Tag: Imperial Japanese Army Air Service

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 3 – 1937-41

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 3 – 1937-41

By Justin Pyke

Editorial Note: In the final part of a three-part article, Justin Pyke examines American intelligence assessments of Japanese air power during the inter-war years. This final part examines issues between 1937 and the outbreak of war between America and Japan in 1941. Part one and two of this article can be found here and here.

Japan’s air services had successfully weaned themselves off of their foreign dependence by 1937. American intelligence assessments continued to identify the strategic and industrial weaknesses of Japanese air power accurately but became poor concerning technology and tactics. Japanese information security was tighter than it had ever been. Hence, American observers formed their conclusions through open sources and preconceived notions. When evidence emerged contradicting the prevailing view of Japan’s lack of technological innovation, they were ignored or explained away. Assessments of Japanese personnel began to swing toward a consistently negative view. These failures in assessing Japanese technology, tactics, and personnel from 1937-41 contributed to the defeats at the outset of the Pacific War.

Zero
A captured Mitsubishi ARM ‘Zero’ in flight, c. 1944 (Source: National Naval Aviation Museum)

The Americans had relied on access to Japanese air stations and factories to gain their information until the early 1930s. This avenue was closed with the start of the war in China. In place of the old sources, American observers came to rely extensively on open sources, like official Japanese press releases, supplemented with the precious little information that could be drawn from chance sightings of Japanese aircraft by Westerners.[1] A meaningful assessment of Japanese air power’s performance in China, or detailed technical information of a specific aircraft, would surface on occasion. The information gained from open sources at best-reiterated views that had been in place for almost two decades and at worst became more critical and inaccurate about Japanese capabilities.

American assessments of the Japanese aviation industry remained accurate, despite Japan’s turn towards tight information security. However, the preconception that Japan could not innovate technologically remained pervasive. A July 1937 report was typical. It acknowledged the advances made by the Japanese aviation industry, accurately identified the numerous weaknesses present, and stated that a ‘dearth of local inventive ability’ was a critical failure.[2] Another report referred to the numerous industrial weaknesses as a ‘cancer,’ and went on to claim that Japan continued to rely on copies of foreign aircraft, acquired either through production licenses or ‘outright mimicry.’[3] American assessments combined recognition of the real weaknesses of Japan’s aviation industry with the fiction that it still relied on the copying of foreign aircraft designs.

The American emphasis on Japanese industrial weakness was warranted. The continued shortage of machine tools, skilled labour, heavy equipment, and modern industrial techniques contributed to Japan’s lack of an aircraft reserve, slower rates of production, poor quality and quantity of spare parts, and the numerous other issues that undermined Japanese air power.[4] Greg Kennedy has emphasised this point when he stated that to view:

[tactical] success as demonstrative of the overall ability of Japan to manifest effective, modern air power is to misunderstand fundamentally the core attributes of air power.[5]

Ultimately, the weaknesses of Japanese industry identified by the Americans before the war worked to cripple the offensive capabilities of the Imperial Japanese Army Air Service (IJAAS) and Imperial Japanese Naval Air Service (IJNAS) during it.

Ki-61_at_Fukuoka_in_1945
A Kawasaki Ki-61 ‘Tony’ of the 149th Shimbu Unit at Ashiya airfield in Fukuoka, Japan, c. 1945 (Source: Wikimedia)

The most egregious error in American reporting from mid-1937 onward concerned the preconception that Japan was incapable of designing its own aircraft. Exceptions to this trend did exist, but they were easily drowned out by the overwhelming number of reports that reiterated the same trope of Japanese unoriginality.[6] Fictional aircraft were given corresponding European designs that the Japanese supposedly had copied.[7] When the Americans received hard evidence of Japanese technological innovation, these indicators were ignored or misunderstood. Excellent American intelligence on the B5N Carrier Attack Bomber (‘Kate’) was not used as evidence that Japan had moved away from copying foreign designs.[8] The G3M was immediately assumed to be a copy of the German Junkers Ju-86, while another report stressed the bomber was a Heinkel design with Junkers’ ailerons. In fact, the superlative bomber was indigenous in origin.[9] Even when American observers disagreed on what the aircraft was a copy of, there was no doubt that it had to be a copy of something.

These preconceptions were all the more dangerous as Japan introduced new aircraft that it would use against the West in 1941. The most famous of these was the A6M Carrier Fighter (‘Zero’/‘Zeke’). Despite some accurate reporting on the aircraft, it remained largely unknown in Western aviation circles.[10] In one instance, the testimony of a captured Japanese bomber pilot caused confusion when he explained that the A6M was designed to dive on the enemy, then zoom upwards and prepare for another dive, but not to engage in extensive combat aerobatics. This reflected IJNAS fighter doctrine, which was similar to that of the Americans, rather than the true capabilities of the A6M. The Americans interpreted the testimony to mean the new fighter lacked manoeuvrability.[11] The underestimation of the A6M seems like a minor error when viewed in isolation. Indeed, American pilots quickly gained an understanding of the fighter from their first combat encounters.[12] However, it was only a symptom of a much broader issue. Evidence that the Japanese had achieved rough technological parity with the United States was belittled or ignored. Individual Japanese aircraft may have been better or worse than foreign counterparts for their intended roles, but American assessments assumed a clear and decisive technological advantage where none existed. Nor did Japanese technological innovation stop with the attack on Pearl Harbor. Both air services introduced aircraft, such as the Nakajima Ki-84 Fighter (Hayate/‘Frank’), that matched some of the best American designs throughout the war.[13] The problem was not that leading-edge Japanese aircraft designs were worse than their American counterparts, but that they never were able to replace their ageing predecessors in sufficient numbers to matter.

