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Pearl Harbor: Warning and Decision
It would be reassuring to believe that Pearl Harbor was just a colossal and extraordinary blunder. What is disquieting is that it was a supremely ordinary blunder. In fact, 'blunder' is too specific; our stupendous unreadiness at Pearl Harbor was neither a Sunday-morning, nor a Hawaiian, phenomenon. It was just a dramatic failure of a remarkably well-informed government to call the next enemy move in a cold-war crisis.
446 pages, Paperback
First published June 1, 1962
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September 8, 2020
Pearl Harbor is a dramatic and well-documented example of an attack portended by a variety of signals, which nonethless achieved complete and overwhelming surprise. The detection, communication, and interpretation of picked-up signals strongly affected American actions from the Navy and Army headquarters in Honolulu to the War Department and the White House in Washington. As it turned out, the knowledge available to those in position to prevent the attack were too decentralized for any administrative body to make a consistent decision. Roberta Wohlstetter explains that, indeed, many American politicians and military leaders were aware of the possible consequences of the oil embargo against Japan and anticipated an attack on Oahu or a surprise raid on some other spot in the Pacific. Yet, they did not suppose that this spot might happen to be Pearl Harbor. Additionally, their attention was already fully focused on the European stage, where the major dramas of the war were unfolding, and to turn that attention away for long enough to consider an outright onset on Hawaii was impossible.
Another major factor that contributed to the total surpise of the Japanese raid were the many imperfections of the U.S intelligence services, which needed restructuring. Tracing the signal from the moment it was picked up to the moment it arrived at the decision-making center, Roberta Wohlstetter notices that all signals announcing Pearl Harbor were always accompanied by competing or contradictory ones, useless or even harmful for anticipating the disaster. In addition, the signal picture of the limited locale of Honolulu proved to be amazingly complex, and the mass of signals grew increasingly dense and freighted with ambiguities the closer it moved to the headquarters in Honolulu and Washington. This additional chaos of conflicting intelligence further confused and misled the already flawed U.S investigation services, making it almost impossible – or at least very hard – for them to anticipate the impending disaster.
On the other hand, as Wohlstetter asseses, the Japanese investigation was quite efficient, and its estimates of American forces were correct. Japan considered the dormancy of America a great opportunity for coordinated surprise raids throughout the Pacific, which – the Japanese decision-makers hoped – would later prevent a major retaliation by U.S forces.
In the book, Roberta Wohlstetter opens her account with the local scene in Honolulu and the last few hours before the raid. Her study provides a very insightful analysis of the American response to the "warnings" and of all the factors due to which the attack on Pearl Habor remained a staggering surprise. Very interesting and detailed history.
Another major factor that contributed to the total surpise of the Japanese raid were the many imperfections of the U.S intelligence services, which needed restructuring. Tracing the signal from the moment it was picked up to the moment it arrived at the decision-making center, Roberta Wohlstetter notices that all signals announcing Pearl Harbor were always accompanied by competing or contradictory ones, useless or even harmful for anticipating the disaster. In addition, the signal picture of the limited locale of Honolulu proved to be amazingly complex, and the mass of signals grew increasingly dense and freighted with ambiguities the closer it moved to the headquarters in Honolulu and Washington. This additional chaos of conflicting intelligence further confused and misled the already flawed U.S investigation services, making it almost impossible – or at least very hard – for them to anticipate the impending disaster.
On the other hand, as Wohlstetter asseses, the Japanese investigation was quite efficient, and its estimates of American forces were correct. Japan considered the dormancy of America a great opportunity for coordinated surprise raids throughout the Pacific, which – the Japanese decision-makers hoped – would later prevent a major retaliation by U.S forces.
In the book, Roberta Wohlstetter opens her account with the local scene in Honolulu and the last few hours before the raid. Her study provides a very insightful analysis of the American response to the "warnings" and of all the factors due to which the attack on Pearl Habor remained a staggering surprise. Very interesting and detailed history.
