The Elusive Enemy: U.S. Naval Intelligence and the Imperial Japanese Fleet

By Douglas Ford

The Elusive Enemy explores the evolution of U.S. intelligence concerning the combat capabilities of the Imperial Japanese Navy and its air arm during the interwar period and the Pacific War. Ford contends that the US Navy could not accurately determine the fighting efficiency of Japan’s forces until it engaged them in actual battle conditions over an extended period. As the conflict progressed, the Americans were able to rely on a growing array of intelligence material, including POWs, captured documents, and specimens of captured enemy weapons. These sources often revealed valuable information on the characteristics of Japanese equipment, as well as some of the ideas and doctrines which governed how they carried out their operations. First-hand observations of the Japanese navy’s performance in battle were the most frequently used source of intelligence which enabled the US Navy to develop a more informed assessment of its opponent. Ship crews, along with US aviators, were tasked to collect information by making a thorough observation of how the Japanese fought. Action reports described how the Imperial fleet demonstrated a number of weaknesses, the most important of which was a shortage of modern equipment and, after 1942, diminished air power. Yet, he demonstrates how the Japanese remained a resilient enemy who could be defeated only when the Americans deployed sufficient equipment and used it in an appropriate manner. The Office of Naval Intelligence, as well as the intelligence services operating in the Pacific theater, thus had to assess a wide array of conflicting characteristics, and provide a balanced evaluation concerning the strengths and weaknesses of the Imperial navy. At the same time, a large part of the intelligence analysis was undertaken by commanders in the Pacific Fleet. Naval personnel and aircrews assessed the information gained through encounters with the enemy so that they could develop a set of methods whereby US forces were able defeat the Japanese without incurring excessive casualties and losses. The intelligence services, in turn, played an important role in disseminating the information on the most efficient tactics and weapons that could be used to defeat the Imperial Fleet. The Elusive Enemy aims to explain how American perceptions concerning the Japanese navy evolved during the conflict, with a particular focus on the role of intelligence. It also seeks to introduce a new perspective on the question as to why the U.S. Navy carried out its campaigns during the Pacific War in the manner that it did.

• Language: English
• Publisher: Naval Institute Press
• Release date: Oct 15, 2011
• ISBN: 9781612510651

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Table of Contents

Title Page

Acknowledgments

Abbreviations

Introduction

Chapter 1 - Gauging an Untested Opponent

Importance of Japan as an Intelligence Target

Nature of the Intelligence Received

Intelligence Assessments of the IJN

A Formidable Adversary? The Navy Establishment s View of the IJN

Conclusion

Chapter 2 - Dismantling the Lesser Foe and Superior Enemy Images

Lessons of Defeat, December 1941 to Early 1942

The Turn of the Tide, June 1942 to Spring 1943

Lessons of Limited Victories: Encounters with the IJN’s Fleet

Encounters with the IJN Air Arm

Conclusion

Chapter 3 - The Elusive Enemy

Evolution of the U.S. Navy s Intelligence Capabilities

Intelligence on the IJN’s Numerical - Strength and Operational Plans

Lessons of Combat Experience

Implications for the U.S. Navy s Operations

Conclusion

Chapter 4 - The Underdog in the Air War, Yet a Resourceful Opponent

Intelligence on the IJNAF’s Numerical Strength

Development of the U.S. Navy s Air Intelligence Capabilities

Battle Lessons

Conclusion

Chapter 5 - Knowledge of the Enemy Applied

Evolution of the U.S. Navy s Antiaircraft Defense Capabilities

Fighter Defense

The Kamikaze Challenge

Conclusion

Conclusion

Notes

Bibliography

Index

About the Author

Copyright Page

Acknowledgments

This book is largely a sequel to my first published monograph on British intelligence and the campaigns against Japan on the Southeast Asia front, which admittedly focused on what was a peripheral, albeit interesting, theater of World War II. The idea of producing a work that covered the much wider canvas of American intelligence and the Imperial Japanese armed forces in the Pacific Ocean areas dawned on me toward the closing phases of my tenure as a graduate student, when most aspiring scholars begin to contemplate how they envision their careers as academic researchers.