The Americans dismissed not just Japanese innovation, but its personnel and tactics. American views of Japanese personnel became increasingly negative after the start of the war in China. Assessments of Japanese factory workers and mechanics significantly reduced in frequency and classified reporting on aircrews indicated that they were of poor to mediocre quality.[14] American observers also continued to emphasize Japan’s lack of pilot reserves and training facilities.[15] Popular literature took a firm stand on Japanese personnel and often relied heavily on racism and national characteristics. One such work listed a number of Japanese racial defects, and summarised them as ‘daring but incompetent aviators.’[16] Classified sources never degraded into this kind of drivel, despite American intelligence shortcomings concerning Japanese tactics and technology.

Captured_Aichi_B7A2_on_ground
A captured Imperial Japanese Navy Aichi B7A2 ‘Grace’, c. 1945. This was one of many capable indigenous aircraft introduced by the Japanese air services during the Pacific War. (Source: Wikimedia)

Surprisingly little reporting discussed Japanese aerial performance in China, and reports that did provide a more balanced, and accurate, assessment of Japanese capabilities.[17] Occasionally, Chinese pilots were interviewed on their combat experience against the Japanese. One report from September 1940 concluded that dive bombing by the IJAAS and IJNAS was ‘very poor,’ while horizontal bombing had ‘improved tremendously.’ Discipline among IJNAS twin-engine bombers was rated ‘excellent,’ and the carrier air groups were given particularly high praise. The most important piece of information provided by Chinese pilots was that the Japanese sent fighter escorts with their bombers whenever possible.[18] However, given the mixed quality of the Republic of China Air Force, their views concerning Japanese capabilities were easily dismissed.[19]

The American underestimation of the Japanese air services’ personnel, tactics, and technology from 1937-41 contributed to, though by no means caused, the early defeats in the Pacific War. However, Japan’s inability to rectify the fundamental problems within its air services and aviation industry crippled its air power as the war progressed, just as American observers had predicted. The accurate assessment that Japan could not win a prolonged war of attrition in the air against the United States was what mattered most. However, the errors in assessing Japanese tactics and technology caused serious problems over the short term. In their haste to predict the setting of the Sun, the Americans failed to appreciate the danger of its rise.

Justin Pyke obtained his MA in Military and Intelligence History from the University of Calgary in 2016. His main research interests include the Asia-Pacific War, military and politics of Imperial Japan, and the development of air and naval power in the inter-war period. He can be found on Twitter at @CBI_PTO_History.

Header Image: A Mitsubishi A6M2 ‘Zero’/‘Zeke’ at the US National Advisory Committee for Aeronautics Langley Research Center, Virginia on 8 March 1943. On 4 June 1942, a Japanese task force launched a strike against Dutch Harbor, Alaska from the aircraft carriers Ryujo and Junyo. Petty Officer Tadayoshi Koga was flying an A6M2 from the Ryujo. On the way back to his carrier, he discovered of bullets had pierced his fuel tanks and he headed for an emergency landing on Akutan Island. However, the plane flipped over on its back during the landing, and Koga was killed. The A6M itself was only slightly damaged. A Japanese submarine failed to locate Koga or his plane, but five weeks later an American naval scouting party found the Japanese fighter. The A6M2 was salvaged and shipped back to the USA where it was repaired, and went through an exhaustive series of tests in order to gain information about its strengths and weaknesses. (Source: Wikimedia)

[1] A-1-m 15776, Dive Bombing in the Japanese Aviation, July 27, 1938, Naval Attaché Reports, 1886-1939, Box 68, RG 38, NA; Japanese Naval Activities in China, July 29, 1940, Naval Attaché Records, 1939-1941, 1940 File 59-124, RG 38, NA; Comments on Naval Aviation by Japanese Naval Aviators, August 23, 1941, Naval Attaché Records, 1939-1941, 1941 File 62, RG 38, NA.

[2] Expansion of Aircraft Manufacturing Industry, July 21, 1937, Selected Naval Attaché Reports Relating to the World Crisis, 1937-1943, Roll 2, RG 38, NA, p. 1.

[3] The Aircraft Industry in Japan, August 5, 1939, Naval Attaché Records, 1939-1941, 1939 File 165-233, RG 38, NA, pp. 1-2.

[4] Mark R. Peattie, Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 (Annapolis: Naval Institute Press, 2001), p. 100; Erich Pauer, ‘Japan’s technical mobilization in the Second World War,’ in Erich Pauer (ed.), Japan’s War Economy (New York, NY: Routledge, 1999), pp. 54-5; Hagiwara Mitsuru, ‘The Japanese Air Campaigns in China, 1937-1945,’ in Mark Peattie, Edward Drea, and Hans Van de Ven (eds.), The Battle for China: Essays on the Military History of the Sino-Japanese War of 1937-1945 (Stanford, CA: Stanford University Press, 2011), p. 243; Jonathan B. Parshall and Anthony P. Tully, Shattered Sword: The Untold Story of the Battle of Midway (Washington D.C.: Potomac Books, 2005), p. 89; Eric M. Bergerud, Fire in the Sky: The Air War in the South Pacific (New York: Basic Books, 2009), p. 21, 46; Sakai Saburo, Martin Caidin, and Fred Saito, Samurai! (Annapolis: Naval Institute Press, 1991), p. 242.

[5] Greg Kennedy, ‘Anglo-American Strategic Relations and Intelligence Assessments of Japanese Air Power, 1934-1941,’ The Journal of Military History, 74:3 (2010), p. 772.

[6] William M. Leary, ‘Assessing the Japanese Threat: Air Intelligence Prior to Pearl Harbor,’ Aerospace Historian, 34:4 (1987), p. 274; 2085-947, The Capabilities of Japan in Military Aviation, June 23, 1939, US Military Intelligence Reports, Japan, 1918-1941, Reel 31, University Press of America, p. 1.

[7] Airplane Characteristics – Mitsubishi Type Zero Fighter, November 9, 1940, Naval Attaché Records, 1939-1941, 1940 File 125-202, RG 38, NA; New Dive Bomber in Production, August 2, 1940, Naval Attaché Records, 1939-1941, 1940 File 59-124, RG 38, NA.

[8] New Types of Aircraft, July 17, 1939, Naval Attaché Records, 1939-1941, 1939 File 89-164, RG 38, NA; Type 97 Torpedo-Bomber, November 16, 1939, Naval Attaché Records, 1939-1941, 1939 File 234-281, RG 38, NA; Specifications of Japanese Naval Bomber, Model 97, June 4, 1940, Naval Attaché Records, 1939-1941, 1940 File 59-124, RG 38, NA.

[9] Richard M. Bueschel, Mitsubishi/Nakajima G3M1/2/3 96 Rikko L3Y1/2 In Japanese Naval Air Service (Atglen: Schiffer Publishing, 1997), p. 20; Description of Navy Heavy Bomber, Type 96, July 26, 1939, Naval Attaché Records, 1939-1941, 1939 File 165-233, RG 38, NA; René J. Francillon, Japanese Aircraft of the Pacific War, Second Edition (London: Putnam Aeronautical Books, 1979), p. 350.

[10] Thomas G. Mahnken, Uncovering Ways of War: U.S. Intelligence and Foreign Military Innovation, 1918-1941 (Ithaca: Cornell University Press, 2002), pp. 79-80; Horikoshi Jiro, Eagles of Mitsubishi: The Story of the Zero Fighter, trans. Shojiro Shindo and Harold N. Wantiez (Seattle: University of Washington Press, 1981), p. 107.

[11] Leary, ‘Assessing the Japanese Threat,’ pp. 275-76; Horikoshi, Eagles of Mitsubishi, p. 85; John B. Lundstrom, The First Team: Pacific Naval Air Combat from Pearl Harbor to Midway (Annapolis: Naval Institute Press, 2005), p. 486; Roger Letourneau and Dennis Letourneau, Operation KE: The Cactus Air Force and the Japanese Withdrawal from Guadalcanal (Annapolis: Naval Institute Press, 2012), p. 13; Sakai et.al., Samurai, p. 83.

[12] John B. Lundstrom, The First Team and the Guadalcanal Campaign: Naval Fighter Combat from August to November 1942 (Annapolis: Naval Institute Press, 2005), pp. 535-36.

[13] See: Francillon, Japanese Aircraft of the Pacific War; Richard M. Bueschel, Nakajima Ki.84a/b Hayate in Japanese Army Air Force Service (Canterbury: Osprey Publishing, 1971).

[14] Notes on Japanese Naval Aviation, August 4, 1939, Naval Attaché Records, 1939-1941, 1939 File 165-233, RG 38, NA; Dropping of Aircraft Torpedoes by Japanese Naval Aircraft, September 26, 1939, Naval Attaché Records, 1939-1941, 1939 File 165-233, RG 38, NA; A-1-m 15776, Aerial Operations, August 2, 1940, Naval Attaché Reports, 1886-1939, Box 68, RG 38, NA; 2085-956, Handbook on the Air Services of Japan, September 27, 1940, US Military Intelligence Reports, Japan, 1918-1941, Reel 31, University Press of America, p. 36, 79.

[15] 2085-908, Military Aviation – General, July 29, 1937, US Military Intelligence Reports, Japan, 1918-1941, Reel 30, University Press of America, p. 3; W.D. Puleston, The Armed Forces of the Pacific: A Comparison of the Military and Naval Power of the United States and Japan (New Haven: Yale University Press, 1941), p. 231.

[16] Fletcher Pratt, Sea Power and Today’s War (New York: Harrison-Hilton Books, 1939), pp. 177-78.

[17] 2085-947, The Capabilities of Japan in Military Aviation, pp. 1-3.

[18] Comment on Japanese Air Force by Chinese Aviators, September 17, 1940, Naval Attaché Records, 1939-1941, 1940 File 125-202, RG 38, NA; Peattie, Sunburst, p. 110, 123.

[19] Peter Harmsen, Shanghai 1937: Stalingrad on the Yangtze (Havertown: Casemate Publishers, 2013), p. 30.

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 2 – 1930-1937

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 2 – 1930-1937

By Justin Pyke

Editorial Note: In the second part of a three-part article, Justin Pyke examines American intelligence assessments of Japanese air power during the inter-war years. This second part examines issues between 1930 and 1937. Part one of this article can be found here.

The early and mid-1930s brought with them a fundamental change in the trajectory of the Japanese air services. Their dependence on foreign technology and assistance began to decrease at the same time American intelligence assessments began to drop noticeably in overall quality. This decline stemmed partly from the dramatic improvement of Japanese information security and the increasing influence of preconceived notions of Japanese unoriginality. Observations concerning the Japanese aviation industry and the broad strategic value of air power remained consistent and accurate, while opinions of Japanese personnel became increasingly contradictory.

Nakajima_Ki-27_at_Hamamatsu
A Nakajima Ki-27 ‘Nate’ fighter aircraft. (Source: Wikimedia)

Western observers were forced to rely increasingly on open sources in place of the informative avenues that they had used previously. The Japanese press reported generally on the air services, and the frequency of reports that paraphrased such news stories gradually increased and replaced the detailed assessments derived from other sources.[1] The amount of information gathered through tours of air stations declined dramatically from 1930-37.[2] Additionally, Western aviation experts and military officers were treated increasingly like spies.[3] The Americans still were able to gather much intelligence regarding strategic and industrial issues, but nothing provided the kind of detailed tactical and technical information that they had grown accustomed to having during the 1920s.

The assessments that came out of Japan from 1930 to mid-1937 continued to accurately track the rapid expansion of the air services, along with the problems that constantly plagued the aviation industry. A June 1930 report contained comprehensive details concerning aircraft production across the dozens of factories that had sprung up in the country. For example, the Kawasaki Dockyard Company in Kobe possessed approximately 200 machine tools in its aircraft and engine factory, almost all of American manufacture.[4] The Japanese had relied heavily on the importation of foreign machine tools during the 1920s and did so even more as the industry expanded. Despite the continuing weakness of the Japanese aviation industry, the author of another report was surprised at the ‘remarkable strides’ that the Japanese Army (IJA) and Navy (IJN) had taken during the previous year, both in quality and quantity of production.[5] Strategy drove these strides. The IJN wished to use air power to overcome the disadvantage in the surface fleet institutionalised by the Washington and London naval arms limitation treaties, and the Imperial Japanese Army Air Service would undergo a similar expansion following the annexation of Manchuria and the 1932 Shanghai Incident.[6]

Foreign observers closely followed Japan’s increased efforts to expand the air services. In 1934, the Soviet State Military Publishing Bureau published a book on the Japanese air services written by D. Streshnevsky.[7] His views on the quality of Japanese industry roughly coincided with those of the Americans. The book listed all the aviation-related factories in Japan and noted that almost every single one had been enlarged, reconstructed, or both. Despite these strides, the aviation industry still depended on imports. Fuel was the most critical shortage, due to Japan’s complete lack of indigenous sources.[8] Such discussions of strategic resources and industrial capability were a staple of intelligence assessments of Japanese aviation, justifiably.[9] In 1936, the American military attaché provided an excellent summary of the strategic and industrial elements of Japanese air power. He noted aircraft manufacturing, which already struggled with a lack of skilled workers, would be hindered even more after the outbreak of hostilities due to the need for expanded production while making use of the same limited pool of the workforce. Additionally, factories could easily be deprived of the raw materials needed to manufacture aircraft of quality and quantity.[10] Another report noted the slow rate of aircraft production meant that Japan was unable to maintain a sufficient aircraft reserve:

planes designated as ‘reserve planes’ are used as much as those in service, and the number may vary from none at all to a disproportionate percentage, especially where units are being equipped with new models.[11]

Overall, reports stressed that Japanese industrial practices were rapidly improving, but still struggled with many inherent weaknesses, such as a reliance on foreign techniques and a shortage of skilled labour, raw resources, and machine tools.

G3M_Type_96_Attack_Bomber_Nell_G3M-24s
An Imperial Japanese Navy’s G3M from Kisarazu Air Group over Sun Yat-sen Mausoleum, Nanking, 1938. This bomber entered service in 1936. (Source: Wikimedia)

Appraisals of Japanese technological progress began to slip in quality during the early and mid-1930s. The preconception that the Japanese were incapable of extensive technical innovation in aviation, which had been true during the 1920s, began to mask the Japanese progress in the area from the early 1930s. It is telling that the translation of Streshnevsky’s work was the only report from the American naval attaché’s office that emphasised Japan’s growing inventive capabilities.[12] Mr Parker of the Bristol Company expressed the typical Western view when he described the Japanese as ‘notorious copyists.’[13] Instead, by 1930 the Japanese were modifying foreign designs to fit their own needs rather than simply copying them wholesale, and an increasing number of designs were entirely of Japanese origin. Several capable indigenous aircraft were designed or entered service from 1933-37, such as the G3M Land-Based Attack Aircraft (‘Nell’), and combined to bring the Japanese air services up to rough technological parity with the West by the late 1930s.[14] By the outbreak of the Second Sino-Japanese War in July 1937, the Japanese had achieved independence in the field of aviation design and manufacturing, something that went unnoticed by American observers.

American assessments of the quality of Japanese pilots, mechanics, and workers were increasingly varied and contradictory. Philip G. Lucas of the Hawker Company stated that the Japanese were ‘competent’ pilots who should not be underrated, implying that the common views held in the United States and Great Britain were inaccurate.[15] Parker and Mr Burgoine of the Bristol Company both agreed that the Japanese were ‘excellent’ fliers, but exhibited a lack of initiative and originality in their flights.[16] Two foreign air force pilots, one British and one German, were given increasingly rare opportunities to witness Japanese pilots in flight while they toured IJA and IJN air stations in early 1935. They both concluded the Japanese were ‘good’ pilots, but the Englishman noted that the Japanese were more ‘conservative’ in their manoeuvring.[17] Streshnevsky’s analysis of Japanese air performance over Shanghai in 1932 left a poor impression. Japanese bombing was ineffectual because of poorly trained pilots and insufficient bomb loads.[18] While reports on aircrew quality were contradictory, American observers continued to accurately note that Japan lacked the depth of aircrew reserves to keep up with the rate of attrition in a high-intensity air war.[19]

Americans assessed Japanese mechanics and workers much as they did their flying compatriots. Mr R. Moffett of the Wright Aeronautical Corporation condemned all the Japanese engineers, mechanics, and workers with whom he worked. Engine mechanics, ‘lamentably poor’ when tasked with correcting minor difficulties with auxiliary equipment, had to be shown the exact detailed procedure to follow. Enlisted men appeared ‘stupid.’ Moffett concluded that the Japanese ‘are striving far beyond their capabilities in the engine field.’[20] Other Western aviation representatives had kinder words for Japanese personnel. Lucas described the Japanese mechanics whom he met as ‘extremely intelligent’ and rated the overall quality of Imperial Japanese Navy Air Service maintenance personnel as ‘very high.’[21] Burgoine and Parker believed that the Japanese could learn rapidly through experience, and thought the mechanics in the aviation industry well-trained and ‘excellent,’ but lacking experience with machine tools.[22]

The American intelligence assessments of Japanese air power from 1930 to mid-1937 remained excellent regarding industrial and strategic issues but were noticeably less accurate regarding technology and tactics. Japanese military aviation had been an open door for intelligence gathering in the 1920s, but the opening gradually narrowed through the early 1930s and slammed shut with the start of the war in China in 1937. The preconception of Japanese unoriginality, particularly regarding aircraft design, became increasingly influential during the 1930s at a time when Japan was moving away from its foreign dependence. Meanwhile, the opinions concerning the quality of Japanese air and ground crews were diverse, varying wildly from praise to derision and everything in between. The lack of a clear and consistent snapshot of Japanese personnel became a major problem in the late 1930s, as did the assumption that the Japanese could not innovate in the aviation sphere.

Justin Pyke obtained his MA in Military and Intelligence History from the University of Calgary in 2016. His main research interests include the Asia-Pacific War, military and politics of Imperial Japan, and the development of air and naval power in the inter-war period. He can be found on Twitter at @CBI_PTO_History.

Header Image: Nakajima Ki-27 at Nomonhan during the Battle of Khalkhin Gol, c. 1939. This indigenous IJAAS fighter entered service in 1937. (Source: Wikimedia)

[1] E-8-a 21984, Japanese Army desires for Unification of Army-Navy Air Service Opposed by Navy, March 20, 1936, Naval Attaché Reports, 1886-1939, Box 732, RG 38, NA.

[2] A-1-l 19973, Tateyama Naval Air Station, December 4 1930, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, January 30 1932, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 4 1933, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 31 1935, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA; A-1-l 19973, Tateyama Naval Air Station, December 24 1936, Naval Attaché Reports, 1886-1939, Box 64, RG 38, NA.

[3] 2085-810, Military Aviation – General: Attachment of British Officer to the 4th Air Regt., February 10 1937, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, p. 2, 15; A-1-a 21684, British Estimate of Japanese Aviation, Continued, May 1 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, 1; A-1-a 21684, British Estimate of Japanese Aviation, February 11 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, p. 2; A-1-a 21684,Visit to Japan of Mr Victor E. Bertrandias of the Douglas Aircraft Company, February 16 1937, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA, pp. 1-2.

[4] 2085-680, Aircraft Factories, June 8, 1930, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, p. 4.

[5] 2085-844, Aircraft Building of the Army & Navy during 1931, March 6, 1932, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, p. 1.

[6] Mark R. Peattie, Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 (Annapolis: Naval Institute Press, 2001), p. 27; Yoichi Hirama, ‘Japanese Naval Preparations for World War II,’ Naval War College Review, 44:2 (1991), p. 69; René J. Francillon, Japanese Aircraft of the Pacific War, Second Edition (London: Putnam Aeronautical Books, 1979), p. 31. For further details on the interwar naval arms limitation treaties, see: Erik Goldstein and John H. Maurer (eds.), The Washington Naval Conference, 1921-22: Naval Rivalry, East Asian Stability and the Road to Pearl Harbor (London: Frank Cass, 1994); John H. Maurer and Christopher M. Bell (eds.), At the Crossroads between Peace and War: The London Naval Conference of 1930 (Annapolis: Naval Institute Press, 2014).

[7] A-1-a 21973, Development of the Japanese Air Fleet, March 5, 1936, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA; A-1-a 21973, Japanese Naval Aviation, June 1, 1936, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA.

[8] A-1-a 21973, Development of the Japanese Air Fleet, 6-12.

[9] A-1-a 21684, British Estimate of Japanese Aviation; A-1-a 21684, British Estimate of Japanese Aviation, Continued; 2085-812, Aircraft Production – Non-Governmental. Mitsubishi Heavy Industries Company, Ltd. Nagoya Aircraft Works, June 7, 1937, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America; 2085-885, Air Information, April 28, 1934, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America; 2085-687, Reply to Evaluation of Reports, October 23, 1936, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America.

[10] 2085-687, Reply to Evaluation of Reports, October 23, 1936, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, p. 1.

[11] 2085-810, Military Aviation – General, p. 1.

[12] A-1-a 21973, Japanese Naval Aviation, p. 5.

[13] A-1-a 21684, British Estimate of Japanese Aviation, p. 4.

[14] Mikesh and Abe, Japanese Aircraft, p. 45; Peattie, Sunburst, p. 86, 89. Also see: Francillon, Japanese Aircraft of the Pacific War.

[15] A-1-a 21684, British Estimate of Japanese Aviation, Continued, p. 2.

[16] A-1-a 21684, British Estimate of Japanese Aviation, p. 4.

[17] A-1-a 21684, Foreign Opinions Regarding Japanese Naval and Military Aviation, February 21, 1935, Naval Attaché Reports, 1886-1939, Box 10, RG 38, NA.

[18] A-1-m 15776, Fighting Experience of the Japanese Military Air Forces, March 17, 1936, Naval Attaché Reports, 1886-1939, Box 68, RG 38, NA, 6.

[19] 2085-687, Reply to Evaluation of Reports, p. 2.

[20] A-1-a 21684, Visit to Japan of American Aircraft Representative, p. 1.

[21] A-1-a 21684, British Estimate of Japanese Aviation, Continued, pp. 1-2.

[22] A-1-a 21684, British Estimate of Japanese Aviation, p. 4.

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 1 – The 1920s

Blinded by the Rising Sun? American Intelligence Assessments of Japanese Air Power, 1920-41: Part 1 – The 1920s

By Justin Pyke

Editorial Note: In the first of a three-part article, Justin Pyke examines American intelligence assessments of Japanese air power during the inter-war years. This first part examines issues in the 1920s.

In December 1941 Japan launched a campaign of rapid conquest against British, American, and Dutch possessions throughout the Asia-Pacific region. The Imperial Japanese Army Air Service (IJAAS) and Imperial Japanese Navy Air Service (IJNAS) proved critical to the success of these early campaigns. Although American authorities identified Japan as a primary rival after 1918 and focused most of their intelligence gathering efforts on the East Asian nation, they failed to appreciate the threat posed by Japanese air power in 1941. This failure was not as simplistic as the old historiography portrays.[1] Instead, intelligence assessments of Japanese air power passed through three distinct phases. During the 1920s, American observers maintained an accurate picture of Japanese capabilities. Japan was largely an open society, and its air services depended on Western assistance, meaning the Americans were able to track major developments. The early and mid-1930s was a transition period from the openness of the 1920s to the extreme secrecy that characterised the period from 1937 onward. With the start of the war in China, the Americans were almost completely in the dark regarding assessments of the Japanese air services’ technology, tactics, and personnel. One thing that remained consistent from 1920-41 was American observers accurately assessed the strategic and industrial limits of Japan’s air power. Success with these higher level assessments ultimately mattered more than the mistakes made assessing technology and tactics.

SempillMission
Captain Sempill showing a Gloster Sparrowhawk to Admiral Tōgō Heihachiro, 1921. (Source: Wikimedia)

Throughout the 1920s, Japan worked rapidly to catch up with the developments of Western powers in the field of military aviation. During this period, American intelligence assessments remained accurate at all levels, from personnel, tactics, and technology to industry and the scarcity of raw resources. American observers quickly identified Japan’s heavy reliance on foreign assistance and the weakness of its aviation industry, while the quality and quantity of Japanese aviation personnel and aircraft were carefully tracked. As throughout the entire inter-war period, the assessments primarily addressed Japan’s ability to wage a protracted war of attrition in the air, rather than to focus on tactical and technical capability.

The accuracy of American assessments in the 1920s was due in large part to openness within Japan. Letters were constantly exchanged between the American naval attaché and the Japanese Navy Ministry. The letters requested information about the IJNAS, such as its organisation, the numbers of available aircraft, and the number of existing and planned naval air stations. The Navy Ministry answered these letters in full.[2] The ease with which the naval attaché obtained large amounts of information through direct communication with the Navy Ministry was remarkable, but the openness of the Japanese was not limited to such communication. Tours of aircraft manufacturing facilities and air stations were also open and casual. The Americans were not rushed through important areas. The level of detail in an extensive report on Japanese aircraft factories from 1925 was typical and revealed lax Japanese information security. Minor technical details and factory layouts were abundantly described throughout the report, revealing the high level of access Americans had at the facilities. Japanese workmen and designers were extremely forthcoming when asked direct questions about their work.[3]

Japan’s reliance on foreign assistance allowed the Americans to keep pace with its technological and industrial advances. A report in 1924 stated that Japan always sought out the best foreign designed aircraft that it could purchase, and copied these models, along with the means to produce them. The air services were also modelled after what the Japanese thought was the most advanced foreign air forces.[4] For example, the IJNAS relied on British assistance regarding industrial practices, aviation technology, personnel training, and tactics.[5] The American naval attaché constantly emphasised the Japanese inability to design and build aircraft without extensive foreign aid. After inspecting the aircraft factories, he concluded that they had yet to produce any indigenously designed aircraft or engines ‘of any value whatsoever.’[6] A general summary from 1927 noted that all Japanese aircraft were of foreign design and that these aircraft were underpowered and inferior to contemporary American designs.[7] This claim was an overstatement, but the number of indigenous Japanese military designs remained very small throughout the 1920s.[8] The motif of Japanese unoriginality would persist through to the beginning of the Pacific War, long after it had ceased to be true. In the 1920s, however, Japan did seek to develop its air power by following in the footsteps of the world leaders.

The inferior production methods of Japan’s major aircraft manufacturers were also highlighted. One such report noted that most of the machine tools in the factories were of American manufacture and the machine shops themselves were crowded, which led to inefficiency within the production process. Production was prolonged, particularly when a factory was ordered to manufacture new types of aircraft. During this process, foreign workmen were always employed to ensure a smoother transition.[9] The Japanese aviation industry’s inability to rapidly turn existing factories over to produce new models of aircraft persisted into the Pacific War. It undermined Japan’s ability to keep pace both qualitatively and quantitatively with their Western foes. For example, the J2M Navy Interceptor Fighter (Raiden/‘Jack’) first flew nearly three months ahead of the F6F Hellcat prototype’s first flight. Despite this, the first production Hellcat was completed in the same month that the J2M had only just been accepted for serial production. Six months later only 14 J2Ms had been delivered at a time when Hellcats leapt off the American production lines.[10]

The opinion of Japanese personnel was generally low but remained balanced. A 1926 memorandum held Japanese airmen and officers in high regard, referring to them as ‘well disciplined.’ Most pilots were described as ‘good,’ while the work of the mechanics was deemed ‘most praiseworthy.’[11] The naval attaché’s assessments of Japanese pilots were more critical. One report concluded that the Japanese have a ‘fair ability’ as pilots, but rated them poorly in all around efficiency.[12] The British aviators who had trained the IJNAS in the early 1920s informed the Americans of their low opinion of Japanese personnel, and this view was shared by Colonel Jacques-Paul Faure, head of the French Military Aviation Mission to Japan that had trained the IJAAS’ pilots.[13] A major 1928 report on Japanese aviation viewed mechanics within the Japanese air services as poor, although civilians brought in to help the military were good.[14] Conspicuous by its absence was any notion of the inferiority of the Japanese race despite the criticism levelled against Japanese personnel.

FrenchMilitaryMissionToJapan
The French Military Mission to Japan, 1918-1919 (Source: Wikimedia)

A handful of reports did, however, attribute personnel deficiencies to the national characteristics, or national stereotypes, of the Japanese people. One assessment stated that:

[t]he Japanese is not a natural flyer and rarely loves flying for its own sake. Neither is he a natural mechanic, nor has he any tradition of trained mechanics behind him.[15]

While it is easy to dismiss this statement as racist or irrational, it did contain some truth. The Japanese air services had a chronic shortage of trained mechanics, partly because Japan was not a fully industrialised nation like the United States or Great Britain. The Japanese economy, despite massive leaps since the Meiji Restoration, continued to operate ‘with one foot in the nineteenth century.’[16] Once again, the quality of Japanese pilots was called into question, but the report concluded that if American pilots were considered ‘very good,’ the Japanese were rated ‘good.’[17] This statement made it clear that the Japanese were inferior to their western counterparts, but it was hardly irrational or unfair.

The most noteworthy weaknesses that the Americans identified regarding Japanese aviation personnel were the lack of pilot training and reserves. In an information bulletin detailing the Japanese Diet’s 1924 budget for naval aviation, the naval attaché noted that the IJNAS had no reserve personnel at all.[18] Another report stated that ‘there are three schools of aviation, but only one [sic] army flying training school,’ and went on to detail the number of pilots available to Japan.[19] The 1927 general summary of the Japanese air services questioned the flying experience of the officers, and described the flying seen in Japan as ‘characterized by timidity and one could not help but feel that dash and spirit were lacking.’ The report concluded that the IJAAS and IJNAS were at:

[a]n elementary stage of development. None of them are capable of combat with well developed aviation, considering factors other than equipment.[20]

Taken as a whole, American intelligence assessments of Japanese air power during the 1920s were highly accurate from the strategic and industrial spheres down to the tactical and technological level. Lax information security measures within Japan provided American observers with a remarkable level of freedom. American reports assessed the ability of Japan to fight a protracted war in the air, where aircraft production figures, industrial efficiency, innovative aircraft design, strong pilot training programs, and sizeable pilot reserves were critical to achieving success. The correct conclusion was Japan did not yet possess air power that could seriously threaten the Western powers, but this would begin to change in the 1930s.

Justin Pyke obtained his MA in Military and Intelligence History from the University of Calgary in 2016. His main research interests include the Asia-Pacific War, military and politics of Imperial Japan, and the development of air and naval power in the inter-war period. He can be found on Twitter at @CBI_PTO_History.

Header Image: A Nakajima A2N carrier borne fighter that first flew at the end of the 1920s. (Source: Wikimedia)

[1] For examples of the old view regarding American intelligence assessments of Japan, see: John W. Dower, War without Mercy: Race and Power in the Pacific War (New York: Pantheon Books, 1986); David Kahn, ‘United States Views of Germany and Japan in 1941,’ in Ernest R. May (ed.), Knowing One’s Enemies: Intelligence Assessment before the Two World Wars (Princeton: Princeton University Press, 1986).

[2] A-1-u 17242, Letter to Captain K. Terashima, I.J.N., January 27 1925, Naval Attaché Reports, 1886-1939, Box 142, Record Group [RG] 38, National Archives and Records Administration [NA], Washington, D.C.; A-1-u 17242, Information on Air Services, March 5 1926, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA; A-1-u 17242, Letter to Mr McClaran, February 10 1925, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA.

[3] A-1-u 17242, Visit to Aircraft Factories, May 15, 1925, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA.

[4] 2085-630, Extracts from Report of Inspection of United States Possessions in the Pacific and Java, Singapore, India, Siam, China, & Japan, October 24, 1924, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, 1.

[5] Mark R. Peattie, Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 (Annapolis: Naval Institute Press, 2001), pp. 17-20; Jonathan Parkinson, ‘HIJMS Wakamiya and the Early Development of Japanese Naval Air Power,’ The Mariner’s Mirror, 99:3 (2013), pp. 318-321. Also see: John Ferris, ‘A British ‘Unofficial’ Aviation Mission and Japanese Naval Developments, 1919-1929,’ Journal of Strategic Studies, 5:3 (1982), pp. 416-39.

[6] A-1-u 17242, Japanese Air Strength, May 5, 1925, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA, 3.

[7] 2085-663, General Summary Japanese Air Service, June 1, 1927, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, 8.

[8] See: Robert C. Mikesh and Shorzoe Abe, Japanese Aircraft, 1910-1941 (Annapolis: Naval Institute Press, 1990).

[9] A-1-u 17242, Visit to Aircraft Factories, 1, 8.

[10] Fighter Combat Comparisons No. 1: Grumman F6F-5 Hellcat vs. Mitsubishi J2M3 Model 21 Raiden (‘Jack’) (Teaneck: Tacitus Publications, 1989), p. 13.

[11] 2085-647, Memorandum for Major Baldwin, September 30, 1926, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America, 3, 6.

[12] A-1-u 17242, Japanese Air Strength, 3.

[13] Thomas G. Mahnken, Uncovering Ways of War: U.S. Intelligence and Foreign Military Innovation, 1918-1941 (Ithaca: Cornell University Press, 2002), p. 73; A-1-u 17242, Aviation, July 21, 1925, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA, 3.

[14] 2085-784, Report of Major W. B. Duty, September 20, 1928, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, 83.

[15] 2085-748, Japanese Aviation: Army, Navy, Civil, July 20, 1927, US Military Intelligence Reports, Japan, 1918-1941, Reel 29, University Press of America, 2.

[16] Eric M. Bergerud, Fire in the Sky: The Air War in the South Pacific (New York: Basic Books, 2009), p. 17.

[17] 2085-748, Japanese Aviation: Army, Navy, Civil, 2.

[18] A-1-u 17242, Data for Congressional Hearing; Additional Detailed Information on Air Services, February 9, 1925, Naval Attaché Reports, 1886-1939, Box 142, RG 38, NA, 2.

[19] 2085-719, Information as to Japanese Aviation, February 9, 1927, US Military Intelligence Reports, Japan, 1918-1941, Reel 28, University Press of America.

[20] 2085-663, General Summary Japanese Air Service, 3, 7.