Strategic bombardment in roles and missions In March 1928, commenting on the lack of survivability in combat of his unit's
Keystone LB-7 and
Martin NBS-1 bombers, Lt. Col.
Hugh J. Knerr, commander of the
2nd Bombardment Group at
Langley Field,
Virginia, recommended that the Air Corps adopt two types of all-metal monoplane bombers, a short-range day bomber and a long-range night bomber. Instructors at the
Air Corps Tactical School (ACTS), also then at Langley, took the concept one step further in March 1930 by recommending that the types instead be
light and
heavy, the latter capable of long range carrying a heavy bomb load that could also be used during daylight. The Air Corps in January 1931 "got its foot in the door" for developing a mission for which only it would have capability, while at the same time creating a need for technological advancement of its equipment.
Chief of Naval Operations Admiral
William V. Pratt wanted approval of his proposition that all naval aviation including land-based aircraft was by definition tied to carrier-based fleet operations. Pratt reached an agreement with new Army Chief of Staff
Douglas MacArthur that the Air Corps would assume responsibility for coastal defense (traditionally a primary function of the Army but a secondary, wartime function of the Navy) beyond the range of the Army's Coast Artillery guns, ending the Navy's apparent duplication of effort in coastal air operations. The agreement, intended as a modification of the Joint Action statement on coastal defense issued in 1926, was not endorsed by the Joint Army-Navy Board and never had authority other than a personal agreement between the two heads of service. Though the Navy repudiated the statement when Pratt retired in 1934, the Air Corps clung to the mission, and provided itself with the basis for development of long-range bombers and creating new doctrine to employ them. The formulation of theories of
strategic bombing gave new impetus to the argument for an independent air force. Strategic or long-range bombardment was intended to destroy an enemy's industry and war-making potential, and only an independent service would have a free hand to do so. But despite what it perceived as "obstruction" from the War Department, much of which was attributable to a shortage of funds, the Air Corps made great strides during the 1930s. A doctrine emerged that stressed precision bombing of industrial targets by heavily armed long-range aircraft. This doctrine resulted because of several factors. The Air Corps Tactical School moved in July 1931 to
Maxwell Field,
Alabama, where it taught a 36-week course for junior and mid-career officers that included military aviation theory. The Bombardment Section, under the direction of its chief, Major
Harold L. George, became influential in the development of doctrine and its dissemination throughout the Air Corps. Nine of its instructors became known throughout the Air Corps as the "
Bomber Mafia", eight of whom (including George) went on to be generals during World War II. Conversely, pursuit tacticians, primarily Capt.
Claire Chennault, Chief of the school's Pursuit Section, found their influence waning because of repeated performance failures of pursuit aviation. Finally, the doctrine represented the Air Corps' attempt to develop autonomy from the General Staff, which enforced subordination of the air arm by limiting it to support of ground forces and defense of United States territory.
Technological advances in bombers New bomber types under development clearly outperformed new pursuit types, particularly in speed and altitude, then considered the primary defenses against interception. In both 1932 and 1933, large-scale maneuvers found fighters unable to climb to altitude quickly enough to intercept attacking
B-9 and
B-10 prototypes, a failure so complete that Westover, following the 1933 maneuvers, actually proposed elimination of pursuits altogether. 1933 was a pivotal year in the advancement of aviation technology in which the all-metal airplane came of age, "practically overnight" in the words of one historian, because of the availability of the first practical
variable-pitch propeller. Coupled with "best weight" design of airframes, the controllable pitch propeller resulted in an immediate doubling of speeds and operating ranges without decreasing aircraft weights or increasing engine horsepower, exemplified by the civil
Douglas DC-1 transport and the military Martin B-10 bomber. The B-10 featured innovations that became standard internationally for the next decade: an all-metal low wing monoplane, closed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay,
high-lift devices and full engine cowlings. The B-10 proved to be so superior that as its 14 operational test models were delivered in 1934 they were fed into the Air Corps mail operation, and despite some glitches caused by pilot unfamiliarity with the innovations, were a bright spot. The first action to repair the damaged image of the Air Corps involved the movement of ten YB-10s from Bolling Field to Alaska, ostensibly for an airfield survey, but timed to coincide with the release of the Baker Board's report in July. The successful development of the B-10 and subsequent orders for more than 150 (including its B-12 variant) continued the hegemony of the bomber within the Air Corps that resulted in a feasibility study for a 35-ton 4-engined bomber (the
Boeing XB-15). While it was later found to be unsuitable for combat because the power of existing engines was inadequate for its weight, the XB-15 led to the design of the smaller Model 299, later to become the
Boeing B-17 Flying Fortress, whose first flight was at the end of July 1935. By that time the Air Corps had two projects in place for the development of longer-ranged bombers, Project A for a bomber with a ferry range of , and Project D, for one of a range of up to . In June 1936 the Air Corps requested 11 B-15s and 50 B-17s for reinforcing hemispheric defense forces in Hawaii, Alaska, and Panama. The request was rejected on the basis that there were no strategic requirements for aircraft of such capabilities.
General Staff resistance to Air Corps doctrine The Army and Navy, both cognizant of the continuing movement within the Air Corps for independence, cooperated to resist it. On 11 September 1935, the Joint Board, at the behest of the Navy and with the concurrence of MacArthur, issued a new "Joint Action Statement" that once again asserted the limited role of the Air Corps as an auxiliary to the "mobile Army" in all its missions, including coastal defense. The edict was issued with the intent of again shoving an upstart Air Corps back into its place. However, the bomber advocates interpreted its language differently, concluding that the Air Corps could conduct long-range reconnaissance, attack approaching fleets, reinforce distant bases, and attack enemy air bases, all in furthering its mission to prevent an air attack on America. A month later (15 October 1935), the General Staff released a revision of the doctrinal guide for the Air Corps, training regulation TR 440-15
Employment of the Air Forces of the Army. A year earlier MacArthur had changed TR 440-15 to clarify "the Air Corps's place in the scheme of national defense and ... (to do away with) ... misconceptions and interbranch prejudices." The General Staff characterized its latest revision as a "compromise" with airpower advocates, to mitigate public criticism of the Joint Action Statement, but the newest revision parroted the anti-autonomy conclusions of the Drum and Baker Boards, and reasserted its long-held position (and that of the Secretary Dern) that auxiliary support of the ground forces was the primary mission of the Air Corps. TR 440-15 did acknowledge some doctrinal principles asserted by the ACTS (including the necessity of destroying an enemy's air forces and concentrating air forces against primary objectives) and recognized that future wars would probably entail some missions "beyond the sphere of influence of the Ground Forces" (strategic bombardment), but it did not attach any importance to prioritization of targets, weakening its effectiveness as doctrine. TR 440-15 remained the doctrinal position of the Air Corps until it was superseded by the first Air Corps Field Manual, FM 1–5
Employment of Aviation of the Army, on 15 April 1940. In the fall of 1937, the
Army War College's course on the use of airpower reiterated the General Staff position and taught that airpower was of limited value when employed independently. Using attaché reports from both
Spain and
Ethiopia, and endorsed by a senior Air Corps instructor, Col.
Byron Q. Jones, the course declared that the Flying Fortress concept had "died in Spain", and that airpower was useful mainly as "long range artillery." Air Corps officers in the G-3 Department of the General Staff pointed out that Jones' conclusions were inconsistent with the revised TR 440-15, but their views were dismissed by Deputy Chief of Staff Maj. Gen.
Stanley Embick with the comment: "No doctrine is sacrosanct, and of all military doctrines, that of the Air Corps should be the last to be so regarded." At the same time, the General Staff ordered studies from all the service branches to develop drafts for the coming field manuals. The Air Corps Board, a function of the ACTS, submitted a draft in September 1938 that included descriptions of independent air operations, strategic air attacks, and air action against naval forces, all of which the General Staff rejected in March 1939. Instead, it ordered that the opening chapter of the Air Corps manual be a doctrinal statement developed by the G-3 that "left little doubt" that the General Staff's intention was "to develop and employ aviation in support of ground forces." The Air Corps Board, on the orders of Arnold, developed a secret study for "defense of the
Monroe Doctrine" that recommended development of long-range, high altitude, high-speed aircraft for bombardment and reconnaissance to accomplish that defense. The War Department, seeking to stifle procurement of the B-17 while belatedly recognizing that coordinated air-ground support had been long neglected, decided that it would order only two-engined "light" bombers in fiscal years 1939 through 1941. It also rejected further advancement of Project A, the development program for a very long range bomber. In collaboration with the Navy, the Joint Board (whose senior member was Army Chief of Staff Gen.
Malin Craig) on 29 June 1938 issued a ruling that it could foresee no use for a long-range bomber in future conflict. As a direct result, the last planned order of long-range bombers (67 B-17s) was cancelled by Craig and a moratorium on further development of them was put into effect by restricting R&D funding to medium and light bombers. This policy would last less than a year, as it went against not only the trends of technological development, but against the geopolitical realities of coming war. In August 1939 the Army's research and development program for 1941 was modified with the addition of nearly five million dollars to buy five long-range bombers for experimental purposes, resulting on 10 November 1939 in the request by Arnold of the developmental program that would create the
Boeing B-29 Superfortress, which was approved on 2 December. Between 1930 and 1938 the Air Corps had obtained a mission in coastal defense that justified both the creation of a centralized strike force and the development of four-engined bombers, and over the resistance of the General Staff
lobbied for another mission, strategic bombardment, with which it could persuasively argue for independence from the Army. The cost of the General Staff's resistance in terms of preparedness had been severe, however. Its policies had resulted in the acquisition of obsolete aircraft as first-line equipment, stifled design development in the private sector of better types, retarded the development of radar and ordnance, and handicapped training, doctrine, and offensive organization by reneging on commitments to acquire the B-17. "From October 1935 until 30 June 1939, the Air Corps requested 206 B-17's and 11 B-15's. Yet because of cancellations and reductions of these requests by the War Department, 14 four-engine planes were delivered to the air force up to the outbreak of World War II in September 1939."
GHQ Air Force A major step toward creation of a separate air force occurred on 1 March 1935 with the activation of a centralized, air force-level command headed by an aviator answering directly to the Army
Chief of Staff. Called the
General Headquarters Air Force, the organization had existed in Army planning since 1924 as a subordinate element of Army General Headquarters, which would be activated to control all Army units in case of war mobilization. In anticipation of military intervention in Cuba in 1933, the headquarters had been created on 1 October but not staffed. The Drum Board of 1933 had first endorsed the concept, but as a means of reintegrating the Air Corps into control by the General Staff, in effect reining it in. Among the recommendations of the
Baker Board, established in the wake of the Air Mail scandal, was that the proposals of the Drum Board be adopted: an increase in strength to 2,320 aircraft and establishment of GHQ Air Force as a permanent peacetime tactical organization, both to ameliorate the pressures for a separate air force and to exploit emerging capabilities in airpower. In the absence of a general headquarters (i.e. peacetime), GHQ Air Force would report to the General Staff. The War Plans Division of the Army reacted to the recommendations of the Baker Board by insisting that men and modern equipment for seven army divisions be procured before any increase in the Air Corps was begun, and opposed any immediate attempt to bring the Air Corps up to the 1,800 plane-strength first authorized in 1926, for fear of antagonizing the Navy. President Roosevelt approved an open-ended program to increase strength to 2,320 aircraft (albeit without any proviso for funding) in August 1934, and Secretary Dern approved the activation of GHQ Air Force in December 1934. GHQ Air Force took control of all combat air units in the United States from the jurisdiction of
corps area commanders, where it had resided since 1920, and organized them operationally into a strike force of three wings. The GHQ Air Force remained small in comparison to European air forces. On its first day of existence, the command consisted of 60 bombers, 42 attack aircraft, 146 pursuits, and 24 transports, amounting to 40% of strength in the
tables of organization. Administratively it organized the forces into four geographical districts (which later became the first four numbered air forces) that paralleled the four field army headquarters created in 1933. The General Staff perceived its creation as a means of lessening Air Corps autonomy, not increasing it, however, and GHQ Air Force was a "coordinate component" equal to the Air Corps, not subject to its control. The organizations reported separately to the Chief of Staff, the Air Corps as the service element of the air arm, and GHQAF as the tactical element. However, all GHQ Air Force's members, along with members of units stationed overseas and under the control of local ground commanders, remained part of the Air Corps. This dual status and division of authority hampered the development of Air Corps for the next six years, as it had the Air Service during World War I, and was not overcome until the necessity of expanding the force occurred with the onset of World War II. The commanding general of GHQ Air Force, Maj. Gen.
Frank M. Andrews, clashed philosophically with Westover over the direction in which the air arm was heading, adding to the difficulties, with Andrews in favor of autonomy and Westover not only espousing subordination to the Army chain of command but aggressively enforcing his prohibitions of any commentary opposed to current policy. Andrews, by virtue of being out from Westover's control, had picked up the mantle of the radical airmen, and Westover soon found himself on "the wrong side of history" as far as the future of the Air Corps was concerned. Lines of authority were also blurred as GHQ Air Force controlled only combat flying units within the continental United States. The Air Corps was responsible for training, aircraft development, doctrine, and supply, while the ground forces corps area commanders still controlled installations and the personnel manning them. The issue of control of bases was ameliorated in 1936 when GHQAF bases were exempted from corps area authority on recommendation of the Inspector General's Department, but in November 1940 it was restored again to Corps Area control when Army General Headquarters was activated. . In January 1936, the Air Corps contracted with
Boeing for thirteen
Y1B-17 Flying Fortress prototypes, enough to equip one squadron for operational testing and a thirteenth aircraft for stress testing, with deliveries made from January to August 1937. The cost of the aircraft disturbed
Secretary of War Harry Woodring, who denied requests for further purchases, so that although the air arm embraced strategic bombing as its primary doctrine after the creation of GHQ Air Force, by 1938 there were still only thirteen strategic bombers on hand. On 18 March 1938 Secretary Woodring implemented a plan that would have included the purchase of 144 four-engine bombers but approval was reversed in July when the moratorium against the long-range bomber program was imposed by the Joint Board. The purchase of 67 B-17s (five squadrons) in FY 1940 as an increment of the Woodring program, using carryover funds, was cancelled by Craig. The moratorium also resulted from the enmity of the Navy incurred by the Air Corps on 12 May 1938 when it widely publicized the
interception of the Italian ocean liner Rex by three B-17s while it was off-shore of New York City. Possibly under pressure from the Navy, Craig placed a limit of on all future off-shore flights by the Army. The services together issued a revised Joint Action statement in November reasserting that the mission of the Air Corps in coastal defense was only for supporting the Navy if called upon to do so, while simultaneously authorizing for the Navy the long-range shore-based coastal patrol mission denied the Air Corps. Westover, who stridently opposed cancellation of the Woodring program, was killed in an air crash on 21 September 1938 and was succeeded by Arnold. ==Modernization and expansion of the force==