March 13, 2013
This is a policy wonk's book: it takes a surprise attack and attempts to decipher whether or not there were adequate warnings about it. Roberta Wohlstetter wrote it in 1962 in part because her husband, a nuclear strategist with the U.S. government, was worried about different scenarios involving nuclear attack during the Cold War.
A modern reader is likely to read the introduction and ask the same questions that the author does -- but concerning the 9/11 terror attacks on the World Trade Center. In fact, this book has had a resurgence in readership because Donald Rumsfeld recommended it highly to colleagues while serving as Secretary of Defense in the post-9/11 era.
And one of Rumsfeld's press conferences had him summarizing the issues for those reading intelligence signals :
"There are known knowns; there are things we know we know.
We also know there are known unknowns; that is to say, we know there are some things we do not know.
But there are also unknown unknowns – the ones we don’t know we don’t know."
Though Rumsfeld was mocked for the lack of clarity in that quotation, it is precisely this definition sought by he author in evaluating the information available just before the Pearl Harbor attack.
Wohlstetter looks at all of the evidence and much of the noise surrounding decision-making of key military and civilian leaders in the months leading up to December 7, 1941 and the attack on Pearl Harbor. She asks what information was present; what background noise might have obscured a message; and what assumptions were in place for key leaders.
The book is primarily based on the 39 volumes of the Congressional Hearings published in 1946, which is both a strength and a weakness. The hearings were detailed but held five years after the attack on Pearl Harbor when even the best memories had changed and key documents lost or destroyed. In addition, Wohlstetter ignores or misses some key elements, such as warnings at the end of January, 1941 from Joseph Grew, the American ambassador to Japan, that the Japanese were planning an attack on Pearl Harbor.
But it is a valuable piece of research, bringing together a large number of pieces of evidence and all of the key players. There are surprises for even those readers very familiar with the story of the American entry into World War II, including Gen. George Marshall's description of the defense of the island of Oahu written in May, 1941:
"With adequate air defense enemy carriers, naval escorts and transports will begin to come under air attack at a distance of approximately 750 miles. This attack will increase in intensity until within 200 miles of the objective the enemy forces will be subject to attack by all types of bombardment closely supported by our most modern pursuit. ... Including the movement of aviation now in progress Hawaii will be defended by 35 of our most modern flying fortresses, 35 medium range bombers, 13 light bombers, 150 pursuit of which 105 are of our most modern type. In addition Hawaii is capable of reinforcement by heavy bombers from the mainland by air. With this force available a major attack against Oahu is considered impracticable.
In point of sequence, sabotage is first to be expected ..."
So, though reconnaissance flights were in place in July, 1941 out as far as 500 miles, when Dec. 7 arrived there were none to spot the six attacking Japanese aircraft carriers and the Chief of Staff's prediction was fantasy.
A surprisingly good section of this book deals with the unpreparedness of the Phillipines for attack, despite having 9 hours of warning after Pearl Harbor. Again, the attack was a surprise due to the failure of the commander, Gen. Douglas MacArthur, to conduct air reconnaissance of Formosa, from which the Japanese attack was launched.
A modern reader is likely to read the introduction and ask the same questions that the author does -- but concerning the 9/11 terror attacks on the World Trade Center. In fact, this book has had a resurgence in readership because Donald Rumsfeld recommended it highly to colleagues while serving as Secretary of Defense in the post-9/11 era.
And one of Rumsfeld's press conferences had him summarizing the issues for those reading intelligence signals :
"There are known knowns; there are things we know we know.
We also know there are known unknowns; that is to say, we know there are some things we do not know.
But there are also unknown unknowns – the ones we don’t know we don’t know."
Though Rumsfeld was mocked for the lack of clarity in that quotation, it is precisely this definition sought by he author in evaluating the information available just before the Pearl Harbor attack.
Wohlstetter looks at all of the evidence and much of the noise surrounding decision-making of key military and civilian leaders in the months leading up to December 7, 1941 and the attack on Pearl Harbor. She asks what information was present; what background noise might have obscured a message; and what assumptions were in place for key leaders.