The completion of this book would not have been possible without the generous support provided by my employers at the University of Salford. During the summers of 2005 to 2007, I was able to undertake several trips to the other side of the Atlantic and spend extended lengths of time in the Washington, D.C., area, thanks to the travel allowances that were unquestioningly offered by John Keiger and the European Studies Research Institute. A good part of the finances needed to complete the research for this book were also made available through the University of Salford’s research investment fund. Last but not least, I would like to thank my colleagues for letting me take a six-month sabbatical leave during the early part of 2008. Without being allowed parole from my normal teaching duties, it is most unlikely that the work could have been finished in the time frame that it was completed.

A team of archivists have gone out of their way to assist me in compiling the materials needed for this research project. I thank the staff at the National Archives in College Park. In particular, Patrick Osbourne, along with the lately departed and much missed John Taylor, was invaluable in helping me make sense out of the seemingly endless and indecipherable catalogs of the Navy Department and Office of Naval Intelligence records. The archivists at the U.S. Naval Historical Center were nothing but cooperative in tracking down the documents and private papers in their collections. During my visit to the Naval War College at Newport, Rhode Island, Evelyn Cherpak untiringly retrieved the countless boxes that I ordered on an around-the-clock basis. Last my gratitude also goes to the staff at the manuscripts collection of the Library of Congress, as well as the British National Archives in London. Every effort has been made to ensure that the necessary permissions for quotation of documentary material have been obtained, and I offer my most sincere apologies to anyone whose copyrights I have unknowingly infringed upon.

Portions of this book have already appeared in works published. Many of the documents from the British National Archives have been cited in the monograph Britain’s Secret War against Japan, 1937–45 (2006). A large part of Chapter One has been published as U.S. Naval Intelligence and the Imperial Japanese Fleet during the Washington Treaty Era, c.1922–1936, in Mariner’s Mirror (2007). The sections on Japanese intelligence and strategic culture also appeared in Strategic Culture, Intelligence Assessment, and the Conduct of the Pacific War, 1941–1945: The British-Indian and Imperial Japanese Armies in Comparison, in War in History (2007). Finally, a small part of Chapter One, on American war planning prior to December 1941, was published in Realistic Caution and Ambivalent Optimism: U.S. Intelligence Assessments and War Preparations against Japan, 1918–1941, in Diplomacy and Statecraft (2010).

Among the scholars who have offered priceless advice and ideas that helped me better my understanding of the intricacies of intelligence studies and naval affairs, as well as to follow through with the research and writing phases of this manuscript, I would like to thank Richard Aldrich, Martin Alexander, Antony Best, John Ferris, Eric Grove, Peter Jackson, Ken Kotani, Joe Maiolo, Chris Murphy, Sally Paine, Nick Sarantakes, Len Scott, Alaric Searle, and Larry Valero. The history and security studies team at Salford is simply a wonderful group of friends, and the most congenial colleagues one can hope to work with. Finally, my students, both my former ones at the London School of Economics and Aberystwyth University as well as the current cohort at Salford, have never failed to offer fresh ideas and concepts on how to study the subject areas of military history and intelligence.

This book is dedicated to my family, for their never-ending support of my life ambitions and endless patience at having an academic in their tow.

DOUGLASFORD

MANCHESTER, MAY 2011

Abbreviations

Introduction

More than sixty years have passed since the Pacific War ended, and the U.S. Navy’s experience in fighting the Imperial Japanese Navy (IJN) continues to attract attention from historians. The sustained interest is due to a number of factors. The campaign in the Asia-Pacific theaters constituted one of the first occasions where the participants made extensive use of modern naval technologies, including maritime aviation and the submarine, both of which caused much greater levels of damage than previously available weapons. Personnel from the U.S. and Japanese navies faced what was often a complicated task of figuring out ways to deploy their armaments to neutralize their enemy, while at the same time providing adequate protection for friendly forces.

More significant, the Americans were engaging an opponent whose capabilities they had long tried to assess prior to the conflict, but which they had seriously underestimated. Until the Japanese launched their attack on Pearl Harbor in December 1941, the accepted belief among defense officials was that the IJN had serious weaknesses that prevented it from challenging the U.S. Navy. The destruction that the IJN and its air arm inflicted during the opening stages, including the sinking of a large portion of the U.S. fleet, along with HMS Prince of Wales and Repulse off the coast of Malaya, compelled the Americans to reconsider their views. In order to develop a more realistic evaluation, the U.S. Navy needed to undertake a substantial endeavor to obtain accurate information on its opponent, and study the material in a judicious manner. Naval intelligence played a pivotal role in shaping the conduct of the Pacific War. It helped U.S. ship crews and airmen learn how the IJN was a skillful fighting force that could be overcome only when they developed an effective means of deploying their weapons.

Three conclusions emerge from the work. First, combat experience was the most important source of intelligence that helped the Americans to understand the Japanese. Second, while first-hand encounters were vital, an equally significant catalyst was the naval establishment’s organizational culture, which stated that wars were to be carried out with a good awareness of the enemy’s capabilities. Because strategic plans were based on a premise that fighting the Japanese required U.S. forces to conduct a protracted campaign, intelligence efforts were subsequently geared to evaluate the IJN’s capacity to do likewise. Finally, and directly related, racial perceptions did not play a significant role in shaping American opinions of the Japanese. On one hand, the ethnic divide that separated the belligerents made it difficult to ignore cultural characteristics and their effect on the enemy’s performance. Nevertheless, intelligence staffs, along with naval personnel, realized that they did not have enough information to make an educated assessment. This was in line with the U.S. Navy’s habit of basing its judgments of foreign armed forces on a logical analysis of the available evidence, rather than inferences.

Intelligence Studies and Pacific War Historiography

A large part of the existing literature on the Pacific War tends to overlook the intelligence dimension, mainly because intelligence studies, as an academic discipline, remains in a stage of relative infancy. Until the use of intelligence in warfare became common at the turn of the twentieth century, scholars of military affairs, along with practitioners, made minimal references to the subject. A notable exception was the Chinese theorist Sun Tzu, whose treatise, written around the sixth century BC, affirmed that knowledge of the enemy was an essential requisite for avoiding defeat. Success did not necessarily hinge on the use of weapons, but more on what he described as measurement, or weighing the relative strengths and weaknesses of the opposing sides.¹ Yet until recently the majority of academics held an accepted view that maintained that the study of intelligence was impossible. The notion was not entirely mistaken. Intelligence activities have always been carried out with exceptional secrecy, and those involved hesitate to expose their results, whether successful or otherwise. During the early 1980s, Christopher Andrew and David Dilks described intelligence as the missing dimension of history, because written records available for public inspection were few and far between.²

In subsequent decades, as freedom of information acts enabled governments around the world to release archival materials on intelligence during World War II and, later, the Cold War period, intelligence studies became a growth industry. Today, with the plethora of documentation that is accessible, the assumption that one cannot conduct serious research in the area must be treated with utmost skepticism. Scholars, as well as practitioners, have put forward a number of definitions for the term intelligence, all of which are key to comprehending the nature of its activities. While intelligence constitutes information, it needs to be conceptualized as information that is handled in a certain manner. Intelligence does not necessarily need to be based on confidential sources, nor does it have to be carried out by specialized agencies. ³ Nevertheless, the main functions of the intelligence cycle, namely, the collection, analysis, and distribution of knowledge, along with its implementation into policy, need to be undertaken by state officials, and kept secret so as to prevent the enemy from compromising the success of an organization’s activities.⁴ In reality, the intelligence cycle is not a smoothly integrated process, but a complex web of relations between the producers of intelligence and the policymakers they serve.⁵ The interactions are frequently characterized by uncertainties within both parties on what types of information need to be obtained, as well as disagreements over who should have access to the material. Furthermore, when intelligence organizations are not equipped to handle information, policymakers take on a large part of the tasks, including analysis. Yet the concept of the cycle is useful for viewing intelligence as a series of discrete steps, moving from early decisions concerning data compilation to the ultimate act of using the finished product to inform decision-makers. Of equal importance, intelligence is information geared for a specific purpose. John Ferris describes it as the collection and analysis of information by a power, to enable it to make the maximum use of its resources against potential enemies.⁶ Intelligence helps leaders understand their environment, and can offer hints on how to employ the main instruments of statecraft, namely, diplomacy and armed force, to protect national interests. Among the most popular approaches to intelligence studies are those that treat it as a way of providing new explanations as to why decision-makers have developed their perceptions of world events, and the way in which the perceptions, in turn, have led them to deal with particular crises in the manner that they have.⁷ The best works have examined the relationship between collection and analysis on one hand, and the subsequent influence on the decision-making process on the other hand.

Although intelligence has proven to be an integral component of international conflicts, the scholarship still contains large gaps. Part of the reason is that intelligence archives are not always neatly organized, and hence are harder to navigate in comparison with other primary sources. The root of the problem, however, most likely stems from the fact that historians do not attempt to make use of the evidence that has become available, because they are reluctant to cast off their traditional view that intelligence studies is an esoteric and inaccessible subject area.⁸

This book fills the gap by examining how U.S. intelligence on the IJN developed during the Pacific War and explaining the subsequent influence on the Navy’s conduct of its operations. The semi-official histories on U.S. naval operations during World War II provided detailed accounts of the campaigns in the Pacific theaters.⁹ Attempts have also been made to determine the underlying causes for the U.S. Navy’s performance. The works covering doctrine and technology suggest that the main task was to deploy the Pacific Fleet’s ships and weapons in a manner that worked to overcome the Japanese.¹⁰ The perceptions that U.S. personnel held concerning the IJN, and their views of the obstacles they faced, have been described, but the ways in which the views evolved have not been analyzed in great detail. Likewise, the literature on the key naval battles addresses the lessons learned through encounters with the Japanese navy, but tends not to describe how those lessons influenced the long-term advancement of U.S. fighting methods.¹¹

In explaining the U.S. victory in the Pacific theaters, many authors have highlighted material factors such as economic prowess. John Ellis illustrated how America’s abundant supply of resources and manufacturing plants enabled it to build an overwhelmingly larger quantity of ships, aircraft, and equipment than the Japanese. The outcome thus relied heavily on industrial predominance and the enormous margins of superiority in military hardware that flowed from it.¹² At the same time, a number of historians have argued that the success did not depend solely on resources. Ronald Spector concluded that effective training and strategic planning played an equally important role.¹³ More recently, Richard Overy emphasized how the statistics pointing to matériel do not tell the whole story, and argued that one needs to look at equally important features, including the comparative quality of the weapons, and how well they were used.¹⁴ Industrial productivity made the Allied victory in World War II possible, but did not render it a foregone conclusion. Economic strength had to be harnessed to construct an effective fighting machine, whose performance was not merely determined by quantitative factors, but by a number of intangible aspects, such as doctrine and morale. The hypothesis raises questions as to how other qualitative facets, such as knowledge of the enemy, helped U.S. forces wage a successful campaign. This is not to suggest that intelligence was the primary factor that enabled the Americans to prevail. The best intelligence is impotent unless armed forces have sufficient strength to execute their operations.¹⁵ Nevertheless, when commanders properly utilize intelligence, it acts as a force multiplier that allows for a more efficient and economical deployment of resources. Intelligence helps one identify enemy weaknesses that are open to attack, as well as the strengths one needs to guard against. The U.S. Navy’s engagements against the IJN were no exception to this rule.

The majority of the works that do cover intelligence during the Pacific War focus on the traditional sub-area of signals intelligence (sigint). The literature describes how the Allied intelligence services succeeded in decoding the IJN’s communications, and provided commanders with information that was vital for carrying out their operations.¹⁶ While signals decrypts have proven useful for obtaining statistical data on force dispositions and numerical strengths, they often provide limited information on matters such as fighting methods and the quality of training. The latter are often described as qualitative or non-material features, a knowledge of which is essential in order to engage enemy forces.¹⁷ Indeed, an officer who served extensively in Asia during the interwar period described cryptanalysis as only one part of intelligence.¹⁸ Intelligence staffs need to draw upon an array of evidence, including human agents, documentary sources, and photographic reconnaissance. The particular conditions of wartime also permit the use of material that is not available in times of peace, the most important of which is observations of how enemy forces perform in battle. The term intelligence will encompass the full range of information the U.S. Navy drew upon. To use a term coined by practitioners, this work focuses on all source analysis.¹⁹

While all military organizations need to properly gauge their adversary, the task involves substantial complications. In the early part of the nineteenth century, Carl von Clausewitz described how one of the foremost dilemmas facing any army is that the situation on the battlefield undergoes constant changes. According to Clausewitz, the value of intelligence is at best questionable, and commanders thus have to use their imagination, while relying on boldness and surprise to overcome their opponents.²⁰ In recent decades, scholars have drawn upon numerous historical case studies to lay out the uses and limits of intelligence. One of the most prominent works has been written by Michael Handel, who questioned Clausewitz’s contention that military genius and intuition be used to deal with the unknown, and asserted that all leaders need at least some sort of intelligence to support their estimates.²¹ At the same time, intelligence does not necessarily offer an insight into the enemy’s intentions and capabilities. Much depends on how the material is evaluated, and the analyst’s intellectual capabilities are the key assets needed for a good judgment.²² The harsh reality that befalls any intelligence organization is that data processing remains a human activity, which is frequently prone to error. Analysts need to synthesize a wide pool of information, and make sense out of a world where the strategic and political environment consists of a multitude of unfamiliar elements that are constantly evolving. In addition, when foreign nations keep their activities secret, assessments are by definition based on incomplete knowledge. Intelligence can thus alleviate the element of uncertainty that decision-makers are persistently confronted with, but cannot be realistically expected to remove it.²³ Technological improvements, in the form of more efficient equipment for collecting, collating, and communicating information, do not offer a panacea. On the contrary, the large amounts of intelligence that become available often create a data overload and further confusion.²⁴

Nevertheless, when appraised properly, intelligence does provide a more realistic image than would otherwise be the case. While the battlefield situation may be composed of complex features that preclude a crystal-clear estimate, it does not follow that calculations are futile.²⁵ Furthermore, predicting the behavior of outside parties is problematic, but judgments to the effect that certain courses of action are more or less probable in given circumstances can often be made, and with good accuracy.²⁶ Leaders who use intelligence regularly are also more likely to pursue a policy that is suited for dealing with the situations they face than those who try to manage without it.²⁷ The ideal assessment produces a coherent overall analysis for the policymaker, while at the same time drawing attention to the aspects that remain uncertain.²⁸

Intelligence and the Conduct of the Pacific War: Challenges and Benefits

The U.S. Navy’s intelligence effort during the Pacific War illustrates how evaluating an enemy presents a number of challenges, as well as benefits. The most significant problem stems from the fact that military organizations almost invariably embark on hostilities without fully knowing the elements they have to face, largely because the preceding period of peace provides limited opportunities to obtain information. In comparison to other state institutions, defense establishments contend with a unique dilemma, in that they must prepare for conflicts that may occur at an undetermined point in the future, against an opponent whose fighting potential is uncertain, and in conditions of violence that cannot be simulated in peacetime.²⁹ Yet the preparatory measures taken prior to hostilities have a decisive impact on how armed services perform in wartime conditions. The task becomes more intricate during periods of revolutions in military affairs (RMA), when nations acquire a significantly altered capacity to project their military potential, as a result of various technological, economic, and social changes. The years prior to the Pacific War witnessed a particular type of RMA, where the increased availability of the internal combustion engine, coupled with advances in aircraft technology, led to the development of new weapons systems such as maritime aviation and the submarine. Naval war plans had to be based on the understanding that friendly forces and potential enemies alike had opportunities to devise new ways of fighting. Indeed, one of the key axioms emphasized in Alfred Mahan’s seminal work was that changes in naval technology do not necessarily alter the strategies used to achieve wartime objectives, but they inevitably affect more detailed features such as the tactics for defeating the opponent’s fleet.³⁰ Julian Corbett also described how, throughout the centuries, naval staffs held certain theories on how to conduct operations, often without realizing that the ideas actually influenced their practices.³¹ To provide an obvious example, the types of ships that constitute a fleet are the material expressions of the strategic and tactical ideas that prevail at any given time. When RMAs take place, defense establishments not only need to rethink their perceptions on how to deploy their forces. They must visualize how future wars might transpire, and discern the ways in which the innovations can render those conflicts different from their predecessors.³² Yet the efficacy of the innovations, whether they are taking place at home or abroad, cannot be discovered until they are tested in battle.

To reduce the ambiguities, the defense communities of the Great Powers during the interwar years assigned their intelligence staffs to secure and examine data concerning the combat methods and equipment being developed by their rivals. The experiences of World War I were a helpful benchmark that enabled military officials to calculate the military capabilities of foreign powers.³³ During the conflict, a number of modern armaments made their first appearance in combat, thereby providing some indications on how they might affect the conduct of warfare.

Aside from historical precedents, the manner in which individual armed forces responded to the circumstances facing them was largely influenced by the organizational ethos, or strategic culture, that prevailed in the particular establishment.³⁴ Strategic culture is defined as a distinct and lasting set of behavioral and thought patterns governing the use of force, and it plays a central role in determining how officials assess the external environment and figure out possible responses to the threats with which they contend.³⁵ The notion that cultural factors affect military performance is derived from the premise that human actions are conditioned by the principles that prevail in their environment. Likewise, the policies followed by a particular institution are shaped by the distinct ideas that it holds. In warfare, certain attitudes are more likely to bring success than others. Organizations that show less imagination in peacetime are unlikely to adapt to the actual conditions they have to fight in.³⁶ On the other hand, armed services that seek to develop a knowledgeable assessment of strategic realities have better prospects of overcoming their opponents.³⁷

In determining the foundations of strategic culture, one can examine a number of visible features, including a nation’s geopolitical position, its past experiences with warfare, and the value systems held by its armed services. On the subject of culture and its relation to intelligence, the existing scholarship frequently explains how the functions of an organization, along with the types of information it seeks, are governed by the specific policy priorities of the parent nation.³⁸ Cultural factors also have an effect on the importance that leaders place on creating a realistic view of their adversaries. Less rigorously explored is the interaction between strategic culture and a defense establishment’s use of intelligence to improve the performance of its own armed forces.

In all areas, the U.S. Navy enjoyed a number of advantages over the Japanese. Since the beginning of the nineteenth century, its main mission was to safeguard America’s oceanic commerce and trade. Thus, the Navy had a legacy of keeping a lookout on foreign rivals, even though long-standing traditions of avoiding involvement in international conflicts prevented it from rising to the ranks of the world’s leading maritime forces during the first hundred years of its existence.³⁹ By the 1900s, the protection of the Pacific areas became a top national security concern, owing to the growing presence of U.S. economic and imperial interests in the region, and the Japanese had been identified as the most likely opponent. War Plan Orange, originally drawn up in 1907, stated that in the event of a conflict against Japan, U.S. forces needed to undertake an extended effort in order to emasculate the IJN’s capacity to fight.⁴⁰ The main aim was to secure control over the vast expanses of the Pacific Ocean, and thereafter blockade Japan’s Home Islands in order to curtail its supplies of vital war materials from abroad. While in peacetime isolationist opinion within the public and government discouraged the commitment of large forces overseas, the Navy’s strategic thinking dictated that wars were to be fought by optimizing the nation’s industrial resources, and constructing a vast armada composed of the most modern vessels.⁴¹ Because the Americans had a clear vision of their strategic aims and the means to achieve them, they were well-placed to recognize the types of challenges that the IJN could pose. As a matter of fact, the Orange plan has been credited with laying out the fleet’s requirements in a manner that was so sound that it could easily deal with a wide variety of contingencies.⁴² Naval intelligence policy also explicitly stated that all preparation for war must be premised on the best available information.⁴³ Most important, the available intelligence on the IJN was applied to enable the Pacific Fleet to prevail in a prolonged conflict, where the efficient and widespread use of advanced armaments played a decisive role in determining the outcome.

The practices followed by the Japanese were in striking contrast to those of the U.S. Navy. In a case similar to most imperial powers, Japan’s overseas expansion was driven primarily by economic concerns, namely, to provide its growing industries with a secure source of raw materials and a captive market for their manufactured goods. However, what distinguished Japan’s policy was the extent to which authorities made a haphazard effort to study the problems that could arise in the event of a conflict with rival nations. Because the Japanese had purposely secluded themselves until the 1850s, their defense establishment was inexperienced in gauging foreign states.⁴⁴ Military calculations were not based on facts, but on the notion that Japan would eventually create a new Asian order where it played the dominant role, and the Western nations were to acquiesce in a fait accompli.⁴⁵ The concept originated from the Meiji era of the late nineteenth century, when the ruling elite, in an effort to forge public unity within their newly established nation, created an ideology proclaiming that the Japanese had a preordained right to become the leading power in the Far East.⁴⁶ Thus, a cornerstone of Japan’s strategic thinking was a belief that its people were a superior race, and this aspect precluded an objective opinion of its adversaries.⁴⁷ Navy planners also held a muddled idea on how to defeat the United States, and presumed that wars could be won by dealing a knockout blow at the onset and waiting for Japan’s enemies to offer peace, in the same way the clashes against China and Russia had been conducted at the turn of the twentieth century. Because victory hinged on the success of the initial operations, intelligence activities tended to be geared toward helping the armed forces wage a short campaign. The practice was bound to bring disaster when engaging enemies who insisted on conducting a total war. Nor did the Japanese navy’s leadership carefully consider how Japan was going to compel America to give in, when the latter’s industrial capacity and weapons production was far superior.⁴⁸ IJN personnel paid minimal attention to how Allied capabilities might evolve in the long run, and neglected the need to learn new ways of fighting. To make matters worse, Japan’s triumphs during the commencement of the Pacific War reinforced the deep-seated faith in its ascendancy. By late 1943, when U.S. forces commenced their counteroffensive, and the Imperial Navy faced vastly superior opponents, it was too late to remedy the mistakes. The best intelligence was unlikely to compensate for the fact that Japan’s leaders had decided to initiate a war for which they were ill-prepared.

The U.S. Navy did face difficulties in preparing for hostilities, among the foremost of which was a shortage of intelligence. In many areas, including the use of carrier-based air power and the development of surface warfare doctrine, naval staffs were unable to scrutinize the IJN’s activities. True, one of the key problems that prevented officials from understanding their potential enemy before the Pacific War was their inclination to assume that American doctrines and weapons were superior.⁴⁹ As a result, evidence that indicated that the IJN possessed certain qualities was often ignored. U.S. naval authorities also tended to assume that the Japanese abided by the same rationale as their Western counterparts, which maintained that a weaker fleet could not afford high losses and thus had to move cautiously. Subsequently, even if the Imperial forces initiated hostilities, the prospect of an attack against key U.S. positions in the Pacific, including the Philippines and Hawaii, was considered unlikely. Yet without reliable information, a clear picture was unlikely to emerge. Tokyo carried out its rearmament program with extreme secrecy. The few pieces of data that could be secured tended to suggest that Japan did not have the resources to construct a fighting machine that could equal its Western counterparts. As a result, the Navy Department abided by its opinion that the Imperial fleet was a second-rate adversary who was not to be feared. Nor could U.S. forces adjust their combat methods and technologies in a way that was effective for confronting the Japanese.⁵⁰

The opening months of the conflict saw the Americans continuing to deal with the obstacles arising from an inadequate knowledge of their opponent. The speed with which the IJN and its air arm achieved a complete dominance over Southeast Asia and the western Pacific regions compelled the U.S. Navy to reassess the Japanese. After all, defeat is by far the better teacher, and critical faculties are often sharpened by experiences of failure.⁵¹ Officials acknowledged that the Pacific Fleet needed to reform its combat methods, and confront the Imperial forces by making good use of limited resources. To achieve this end, it was essential to know which enemy strengths to avoid, and the shortcomings to exploit. Intelligence was therefore treated as an integral instrument, and the Navy Department made a substantial effort to supply the Office of Naval Intelligence (ONI), along with the organizations working alongside the Pacific Fleet, with the manpower and material resources needed to work on a wartime footing. However, the trauma of defeat meant that evaluations concerning the IJN focused almost entirely on their advantages. Indeed, the Japanese defeat at Midway in June 1942, and the failure of their Solomons campaign during the autumn, provided the first concrete signs that the Imperial fleet did not have the skill and technological resources needed to prevail. Even then, intelligence on Japanese capabilities remained scarce, because the Americans had yet to engage in extensive operations. Consequently, frontline personnel were tasked to collect information on how the IJN performed, and to analyze the data gained in combat experience.

The evolution of U.S. intelligence also demonstrates how, even in wartime with the increased availability of information, making an accurate evaluation is by no means an easy task. Organizations are not always able to secure data on the doctrines and principles that shape the opponent’s ways of fighting. The question of whether the enemy is likely to reform its techniques and weaponry is open to conjecture. The uncertainty becomes especially visible when engaging an adversary with an alien cultural mindset, such as the IJN. No study of American perceptions regarding the Japanese during the Pacific War is complete unless it addresses the race issue. The ethnic divide between the belligerents had a profound effect on their views of each other. Yet few historians aside from John Dower have extensively studied the subject.⁵² Dower focused mainly on the opinions held by the rank and file of the U.S. Army, as well as the general public. According to his work,