Preface and Acknowledgments

"There is nothing makes a man suspect much, More than to know a little." – Francis Bacon

In the seemingly never-ending debate over the 7 December 1941 Japanese attack on Pearl Harbor, one of the significant topics of contention pressed by some revisionist and conspiracy writers, historians, and critics of the conventional view of the attack and the Roosevelt administration's role in it has been the phenomenon of the so-called "Winds Message" (hereafter referred to as Winds message). In the years after World War II, several writers and scholars and a few politicians espoused the position that this message was a clear warning that the Japanese were going to attack the U.S. fleet at Pearl Harbor. They have also argued that, beyond the simple fact of the occurrence of the Winds message, the contents and importance of this message had been revealed to senior American civilian and military leaders. They have contended further that the failure by Washington to warn the army and naval commands at Pearl Harbor, even though the former had intercepted the warning, made the ensuing calamitous attack inevitable. After the attack, the claims continue, high-level government officials participated in, or oversaw, a destruction of the evidence that such a warning had been received. The two commanders in Hawaii at the time, Admiral Husband Kimmel and Lieutenant General Walter Short, both claimed in later statements during their testimony before the Joint Congressional Committee reviewing the attack that if they had had knowledge of the Winds message they could have prepared for an attack.^[] To some adherents of this claim, the Winds message had acquired a near mythic status within the larger controversy over Pearl Harbor.^[]

During and after the war, the Japanese surprise attack on Pearl Harbor was subjected to a number of investigations by the United States government. In fact, the attack was the subject of eight separate investigations from late 1941 through mid-1946. Among them, three were conducted by the Navy Department, three by the War Department, and one was chaired by Associate Supreme Court Justice Owen Roberts that began within weeks of the attack. The final and most comprehensive was the postwar hearings by the Joint Congressional Committee under the chairmanship of Senator Alben Barkley (D-KY), which, among other things, incorporated all of the evidence, testimony, exhibits, and findings of the previous seven inquiries.^[]

With the exception of the Roberts Commission, which met in late December 1941 and limited its review of decrypted Japanese diplomatic messages, all of the other investigations considered in detail testimony and evidence regarding the Winds message in the two weeks prior to 7 December. Two of the seven Pearl Harbor inquiries prior to the Joint Congressional Committee Hearings of 1945–1946, The Army Pearl Harbor Board (20 July – 19 October 1944) and the Navy Pearl Harbor Court of Inquiry (24 July – 20 October 1944), heard testimony that a "Winds Execute" (hereafter referred to as the "Execute message") had been sent before 7 December. Both investigations concluded that the Execute message had been intercepted sometime on 4 December and that the substance of it indicated war between the United States and Japan and warned of the attack on Pearl Harbor. Both bodies also concluded that knowledge of the Execute message had reached the intelligence staffs of both the Navy and War Departments.^[]

The Eight Investigations of the Pearl Harbor Attack: The Roberts Commission, 18 December 1941 – 23 January 1942 The Hart Inquiry, 12 February – 15 June 1944 The Army Pearl Harbor Board, 20 July – 19 October 1944 The Navy Court of Inquiry, 24 July – 19 October 1944 The Clarke Investigation, 14–16 September 1944, 13 July – 4 August 1945 The Clausen Investigation, 23 November 1944 – 12 September 1945 The Hewitt Inquiry, 14 May – 11 July 1945 The Joint Congressional Committee, 15 November 1945 – 31 May 1946

On the surface, these findings appeared to have some merit because there was a smattering of supportive evidence. The Winds message, that is the warning or alert that was known to some in prewar U.S. intelligence as the "Execute" message, had been intended by the Japanese Foreign Ministry (Gaimusho) as an emergency method to warn its diplomatic posts of a downturn in relations between Japan and the United States, Great Britain, or the Soviet Union. Tokyo expected that, in the time of crisis prior to any hostilities, its diplomats would have to destroy classified papers, as well as their manual codes and ciphers and any cipher machines in their facilities. Tokyo also expected that in such a time of crisis a host country would limit direct communications between Japanese diplomats and the Foreign Ministry, or even totally cut off such links.

To get around this potential severance of communications, the Japanese Foreign Ministry, near the middle of November 1941, had sent special instructions to its diplomats in the United States and Latin America directing them how they were to be kept informed of the status of relations between Japan and the United States, Great Britain, and the Soviet Union. One method involved the placement of innocuous phrases about the weather in shortwave voice news programs transmitted overseas by Japanese government radio stations. This method of sending secret messages is referred to as an "open code." These phrases indicated with which country relations with Japan were in trouble:

East Wind Rain – United States

North Wind Cloudy – Union of Soviet Socialist Republics

West Wind Clear – Great Britain

Based upon the evidence and testimony gathered by the various Pearl Harbor inquests, as well as later additional claims made by certain U.S. navy personnel, some scholars and writers from the postwar years advanced revisionist or conspiracist theories about the attack on Pearl Harbor and further claimed that such an Execute message had been sent and intercepted as many as three or four days before the Japanese strike. They also contended that the U.S. government had conspired to suppress this knowledge about the possession of the warning message. According to their version of events, high government officials had ordered the destruction of critical records, doctored other official papers, and badgered potential witnesses into silence or forced them to make scripted and mendacious testimony.

The primary, and almost exclusive, source fueling these claims of a conspiracy surrounding the Winds message was Captain Laurance Frye Safford, the founder and first commander of the U.S. Navy's code-breaking unit, OP-20-G. Safford had started the Navy's cryptologic section in the 1920s and commanded it until 1942. Safford first publicized his version of events concerning the Winds message in early 1944 when he testified before the Hart Inquiry. He later repeated variations of his initial story before the Army Board and the Navy Board of Inquiry later that same year. It was largely because of Captain Safford's high reputation within the cryptologic and intelligence communities that his charges were taken seriously by the various hearings before which he testified at the time.^[]

Today, a substantial portion of the public still subscribes to this conspiracy view of the Winds message. This group could very well have grown over the years thanks to the proliferation of websites on the Internet about Pearl Harbor that contain entries about the Winds message. Many of these sites circulate the same charges and evidence that were first raised in the written literature of the last decades.^[]

Of course, there are many scholars and researchers who are skeptical or critical of the various revisionist and conspiracist claims revolving around the Winds message. Most of these researchers and scholars point to the serious technical and contextual shortcomings in the evidence put forward by those who see conspiracy behind the handling of the Winds message. Others suggest that the conspiracy claims are based on a selective reading of the testimony and evidence that surfaced during the Pearl Harbor hearings and in later years.^[]

Scholars and writers who have written about the Winds message from both sides of the controversy have been confronted with a mass of evidence, mostly in the form of detailed and difficult testimony during the seven hearings that addressed this issue. On top of this considerable body of evidence, there are several thousands of pages of documents to peruse as well. Generally, scholars have restricted their examination of the sources to a limited number of basic documents, usually a small number of translations of related Japanese diplomatic messages, selected excerpts from testimony given at the several Pearl Harbor hearings, and short, apt quotes from individual pieces of correspondence of the principal personalities. Yet, even the more detailed narratives of events still leave questions unanswered about how the story that the execute message might have been intercepted, the context of the original instructions, or "setup message," and the timing and origins of Captain Safford's version of events.

The reason for the shortcoming is that the available evidence consists of more than the documents gathered by the various hearings and published as exhibits. The U.S. government's departments, agencies, and commissions collected far more material than was ever used as exhibits. Then, again, there is some additional relevant material that has existed outside of the many hearings, and this latter material has seldom been invoked in the literature of the Winds message controversy. The existence of all of these sources suggested that it may be possible to examine important aspects of the Winds message story in a deeper fashion than before.

To the authors of this history, it seemed that at least two critical areas of interest in the Winds message controversy needed better explanations. The first concerns both the substance and circumstances of the Japanese warning system supposedly centered on the Winds message. As we shall see later, the Japanese Foreign Ministry was very specific when it set up the text, format, and procedures in its instruction message to its diplomats. At the same time, the Japanese also issued further, and in some cases, parallel instructions for similar systems that mandated code destruction, as well as other ways to inform its diplomats of the state of relations with the United States. The existence of these other systems will be told as well.

An important element related to the Japanese warning system is how the United States radio intelligence apparatus reacted to the knowledge of the instructions from Tokyo intercepted in late November 1941. Obviously, at the heart of the controversy is whether or not the Winds Execute message was ever heard. The answer to this issue is contingent on understanding the actions of the various elements of the U.S. government involved in the story: the U. S. Army's Signal Intelligence Service, the U.S. Navy's OP-20-G, and the Federal Communications Commission.

The second area of interest concerns the evidence for the various claims put forward by Captain Safford. In early 1946, Safford offered the Joint Congressional Committee a written and detailed memorandum of his allegations. Usually, it is this document to which reference is made regarding his allegations that the Execute message was intercepted and that knowledge of this event was suppressed. But Safford had been making similar charges for the better part of two years. And what he stated initially before the Hart Inquiry regarding the Winds message differed from what he asserted in early 1946. At the same time, there is important documentary information from before the hearings that point to the origins of his thinking and his search for what he believed was the evidence of the missing Winds execute message.

It is clear that only a deeper review of the documentary sources could resolve the many questions surrounding the Winds controversy.

This history, then, intends to present the story of the Winds message with an emphasis on selected documentary evidence, that is, with attached images of relevant and important documents. While a handful of the documents presented here have been seen either as images or in transcribed form, such as can be found in the several volumes of exhibits of the Pearl Harbor hearings, this single volume contains all of the standard, critical documents. This history also includes many documents that have not been seen before, such as the U.S. Navy's translation and cryptanalytic worksheets of the 19 November 1941 Japanese Winds instruction messages, and the translation worksheets of the Federal Communications Commission from early December 1941.

After reviewing the documents and discussing their context within the chronology of the Winds message controversy, this history should answer the following questions: (1) What was the cryptology behind the Winds message? That is, what were the communications and cryptography used by the Japanese to set up the Winds warning system and then what, if any, warnings were actually sent? At the same time, how did the American radio intelligence and code-breaking agencies intercept, decrypt, and interpret the Japanese messages, and how did the Americans react to the information about the Winds warning system? (2) What were the origins of the controversy that encompassed the Winds message? What claims were put forward regarding the intercept of the Winds execute message, as well as claims for a purported cover-up?

Two further questions are suggested by an examination of the documents. The first is this: Was there any way in which the warnings contained in the Winds message, which were aimed at Japanese diplomats, could have been construed as a specific warning of an attack on Pearl Harbor? As we shall see, a few of the major characters in the controversy believed this connection existed and some scholars in later years have repeated the claim. The second question is, what effect did the Winds message have upon the effectiveness of the operations of prewar American cryptology? There is no doubt that the Americans reacted to the knowledge of the possibility of a Winds execute warning message being sent. So how did the knowledge of the potential warning message affect American cryptology? Did the American reconfigure their operations, and, if so, how and to what effect on their overall workings?

Why a Documentary Approach?

One of the by-products of the eight hearings on the attack on Pearl Harbor was the retention of the documents that ordinarily would have been destroyed as part of the legally prescribed records disposition process employed by the military services and other agencies of the federal government at the time. Also, many personal records, especially those of individuals important to the events of late 1941, were retained as evidence gathered by the hearings, or for use in later memoirs or histories. This tide of source material has allowed scholars the opportunity to examine all aspects of the attack in a detail seldom replicated.

Even the most highly classified intelligence of the timen – the decrypts and translations of Japanese diplomatic messages, including those encrypted in the cipher machine known to the Americans as Purple, were available to the various hearings. The intelligence from all such decrypts and translations was categorized under the title of "Magic." During the various investigations, many of these translations were entered into the record as exhibits and were sometimes discussed in great detail at the hearings. Along with the diplomatic translations, army and navy personnel associated with cryptology often discussed at length other aspects of radio intelligence, including such arcane disciplines as direction finding and traffic analysis. This exposure allowed later scholars and writers to discuss in detail these elements of codebreaking and radio intelligence in their works.

Yet, the abundance of source material did not always lead to a clear understanding of what constituted the Winds message or the context around it. The Winds message phenomenon often fell victim to the claims and counterclaims about the content, format, timing, and meaning of the warnings contained within the actual text. To the authors of this history, many of the arguments, both pro and con, regarding the questions of whether a Winds Execute message was intercepted prior to 7 December and whether there was a cover-up or a conspiracy to suppress evidence of the intercept, appeared to be disconnected from the available documentary evidence. Often, the explanations and descriptions about the execute message seemed to be talking about something not at all like what Japanese diplomats had been instructed to listen for on their shortwave radios. At the same time, these discussions often paid little attention to the context of all of the diplomatic messages during the crisis period before 7 December; it was, at times, as if the Winds message existed in a separate reality.

It appeared that if we were to enter the fray over the Winds message, it was necessary to bring along as much of the documentary evidence as we could retrieve. So this history, really a documentary history of the controversy, is intended to make available to all sides the basic sources: the worksheets and the translations of the pertinent Japanese diplomatic correspondence, the logs and chronologies of events, the pertinent correspondence amongst the major players, and associated memo-random and notes. With these papers available readily to everyone with an interest in the Winds story, it is hoped that we can achieve a resolution to the controversy.

The Sources and Nature of the Documents

The publicly available archival sources of the documents used in this collection were legion. Foremost among the collections is the evidence contained in the Joint Congressional Committee Hearings on Pearl Harbor (1945–1946). The congressional hearings incorporated the evidence and testimony from the previous seven hearings and boards into its report. The Committee's Hearings included thirty-nine volumes of testimony and documentary evidence along with its Final Report.

Interestingly, the enormous number of pages of material – estimated by some at about 15,000 pages of testimony and 9,000 pages of documentary exhibits – do not reside in only one archival location. As several U.S. cabinet departments, agencies, boards, and commissions contributed material to the various investigations, the resulting documentation can be found among several Record Groups in the National Archives, at both the Archives in Washington, D.C., and at Archives II in College Park, Maryland.

There are a number Records Groups (RG) that hold documents of interest and relevance: RG 59, Records of the U.S. Department of State; RG 80, Records of the Secretary of the Navy, Records of the Pearl Harbor Liaison Office Files; RG 128.3, Records of the Joint Committees, 51st – 98th Congresses; RG 165, Records of the War Department; RG 38, The Records of the Chief of Naval Operations (CNO), Chief Naval Security Group; RG 457, the Records of the National Security Agency/Central Security Service (NSA/CSS); and RG 173, the Records of the Federal Communications Commission (FCC).

During the research we also consulted smaller collections of records such as the Laurance F. Safford Collection maintained by the National Cryptologic Museum Foundation, Fort George G. Meade, Maryland, and the David Kahn Collection also accessible from the National Cryptologic Museum Library. A further useful set of material regarding the Winds controversy is found in the collection of papers of Admiral Husband E. Kimmel, located in the archives of the American Heritage Center at the University of Wyoming, Laramie, Wyoming.

There is another minor source for this work that merits a special mention: the working papers of the late former NSA Historian Henry F. Schorreck. During his twenty-one-year tenure as the NSA Historian, Henry, or "Hank" as everyone called him, assiduously gathered or saved important caches of cryptologic records, especially those from the many decades preceding the establishment of the National Security Agency. Among his papers were copies of the encoded versions of the original Japanese instructions to the Winds message, the cryptanalytic and translation worksheets, and final translations. All of these documents are copies of the originals, which can be found in Record Groups 38,80, and 457. It was the discovery of these worksheets that inspired the authors to proceed with this book.

The primary criterion for including a document in this history as an exhibit was its relevance, interest, or importance to either the cryptology of the Winds message or the ensuing controversy over whether an execute message had been sent and intercepted. While an estimated few hundred documents and scores of pages of testimony were generated by the seven hearings and inquiries that considered the question of the Winds message, a much smaller portion of the material actually passed muster when it came to relevance, insight, and importance. Those we did not include fell to the side for reasons of redundancy, prior publication, or because they simply did not add anything of value to the story. Interestingly, about forty percent of the exhibits that are contained in this history originally were not featured as exhibits from any of the eight Pearl Harbor hearings. These rather unique documents were discovered during research into the Pearl Harbor holdings of the many record groups and collections the authors reviewed for this history.

This volume finally came to contain fifty-six exhibits of the most interesting and relevant documents on the Winds message controversy. They have come from many sources and represent many of the episodes of the narrative of the Winds message. It is possible that some readers may dispute our choices or press for other items. But we believe that we have selected the documents that best tell the story.

Sometimes a version of a document was just too unique to pass up, and, therefore, we felt it should be included as an exhibit. During our research, we encountered copies of the translations of Winds instruction messages with substantial handwritten marginalia by William F. Friedman, the putative doyen of early American military cryptology. Friedman was a minor character in the ensuing controversy, having discussed aspects of the cryptologic context of the Winds message with Captain Safford. Friedman's notes on the translations are useful comments on Safford's claims, and to the authors appeared more useful (and insightful) than unannotated versions, both of which are available at the National Archives.^[]

For those who have researched any portion of the enormous cache of records related to Pearl Harbor, it soon becomes obvious that, while the hearings by Joint Congressional Committee and the other boards and courts conducted a complete as possible and exhaustive task of identifying pertinent records, the documents available in the various record groups are not originals, but versions or copies – whether they be photocopies, transcriptions, or paraphrases. This is not unexpected or unusual. The original records belonged to the various U.S. government departments and commissions, so making copies for the purpose of the hearings and investigations was the proper procedure.

Sometimes making a copy made good sense from the standpoint of preservation or usefulness. Some records consisted of handwritten notes, logs, or letters on paper that would have never stood up to the handling required during an investigation. At the same time, some of these same records were handwritten and for them to be easily referred to required that the text be transcribed. Therefore, many of the records of the various hearings available in the national Archives are, in reality, transcribed versions of the originals.

In some cases, records were entered as hearing exhibits marked as "paraphrases" of the original. This usually occurred when documents that were to be cited as exhibits could not be declassified in their entirety In these cases, the paraphrase was made when certain technical aspects of a message, such as communications or cryptographic details about the correspondence, or when information regarding sources or intelligence methods required protection. Examples of paraphrasing can be found in some of the October 1945 messages from General Douglas MacArthur's Headquarters in Tokyo to the War Department regarding interviews with Japanese nationals relating to Pearl Harbor.^[]

The Terminology Used in This History

Beginning with the initial revelations of the World War II Ultra success by the Allies in the early to mid-1970s, notably F.W. Winterbotham's The Ultra Secret, the public has been exposed to numerous arcane terms associated with the business of intercepting messages and the making or breaking of codes and ciphers. Unfortunately, from the early literature on the Ultra story through today, there still exists among many scholarly and popular writers the tendency to confuse or incorrectly mix these terms. This misuse of terms often has led to inaccuracies such as describing the German Enigma device as a "code machine," or confusing the term Purple – the covername given to the analog device used to decrypt Japanese high-level machine cipher messages – with the solution of the Imperial Japanese navy's main operational code, known as JN-25. Such mistakes in the terminology invariably lead to error-prone narratives and some incorrect conclusions about the role and importance of codebreaking to the outcome of World War II. For the reader's ease, many of the relevant terms used in this history will be explained below.

COMINT is the acronym for communications intelligence and can be defined as measures taken to intercept, analyze, and report intelligence derived from all forms of communications. This definition describes broadly and most accurately the entire American communications intelligence structure and process in late 1941 that existed to exploit Japan's and other nations' communications. This structure included the principal American code-breaking centers in Washington, D.C. It also includes the monitoring stations manned by American soldiers, sailors, marines, and civilians who listened in on the world's communications. It further encompasses the work of the analysts who decrypted, translated, and reported the contents of the intercepted messages, as well as those who passed this intelligence to the national command authorities in the White House, the Departments of State, War, and the Navy, and the service chiefs of staff for the armed services. It also refers to the theater sites, known as Communications Intelligence Units, and staffs who reported directly to the Commanders of the Pacific and Asiatic Fleets. The structure also connects, as well, to collaborating Allied agencies such as British Government Code and Cypher School (GC&CS) and its subordinate stations, especially the component in Singapore that was part of the Far East Combined Bureau (FECB). A closely related term is radio intelligence, which was more commonly used during the period before Pearl Harbor. Radio intelligence usually referred to intelligence gathered from radio transmissions short of actual decoding or decryption of messages, but often was synonymous with communications intelligence.

A similar term, signals intelligence, or SIGINT also is often used synonymously with COMINT. Signals intelligence, though, includes a broader range of emissions as targets. SIGINT includes the intercept, processing, and reporting of intelligence derived from noncommunications signals such as radar and navigational beacons. In late 1941, the idea of deriving usable intelligence from such signals was relatively new. At that time, the main use the of such intelligence, now referred to as electronic intelligence (ELINT), was to develop so-called countermeasures to such signals, exemplified best by the use of the famous British "window" or chaff – strips of aluminum that reflected German radar signals and obscured their tracking of Allied bombing missions over Europe.

Another general term, cryptology, is defined as the study of the making and breaking of codes and ciphers. Cryptography is the study of the making of codes and ciphers. Cryptography is often used to describe both the entire inventory of such items for a country or some discrete element within it, such as "Japanese diplomatic or naval cryptography." A code is defined as a method in which arbitrary, and often fixed, groups of letters, numbers, phrases, or other symbols replace plaintext letters, words, numbers, or phrases for the purposes of concealment or brevity. To encode is to transform plaintext into a coded form. To decode is the break the code back to its underlying plaintext. A variation of a code is known as an "open code" or codeword. This occurs when a seemingly innocuous or ordinary word, words, phrase or number is used in a message or transmission to convey certain information or initiate an action previously agreed upon by the sending and receiving entities. The true meaning of an open code or codeword, as opposed to its literal or accepted meaning or connotation is supposed to be denied to anyone else who might be listening other than the intended recipient. As will be seen, this type of code plays a significant part in the Winds story.

Before World War II, codes came in the forms of pages, tables, or a book. On each page of a codebook or table, a plaintext word or phrase is aligned opposite its code unit or code group equivalent. Codebooks were arranged alphabetically or numerically in order of the plaintext, making it easier to encode a message. To facilitate decoding by the intended recipient, a second codebook was used that was arranged alphabetically or numerically by the code group. This procedure of using two separate books, known as a two-part code, was intended to complicate the cryptanalytic recovery of the codebook, a process known as "bookbreaking."

A cipher is a method of concealing plaintext by transposing its letters or numbers or by substituting other letters or numbers according to a key. A key is a set of instructions, usually in the form of letters or numbers, which controls the sequence of the encryption of the text or the decryption of the cipher back to the original plaintext. A cipher that results from transposing text is known as a transposition cipher. A cipher resulting from substitution is known as a substitution cipher. Transforming plaintext into cipher is called encryption. Breaking cipher back to plaintext is called decryption.

Two examples of famous ciphers from World War II are the Axis cipher machines, the German Enigma and the Japanese device, codenamed Purple by the Americans, but known to the Japanese as the 97-shiki O-bun In-ji-ki, or Alphabet Typewriter '97. Both machines substituted letters for plaintext elements according to daily key settings for each device. Ironically, though, most ciphers used by all sides during World War II overwhelmingly were manual in nature. That is, they used paper charts, tables, and key.

Many countries used various ciphers to further secure codes they employed. This entailed applying any one of a number of encryption techniques to the code groups, thereby additionally concealing the "true" code groups. One encryption method was to add random groups of number, or digital, key to codes that employed numeric code groups. The resulting new, or cipher, group was then transmitted. This was the technique used by the Japanese navy to encrypt JN-25 operational code group. Japanese diplomats used a transposition cipher, namely, scrambling or breaking up the sequence of the true code groups, usually composed of letters. This method of additional encryption, sometimes called super-encryption or super-encipherment, made decoding even more difficult: before a codebreaker could recover the plaintext value associated with a code group, he or she had to first recover the true code group.

Cryptanalysis is the analytic method whereby code or cipher text is broken back to its underlying plaintext. Traffic analysis is the analytic method or methods whereby intelligence is derived from the study of the communications activity and the elements of messages short of actual cryptanalysis. The difference between cryptanalysis and traffic analysis can be explained through an analogy of a piece of mail. Traffic analysis can be compared to the study all of the external information on a letter's envelope and even an analysis of the characteristics of the envelope, such as its weight. Cryptanalysis is the reading of the contents of the letter.

Nations like Japan used a number of cryptographic systems within a single service or department like the navy or the foreign ministry. These services often used ciphers and codes of increasing complexity depending upon the nature and sensitivity of the information that was to be protected. Any station, whether an army unit, ship, or diplomatic facility, often had in its possession the cryptographic materials necessary to send and receive messages that involved a number of separate codes or ciphers. In order to distinguish between cryptographic systems used for various messages, and to further conceal what system was being used, cryptographers resorted to the use of a discriminant or indicator. This item was a group or some other combination of letters and numbers that identified to the recipient of the message what cryptographic system was used to encode or encrypt that particular text. Some indicators appeared in the message text, others in the message's header. Sometimes an indicator also identified a particular recipient or larger audience of the message. Just as likely, foreign cryptanalysts who had gained a working familiarity with a particular code or cipher easily could recognize such indicators, which, in turn, could facilitate the effort to solve the system.

To make reading easier, as well as to avoid clumsy repetition of terms, we will use terms like "cryptology," "communications intelligence," "COMINT," "signals intelligence," "SIGINT," and "radio intelligence" interchangeably either as adjectives or as nouns by which to describe the overall American intelligence system to exploit Japanese communications and cryptography. Using these terms as general descriptors will not sacrifice accuracy and will make the text more readable. Any other special or one-use terms from cryptology will be identified when they are encountered in the text.

Organization of the History and Exhibits

In this history we will refer to a particular documentary exhibit at the point in the text as necessary. The reference will be contained within brackets "[ ]" with the appropriate exhibit number. The exhibits are listed in the Table of Contents and are attachments at the end of this volume.

In the first chapter we will provide a short background sketch of the political and strategic situation in the Pacific and East Asia, especially paying attention to the diplomatic confrontation between the United States and Japan over the issue of Tokyo's invasion of China. In this same chapter, there will also be a discussion of the early cryptologic operations of the United States against the communications and cryptography of Japan's military, navy, and foreign ministry.

The second chapter will recount the cryptologic background to the Winds instruction messages, which includes the intercept, analysis, processing, and reaction to them. The background to the specific cryptographic system used by Japan to secure the instructions, as well as the American solution to this system also will be discussed in some length. The next chapter will consider the reaction by United States military and naval intelligence to the instructions in the Winds messages. Specifically, we will consider the measures taken for further monitoring and the subsequent intercepts that were made, including purported and actual Winds message. Following this, in chapter four, we will discuss the controversy surrounding the Winds message and examine the chronology and substance of the claim put forward by Captain Laurance Safford before the various Pearl Harbor hearings that a Winds execute message indeed had been sent and intercepted by the United States government prior to the Japanese attack of 7 December 1941.

This book concludes with a chapter that considers the Winds message story as a way of measuring the effectiveness of the prewar U.S. cryptologic system in handling the apparent warning that it appeared to be at the time. We will also briefly consider how the controversy played out within the context of the story of Pearl Harbor.

A few comments on citations used in this book are necessary. Throughout this work, when a reference is made to material from the thirty-nine-volume set of the Joint Congressional Hearings and the single volume Final report, the citation will be for the specific volume, or "Part," and the page number of the volume. For example, "PHH, Part 8: 555," refers to page 555 of Volume Eight of the Hearings. This definition is important because the forty volumes of the various inquiries, boards, and committees carry a dual system of page notations for the transcripts and exhibits. Whenever speakers in the various hearings refer to a page of previous testimony, it is to the particular hearing or inquiry transcript page number of its testimony. The transcript page number can be found imbedded in the transcript of testimony within a set of brackets, "[ ]." This method of reference can be confusing to first-time researchers using the Pearl Harbor Hearings volumes. The natural inclination is to go to the volume page number, but it can mean the transcript page number. For our purpose, though, we will refer to the volume page number.

Acknowledgments

As in many other endeavors, this work could not have been done without the help of many others. The authors gratefully acknowledge the following people and their contributions.

Sadly, though, this section must begin with a statement about one of the authors, David Mowry, who passed away in July 2005. When David and I began this manuscript in 2004, we originally envisioned a short tutorial on cryptanalytic and translation techniques of the pre-World War II era aimed specifically at professional cryptologists. As we progressed through the material, especially those papers concerning the postwar hearings, we both agreed that there was a need for a history of the Winds controversy. But this work should not be just a narrative. Rather, it had to be a documentary history that would bring the source material to the public. Throughout the initial draft of this book, especially with regards to the cryptanalytic part of the story, Dave provided the technical expertise necessary to understand the work of the army and navy codebreakers. He also proved to be a demanding reader of the initial drafts. Dave was a voracious reader, and he possessed a great joy for life and took much pleasure in the intellectual challenge inherent in cryptology. All that was this man will be sorely missed by his colleagues and friends.

"West Winds" represents the initial effort by the Center for Cryptologic History to produce a documentary history. Many people worked on a book whose format and organization were decidedly different than previous productions by the Center. Principal among them were my editor, Stephanie Shea, who accepted each of my changes, additions, and updates to the text and exhibits with a forbearance that was as admirable as it was enduring. Barry Carleen, the chief of the publishing team, took on the challenge to see this project through. We also want to acknowledge the contributions of the members of the CCH, Dave Hatch, John Clabby, and Sharon Maneki, who reviewed the manuscript and offered suggestions and corrections. We also wish to acknowledge the advice from a number of scholars from outside of the NSA. This group included David Kahn, Norm Polmar, Raymond Schmidt, Colin "Brad" Burke, and Betty Koed. At the U.S. National Archives, we would like to thank both Matthew Olsen and Kris Wilhelm for their help in locating documents in the records of the State Department and congressional committees. Overseas, in the United Kingdom, gracious help in locating material about the British communications intelligence effort in the Far East came from Michael (Mick) Smith and the late Peter Freeman. Finally, I wish to acknowledge the technical help from those people whose current duties prohibit them from being thanked publicly.

Notes

^[]

^[] Roberta Wohlstetter, Pearl Harbor: Warning and Decision (Stanford, CA: Stanford University Press, 1962), 388; "Hearings Before the Joint Committee on the Investigation of the Pearl Harbor Attack, Congress of the United States, Seventy-Ninth Congress, Pursuant to Senate Concurrent Resolution No. 27 Authorizing an Investigation of the Attack on Pearl Harbor on December 7, 1941, and Events and Circumstances Relating Thereto." (Washington, D.C.: United States Government Printing Office, 1946). For Kimmel's statement, see Part 6: Pages 2551–2, and for Short's statement see Part 7: Pages 2957, 2960.

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^[] For the thesis that connects the Winds message with the attack on Pearl Harbor, see, among others, Rear Admiral Robert Theobald, USN, The Final Secret of Pearl Harbor: The Washington Contribution to the Japanese Attacks (New York: The Devin-Adair Company, 1954), 134–152; John Costello, The Pacific War, 1941–1945 (New York: Quill Books, 1981), 643–649; and John Toland, Infamy: Pearl Harbor and its Aftermath (New York: Berkeley, 1983), 141–144 and 209–217, and George Victor's The Pearl Harbor Myth: Rethinking the Unthinkable (Dulles, VA: Potomac Books, 2007), 69–75. Beginning in the latter years of World War II, and especially after the revelations of the Joint Congressional Committee Hearings (1945–46), there has been a bounty of so-called revisionist histories of the attack on Pearl Harbor. In truth, most of these works were largely politically inspired by the anti-Roosevelt sentiments held by a number of scholars such as Charles Tansill, Back Door to War: The Roosevelt Foreign Policy, 1933–1941 (Chicago: Henry Regnery Company, 1952) and Charles Beard, President Roosevelt and the Coming of the War, 1941 (New Haven, CT: Yale University Press, 1948), who saw an FDR plan at work to provoke the Japanese attack. Of the more recent revisionist works, some come from writers whose approach can be characterized as "conspiracist" or "conspiratorialist." This group of writers claims that intelligence about Japan's intentions to attack was available to various individuals at many levels in the United States government and yet this information was withheld from Admiral Kimmel and General Short prior to the attack. Their story continues with the further claim that after the war knowledge of this intelligence was suppressed or destroyed and individuals were warned to keep silent. Robert Stinnett's Day of Deceit: The Truth about FDR and Pearl Harbor (New York: The Free Press, 2000) and George Victor's The Pearl Harbor Myth are the most recent example of the conspiracy literature about Pearl Harbor. Interestingly, Mr. Stinnett downplays the significance of the Winds message.

There has not been a recent review of the Pearl Harbor literature for some time. A monograph, What Every Cryptologist Should Know about Pearl Harbor, is a good, but dated, review (1987) and is available to the public at the National Cryptologic Museum. For a some what more dated summary of the various controversies, including the Winds message, see Hans Trefousse's Pearl Harbor: The Continuing Controversy (Malabar, FL: Robert E. Krieger Publishing Co., 1982).

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^[] "Hearings Before the Joint Committee on the Investigation of the Pearl Harbor Attack, Congress of the United States, Seventy-Ninth Congress, Pursuant to Senate Concurrent Resolution No. 27 Authorizing an Investigation of the Attack on Pearl Harbor on December 7, 1941, and Events and Circumstances Relating Thereto." (Washington: United States Government Printing Office, 1946), Thirty-Nine volumes. Hereafter referred to as "PHH." A final committee report was issued with the title "Report of the Joint Committee. . . etc." This volume is hereafter referred to as "PHR." For a limited but useful index to the hearings, see Stanley H. Smith, Investigations of the Attack on Pearl Harbor (New York: Greenwood Press, 1990).

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^[] For a summary by the Congressional Committee on the findings about the Winds message by the Naval Court of Inquiry and the Army Pearl Harbor Board, see PHH, Part 16:2314–16. Also see PHH, Part 39: 224–226, for the Army Pearl Harbor Board finding on the Winds message and 324–325 for the finding of the Naval Court of Inquiry.

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^[] Safford's statement to Congress and subsequent testimonies can be found in the various hearings: Hart Inquiry, Part 26:388–395; Army Pearl Harbor Board, Part 29: 2366–2378; Hewitt Inquiry, Part 36: 66–77, and the Joint Congressional Committee Hearings, Part 8:3577–3893. For an evaluation of Safford's role, see Gordon Prange's synopsis in Pearl Harbor: the Verdict of History (New York: McGraw-Hill, 1986), 317–330; Also see PHH, Part 16:2316–19, for the congressional committee's summary of Safford's role in the Winds controversy.

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^[] For example, a search for "winds message," with Pearl Harbor, returns hundreds of websites, many of which subscribe to the claim that the Execute message was sent prior to the attack and that the message was a clear warning of the attack on Pearl Harbor. Examples of such sites – www.geocities.com/PENTAGON/6315/pearl.html, or www.carpenoctem.tc/cons/pearl/html, and www.thenewamerican.com/tna/2001/06-04-2001/vol17no12_fact.html

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^[] A short list of these writers includes Gordon Prange, Pearl Harbor: the Verdict of History, 312–330; Roberta Wohlstetter, Pearl Harbor: Warning and Decision (Stanford, CA: Stanford University Press, 1962), 50–53; Ronald Lewin, The American Magic (New York: Farrar, Strauss, and Giroux, 1982), 70–76; and David Kahn, The Codebreakers: The Story of Secret Writing (New York: MacMillan Company, 1967), 32–47.

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^[] For an unmarked version of this translation, see SIS Translations 25432 and 25392, both from Tokyo to Washington, 19 November 1941, located in National Archives, College Park (NARACP) RG 457, Entry 9032, Box 301, Multinational Diplomatic Translations (MNDT).

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^[] PHH, Part 13:394