The book is primarily based on the 39 volumes of the Congressional Hearings published in 1946, which is both a strength and a weakness. The hearings were detailed but held five years after the attack on Pearl Harbor when even the best memories had changed and key documents lost or destroyed. In addition, Wohlstetter ignores or misses some key elements, such as warnings at the end of January, 1941 from Joseph Grew, the American ambassador to Japan, that the Japanese were planning an attack on Pearl Harbor.
But it is a valuable piece of research, bringing together a large number of pieces of evidence and all of the key players. There are surprises for even those readers very familiar with the story of the American entry into World War II, including Gen. George Marshall's description of the defense of the island of Oahu written in May, 1941:
"With adequate air defense enemy carriers, naval escorts and transports will begin to come under air attack at a distance of approximately 750 miles. This attack will increase in intensity until within 200 miles of the objective the enemy forces will be subject to attack by all types of bombardment closely supported by our most modern pursuit. ... Including the movement of aviation now in progress Hawaii will be defended by 35 of our most modern flying fortresses, 35 medium range bombers, 13 light bombers, 150 pursuit of which 105 are of our most modern type. In addition Hawaii is capable of reinforcement by heavy bombers from the mainland by air. With this force available a major attack against Oahu is considered impracticable.
In point of sequence, sabotage is first to be expected ..."
So, though reconnaissance flights were in place in July, 1941 out as far as 500 miles, when Dec. 7 arrived there were none to spot the six attacking Japanese aircraft carriers and the Chief of Staff's prediction was fantasy.
A surprisingly good section of this book deals with the unpreparedness of the Phillipines for attack, despite having 9 hours of warning after Pearl Harbor. Again, the attack was a surprise due to the failure of the commander, Gen. Douglas MacArthur, to conduct air reconnaissance of Formosa, from which the Japanese attack was launched.
May 14, 2008
Pearl Harbor: Warning and Decision is an extremely well-written historical snapshot that utilizes the available secondary sources on one of the most devastating attacks in U.S. history. Wohlstetter utilizes a remarkable amount of available sources to comprise a look back on the Pearl Harbor attack only twenty years after its occurrence. She concludes that the pieces available to those in positions to anticipate or deter an attack were too decentralized for any administrative body to make a coherent recommendation. Implicit in this argument is that Pearl Harbor prompted the wholesale restructuring of the U.S. intelligence services. She concludes that warnings of surprise attacks remain ambiguous and uncertain, and this reality is unlikely to change. Nevertheless, pursuing perfect information in intelligence is a goal worth striving for if American is to have any chance of correctly anticipating a surprise attack.
Wohlestetter shows that many American politicians and military leaders understood that the possible repercussions of its oil embargo against the Japanese empire in 1941. Most of these leaders anticipated either an attack of sabotage on Oahu or a more likely surprise attack elsewhere in the Pacific, not at Pearl Harbor. Wohlstetter’s also devotes much of her book to revealing the motivations for policies on both sides of the Pacific. Japan seemed unable to hold back on its territorial land and sea grab in the face of national honor. America, conversely, was unable to divert its attention away from the European theater long enough to consider an outright attack on Hawai’i. Finally, Wohlstetter shows Japanese estimates of American forces and explains the rationale for attacking the then dormant American military machine. Japan hopes that coordinated attacks throughout the Pacific would deter a full scale retaliation by American forces.
Pearl Harbor was not the only notable surprise attack of 1941. That year Nazi forces invaded the Soviet Union. Blatantly defying a non-aggression pact, Hitler hoped that his surprise attack would give him an advantage over history—as in Napoleon’s famed retreat from the Russian winter. This miscalculation decimated Napoleon’s forces and marked the beginning of the end for the French emperor. Hitler’s army would meet a similar fate despite the German dictator’s obvious technical advantages. Comparisons between Japan’s surprise attack on Pearl Harbor and Hitler’s invasion are notable. Since both the United States and the U.S.S.R. would endure these military attacks and ultimately be victorious, historians should note similarities between these two invasions. The most obvious similarity comes from the ideas of Alfred Mahan, who noted with certainty that global hegemony could never be attained due to geographic realities. In short, distances can dictate military victors. Of course technology may shorten such distances, but to maintain a military presence over vast stretches of land or sea are difficult endeavors. Both the United States and the U.S.S.R. had (and still enjoy) these distances which make any full scale invasion difficult.
Scholars of the post-9/11 era should revisit Wohlstetter’s book on America’s (first) most devastating surprise attack. Of course, since the 1940s U.S. intelligence capabilities have increased considerably. Technology has aided in America’s never-ending quest for better intelligence, and the consolidation and corporatization of the U.S. intelligence agencies improves effectiveness. The temporary backlash and wariness of the CIA in the 1970s has since given way to an even more bureaucratized Department of Homeland Security after 9/11. It seems that with every surprise attack the need for fluidity of information across departments increases. Pearl Harbor differs from America’s intelligence challenges today. The United States currently battles not an empire, but an ideological foe, a scenario that arguably the Cold War has prepared America well. In short, contemporary readers can read Wohlstetter’s book today and note that even with technological advances and managerial restructuring in the field of intelligence, it seems that when it comes to intelligence, the more things change the more things stay the same.
Wohlestetter shows that many American politicians and military leaders understood that the possible repercussions of its oil embargo against the Japanese empire in 1941. Most of these leaders anticipated either an attack of sabotage on Oahu or a more likely surprise attack elsewhere in the Pacific, not at Pearl Harbor. Wohlstetter’s also devotes much of her book to revealing the motivations for policies on both sides of the Pacific. Japan seemed unable to hold back on its territorial land and sea grab in the face of national honor. America, conversely, was unable to divert its attention away from the European theater long enough to consider an outright attack on Hawai’i. Finally, Wohlstetter shows Japanese estimates of American forces and explains the rationale for attacking the then dormant American military machine. Japan hopes that coordinated attacks throughout the Pacific would deter a full scale retaliation by American forces.
Pearl Harbor was not the only notable surprise attack of 1941. That year Nazi forces invaded the Soviet Union. Blatantly defying a non-aggression pact, Hitler hoped that his surprise attack would give him an advantage over history—as in Napoleon’s famed retreat from the Russian winter. This miscalculation decimated Napoleon’s forces and marked the beginning of the end for the French emperor. Hitler’s army would meet a similar fate despite the German dictator’s obvious technical advantages. Comparisons between Japan’s surprise attack on Pearl Harbor and Hitler’s invasion are notable. Since both the United States and the U.S.S.R. would endure these military attacks and ultimately be victorious, historians should note similarities between these two invasions. The most obvious similarity comes from the ideas of Alfred Mahan, who noted with certainty that global hegemony could never be attained due to geographic realities. In short, distances can dictate military victors. Of course technology may shorten such distances, but to maintain a military presence over vast stretches of land or sea are difficult endeavors. Both the United States and the U.S.S.R. had (and still enjoy) these distances which make any full scale invasion difficult.
Scholars of the post-9/11 era should revisit Wohlstetter’s book on America’s (first) most devastating surprise attack. Of course, since the 1940s U.S. intelligence capabilities have increased considerably. Technology has aided in America’s never-ending quest for better intelligence, and the consolidation and corporatization of the U.S. intelligence agencies improves effectiveness. The temporary backlash and wariness of the CIA in the 1970s has since given way to an even more bureaucratized Department of Homeland Security after 9/11. It seems that with every surprise attack the need for fluidity of information across departments increases. Pearl Harbor differs from America’s intelligence challenges today. The United States currently battles not an empire, but an ideological foe, a scenario that arguably the Cold War has prepared America well. In short, contemporary readers can read Wohlstetter’s book today and note that even with technological advances and managerial restructuring in the field of intelligence, it seems that when it comes to intelligence, the more things change the more things stay the same.
November 28, 2024
This book is a groundbreaking study in the difficulties of intelligence analysis and surprise in war. It was immensely influential when it was written and is still the standard work on this subject.
That said, it is not easy reading. This book is very dense and took a lot of work to get through, but it should be required reading for anybody seriously interested in the attack on Pearl Harbour and anyone wanting to learn about how intelligence is collected, deciphered, transmitted, interpreted, and applied.
Wohlstetter introduces the concept of noise, which is a major contribution to our understanding of the problems that a nation's intelligence network faces in attempting to deduce what the enemy is going to do.
It is clearly demonstrated in these pages that the idea of an attack on Pearl Harbour being known by the US Government beforehand is based on simplified restrospective analysis. It is David Hackett Fischer's classic example of the Historian's Fallacy.
Wohlstetter implies that there were signals directing us towards the reality of an attack, but they're only obvious in hindsight because they are like finding needles in a haystack. The problem was that the US Government was bombarded by so much irrelevant 'noise' that the true signals were buried.
Among these contradictory signals were things like attacks on Thailand, on the British in Malaya, on the Dutch in Indonesia, on the Russians in Siberia, further offensives against China, an attack on the Philippines, on the Panama Canal, or any combination of these.
Particularly the focus was on a Japanese offensive along the Amur, which the US Army and Navy were especially convinced of, following Germany's invasion of the Soviet Union in June 1941.
Interestingly the Japanese seriously considered this option, but ultimately ruled against it. Yet the lingering rumour proved to be extremely useful, if serendipitous, misdirection.
Compounding this difficulty was the complicated chain of command and the less than perfect communication between the service branches, and between the men in Washington and those in Hawaii. Wohlstetter stresses here that the theatre commanders interpreted the various warnings to be against internal sabotage, not against external attack.
Japan compounded these difficulties by choosing to set out from Hitokappu Bay in the Kuriles, maintaining strict radio silence and giving the impression that the Japanese carriers were still in home waters.
ONI thought that the carriers were either in Japan or in the Mandates, and did not even consider them to be moving towards Hawaii. Movements south were similarly disguised by feints against Kunming in China, which succeeded in taking the British by surprise in Malaya.
There is far more to this story than a few paragraphs can hope to explain, but a few highlights for me were the American complacency based on presumed enemy capabilities, and the continued surprise even after Pearl.
As an example of the Psychologist's Fallacy the Americans weighed the relative power potential of the US and Japan and concluded, as the Japanese did also, that the US was immensely more powerful than Japan. The Americans believed that logically and rationally the Japanese would not start a war with the US. They were, in fact, more afraid of the Japanese attacking the British or Dutch and leaving the US with the uncomfortable conundrum of finding an excuse to intervene.
But they were obviously wrong, they had failed to truly understand the mentality of the Japanese. Japan proved more willing to take the risk of war than the Americans had anticipated, and to take the war directly against the United States instead of sidestepping them to the south.
In terms of technical capabilities the US Navy was confident that the depth of water at Pearl was too shallow for air-dropped torpedoes. They noted that the British attack at Taranto, often cited as a precursor to Pearl Harbour, was done in some ninety feet of water, whereas Pearl had only about thirty feet.
For this reason they believed that the Japanese could not possibly destroy the fleet from the air, as US intelligence, even Magic, had failed to glean the fact that this problem was solved by Japanese naval engineers.
The most interesting part is the surprise on the Philippines as an adjunct to the main question. MacArthur had taken preparations to face Japanese hostilities by moving his bombers out of harm's way, but this was done in leisurely fashion, which gives one an idea of what a full alert would have meant at Pearl.
Part of the reason for this was because the intelligence MacArthur's HQ possessed was deceived by all kinds of confusing signals. The signal that Pearl Harbour had actually been attacked let him know that Japan and the United States were at war, but that by no means meant that it indicated an attack on the Philippines.
For one thing the Americans did not know that the Japanese had, like their torpedo problem, solved the issue of aircraft range so that they could hit Clark and Nichols Fields directly from Taiwan. The Americans assumed that to do this they would need carriers, and since all the carriers had been at Pearl, they believed it was impossible.
Even when the planes struck the American aircraft on the ground, MacArthur and his staff still believed they must have come from carriers. This is very illuminating because it shows that even if some civilian like Hull or Roosevelt believed the attack on Pearl was imminent, the professional naval officers would have argued that it could not have been done.
All of them, from Stark, to Kimmel, to Marshall, to G-2 and ONI and the Naval War Plans Division were taken completely by surprise even despite the fact that war games held during the Fleet Problems had showed it was possible.
Even despite the fact that there were signals indicating an attack on Pearl, including a particularly interesting and shady one delivered through the US Embassy in Peru. Since this source was not seriously considered as credible it was, understandably, dismissed. It was evidently from a Japanese cook, but it was right.
This sheds much light on the nature of strategic surprise in general, which has by no means been confined to Pearl Harbour. Strategic surprise has been repeatedly achieved throughout the last century and has almost always succeeded. Even when there were direct indications of imminent attack.
As another example MacArthur's HQ in Tokyo, according to Gye-Dong Kim, received a direct signal in March 1950 stating that the North Korean Army would invade South Korea in June. MacArthur passed this on to Washington but added that he doubted it because he had received several such warnings that amounted to nothing, the Cry-Wolf Syndrome, and because he believed that North Korea would prefer to use subversive methods. Thus when North Korea crossed the 38th Parallel the United States was still taken by surprise even though it had received explicit warning two months before.
In my mind this further diminishes the case of a conspiracy, because strategic surprise was achieved over and over again all over the world but this one time the US Government knew of it? Seems unlikely.
In another review I had used the analogy of a detective novel, which involves similar contradictory signals and 'noise,' to distract our attention from the real culprit even though the clues leading to him were there all along.
Similar to how it becomes obvious once we reach the end and find out who the culprit is, and we realise what signals were genuine and which were ambiguous and misleading, so it is with surprise attacks. It is obvious in hindsight which signals were indicating an attack on Pearl Harbour, but at the time these were just a few among many other signals pointing in a kaleidoscope of other directions.
It would have taken superhuman perception to identify which were the genuine signals and what was the chaff.
That said, it is not easy reading. This book is very dense and took a lot of work to get through, but it should be required reading for anybody seriously interested in the attack on Pearl Harbour and anyone wanting to learn about how intelligence is collected, deciphered, transmitted, interpreted, and applied.
Wohlstetter introduces the concept of noise, which is a major contribution to our understanding of the problems that a nation's intelligence network faces in attempting to deduce what the enemy is going to do.
It is clearly demonstrated in these pages that the idea of an attack on Pearl Harbour being known by the US Government beforehand is based on simplified restrospective analysis. It is David Hackett Fischer's classic example of the Historian's Fallacy.
Wohlstetter implies that there were signals directing us towards the reality of an attack, but they're only obvious in hindsight because they are like finding needles in a haystack. The problem was that the US Government was bombarded by so much irrelevant 'noise' that the true signals were buried.
Among these contradictory signals were things like attacks on Thailand, on the British in Malaya, on the Dutch in Indonesia, on the Russians in Siberia, further offensives against China, an attack on the Philippines, on the Panama Canal, or any combination of these.
Particularly the focus was on a Japanese offensive along the Amur, which the US Army and Navy were especially convinced of, following Germany's invasion of the Soviet Union in June 1941.
Interestingly the Japanese seriously considered this option, but ultimately ruled against it. Yet the lingering rumour proved to be extremely useful, if serendipitous, misdirection.
Compounding this difficulty was the complicated chain of command and the less than perfect communication between the service branches, and between the men in Washington and those in Hawaii. Wohlstetter stresses here that the theatre commanders interpreted the various warnings to be against internal sabotage, not against external attack.
Japan compounded these difficulties by choosing to set out from Hitokappu Bay in the Kuriles, maintaining strict radio silence and giving the impression that the Japanese carriers were still in home waters.
ONI thought that the carriers were either in Japan or in the Mandates, and did not even consider them to be moving towards Hawaii. Movements south were similarly disguised by feints against Kunming in China, which succeeded in taking the British by surprise in Malaya.
There is far more to this story than a few paragraphs can hope to explain, but a few highlights for me were the American complacency based on presumed enemy capabilities, and the continued surprise even after Pearl.
As an example of the Psychologist's Fallacy the Americans weighed the relative power potential of the US and Japan and concluded, as the Japanese did also, that the US was immensely more powerful than Japan. The Americans believed that logically and rationally the Japanese would not start a war with the US. They were, in fact, more afraid of the Japanese attacking the British or Dutch and leaving the US with the uncomfortable conundrum of finding an excuse to intervene.
But they were obviously wrong, they had failed to truly understand the mentality of the Japanese. Japan proved more willing to take the risk of war than the Americans had anticipated, and to take the war directly against the United States instead of sidestepping them to the south.
In terms of technical capabilities the US Navy was confident that the depth of water at Pearl was too shallow for air-dropped torpedoes. They noted that the British attack at Taranto, often cited as a precursor to Pearl Harbour, was done in some ninety feet of water, whereas Pearl had only about thirty feet.
For this reason they believed that the Japanese could not possibly destroy the fleet from the air, as US intelligence, even Magic, had failed to glean the fact that this problem was solved by Japanese naval engineers.
The most interesting part is the surprise on the Philippines as an adjunct to the main question. MacArthur had taken preparations to face Japanese hostilities by moving his bombers out of harm's way, but this was done in leisurely fashion, which gives one an idea of what a full alert would have meant at Pearl.
Part of the reason for this was because the intelligence MacArthur's HQ possessed was deceived by all kinds of confusing signals. The signal that Pearl Harbour had actually been attacked let him know that Japan and the United States were at war, but that by no means meant that it indicated an attack on the Philippines.
For one thing the Americans did not know that the Japanese had, like their torpedo problem, solved the issue of aircraft range so that they could hit Clark and Nichols Fields directly from Taiwan. The Americans assumed that to do this they would need carriers, and since all the carriers had been at Pearl, they believed it was impossible.
Even when the planes struck the American aircraft on the ground, MacArthur and his staff still believed they must have come from carriers. This is very illuminating because it shows that even if some civilian like Hull or Roosevelt believed the attack on Pearl was imminent, the professional naval officers would have argued that it could not have been done.
All of them, from Stark, to Kimmel, to Marshall, to G-2 and ONI and the Naval War Plans Division were taken completely by surprise even despite the fact that war games held during the Fleet Problems had showed it was possible.
Even despite the fact that there were signals indicating an attack on Pearl, including a particularly interesting and shady one delivered through the US Embassy in Peru. Since this source was not seriously considered as credible it was, understandably, dismissed. It was evidently from a Japanese cook, but it was right.
This sheds much light on the nature of strategic surprise in general, which has by no means been confined to Pearl Harbour. Strategic surprise has been repeatedly achieved throughout the last century and has almost always succeeded. Even when there were direct indications of imminent attack.
As another example MacArthur's HQ in Tokyo, according to Gye-Dong Kim, received a direct signal in March 1950 stating that the North Korean Army would invade South Korea in June. MacArthur passed this on to Washington but added that he doubted it because he had received several such warnings that amounted to nothing, the Cry-Wolf Syndrome, and because he believed that North Korea would prefer to use subversive methods. Thus when North Korea crossed the 38th Parallel the United States was still taken by surprise even though it had received explicit warning two months before.
In my mind this further diminishes the case of a conspiracy, because strategic surprise was achieved over and over again all over the world but this one time the US Government knew of it? Seems unlikely.
In another review I had used the analogy of a detective novel, which involves similar contradictory signals and 'noise,' to distract our attention from the real culprit even though the clues leading to him were there all along.
Similar to how it becomes obvious once we reach the end and find out who the culprit is, and we realise what signals were genuine and which were ambiguous and misleading, so it is with surprise attacks. It is obvious in hindsight which signals were indicating an attack on Pearl Harbour, but at the time these were just a few among many other signals pointing in a kaleidoscope of other directions.
It would have taken superhuman perception to identify which were the genuine signals and what was the chaff.
March 2, 2025
3.5 ⭐️
to-keep-reference
May 27, 2022La explicación de Roberta Wohlstetter en contra de las teorías de la «conspiración» de por qué Estados Unidos no actuó, con base en las pruebas que tenía de un inminente ataque japonés a Pearl Harbor.
Anarquía, Estado y utopía Pág.20
Comentado en La señal y el ruido pág.549
Anarquía, Estado y utopía Pág.20
Comentado en La señal y el ruido pág.549
July 21, 2025
"Surprise, when it happens to government, is likely to be a complicated, diffuse, bureaucrtic thing."
#bookrecommendation from an #emergencymanagement #booknerd
It’s easy to view Pearl Harbor as a catastrophic mistake, but in reality, it was a typical failure—an inability of a well-informed government to foresee the enemy’s next move during a tense international situation. While the attack’s consequences were swift and severe, the errors leading up to it unfolded slowly and were all too familiar.
There was neglect of responsibility, unclear roles, misaligned authority, confusion in delegation, and a focus on distractions instead of recognizing the obvious warning signs. This illustrates that surprise attacks, whether at Pearl Harbor, 9/11, a power grid failure, climate change, pandemics or whatever, reflect a government’s failure to predict threats.
Pearl Harbor: Warning and Decision sheds light on this national failure to anticipate, revealing how easily complacency can take hold. The real threat today isn’t a lack of ability to interpret signals, but rather that leadership often focuses too narrowly on familiar, unlikely risks. Governments tend to oversimplify threats, but professionals in #emergencymanagement and #publicsafety must consider a wider range of potential risks and probabilities. Wohlstetter demonstrates how the complex and bustling nature of government can contribute to this issue.
From my perspective, especially as someone who has long advocated for change, Wohlstetter’s insights resonate deeply. Too many people are distracted by noise rather than searching for the real signals of danger. This leads to imbalanced spending and widening vulnerabilities. Without a unified understanding of the threats we face, we will never move forward together as a nation.
Additionally, we must confront the fact that certainty is elusive. We have to embrace uncertainty and learn to operate within it. No plan or data can offer absolute certainty, but our strategies must work despite it.
We must #changethewaywethink and do better for tomorrow.
#bookrecommendation from an #emergencymanagement #booknerd
It’s easy to view Pearl Harbor as a catastrophic mistake, but in reality, it was a typical failure—an inability of a well-informed government to foresee the enemy’s next move during a tense international situation. While the attack’s consequences were swift and severe, the errors leading up to it unfolded slowly and were all too familiar.
There was neglect of responsibility, unclear roles, misaligned authority, confusion in delegation, and a focus on distractions instead of recognizing the obvious warning signs. This illustrates that surprise attacks, whether at Pearl Harbor, 9/11, a power grid failure, climate change, pandemics or whatever, reflect a government’s failure to predict threats.
Pearl Harbor: Warning and Decision sheds light on this national failure to anticipate, revealing how easily complacency can take hold. The real threat today isn’t a lack of ability to interpret signals, but rather that leadership often focuses too narrowly on familiar, unlikely risks. Governments tend to oversimplify threats, but professionals in #emergencymanagement and #publicsafety must consider a wider range of potential risks and probabilities. Wohlstetter demonstrates how the complex and bustling nature of government can contribute to this issue.
From my perspective, especially as someone who has long advocated for change, Wohlstetter’s insights resonate deeply. Too many people are distracted by noise rather than searching for the real signals of danger. This leads to imbalanced spending and widening vulnerabilities. