelfth, and Fifteenth operated in the European-African-Middle Eastern Theater, the Eighth being redeployed to the Pacific after the war ended in Europe; the Sixth was in the Panama Canal Zone and the Eleventh in Alaska. Some air forces, particularly the larger ones, had subordinate commands (or sometimes divisions) that provided an additional echelon of organization, by bringing together wings (or groups) with similar functions. An air force, such as the Ninth, could have a bomber, a fighter, a troop carrier, and a tactical air command, the number and kind depending upon the size, functions, and peculiar needs of the air force.


There also were some separate commands, such as the Antisubmarine Command, which were not assigned to numbered air forces. The arrangement of the various layers of organization is best seen by looking at the organizational position of some particular squadron, such as the 93d Bombardment Squadron, which took part in the B-29 offensive against Japan in 1945. That squadron was assigned to the 19th Bombardment Group, of the 314th Bombardment Wing, of the XXI Bomber Command, of the Twentieth Air Force. But the organization was much more complex than is indicated by such a chain, for operational and administrative requirements resulted in the establishment of organizations above the numbered air forces. There was, for example, the US Strategic Air Forces in Europe, which had some administrative control over both the Eighth and Ninth Air Forces (the one engaged primarily in strategic and the other in tactical operations), and which exercised some operational control over the two strategic air forces in Europe (the Eighth in England and the Fifteenth in Italy). Furthermore, American organizations sometimes became part of combined (i.e., Allied) commands. In April 1942, for instance, an organization called Allied Air Forces was created in Australia to control operations of Australian, Dutch, and American air forces; and in February 1943 American, British, and French elements in North Africa were combined to form the Northwest African Air Forces. The complexity of these organizational arrangements was compounded by the assignment of AAF units overseas to United States Army organizations, and by the relationships of those Army organizations to joint (i.e., Army-Navy) and combined commands. This volume is not concerned with all of this vast organization but with the AAF structure from groups to numbered air forces. Within those limits, the major attention is focused on the groups, the basic operational organizations in the aerial war that America fought in the years between the attack on Pearl Harbor on 7 December 1941 and the Japanese surrender on 2 September 1945.

Aeronautical Division, Signal corps
Officer in Charge :

Capt Charles DeF Chandler, 1 Aug 1907
Capt A. S. Cowan, 1 July 1910
Capt Charles DeF Chandler, 20 Jun 1911
Lt Henry H Arnold, 18 Nov 1912
Maj Edgar Russell, 15 Dec 1912
Lt Col Samuel Reber, 10 Sep 1913 – 18 Jul 1914

Aviation Section, Signal Corps
Officer in Charge :

Lt Col Samuel Reber, 18 Jul 1914
Lt Col George O Squier, 20 May 1916
Lt Col J B Bennett, 19 Feb 1917
Maj Benjamin D Foulois, 30 Jul 1917
Brig Gen A. L. Dade, 12 Nov 1917
Col Laurence Brown, 28 Feb 1918 – 21 May 1918

Division of Military Aeronautics
Director :
Maj Gen William L Kenly, 27 Apr 1918
(under Director, Air Service after 27 Aug 1918)

Bureau of Aircraft Production
Director :

Mr John D Ryan, 21 May 1918
(under Director, Air Service after 27 Aug 1918)

Air Service
Director :

Mr John D Ryan, 27 Aug 1918
Maj Gen Charles T Menoher, 23 Dec 1918 – 4 Jun 1920
Chief :

Maj Gen Charles T Menoher, 4 Jun 1920
Maj Gen Mason M Patrick, 5 Oct 1921 – 2 Jul 1926

Air Corps
Chief :

Maj Gen Mason M Patrick, 2 Jul 1926
Maj Gen J E Fechet, 14 Dec 1927
Maj Gen Benjamin D Foulois, 19 Dec 1931
Maj Gen Oscar Westover, 22 Dec 1935
Maj Gen Henry H Arnold, 22 Sep 1938
Maj Gen George H Brett, 30 May 1941
(under Chief, AAF after 20 Jun 1941).

General Headquarters Air Force, re-designated Air Force Combat Command
Commanding General :

Maj Gen Frank M Andrews, 1 Mar 1935
Lt Gen Delos C Emmons, 1 Mar 1939
(under Chief, AAF after 20 Jun 1941)

Army Air Forces
Chief : Lt Gen Henry H Arnold, 20 Jun 1941 – 9 Mar 1942
CG : General of the Army Henry H Arnold, 9 Mar 1942
Gen Carl Spaatz, 15 Feb 1946 – 26 Sep 1947


For all purposes :
European Center of Military History
Gunter ‘Doc Snafu’ Gillot
rue des Thiers 8
Francorchamps 4970
Email : gunter [at]

Thank You for your support !

(NB : Published for Good – March 2019)

This site uses Akismet to reduce spam. Learn how your comment data is processed.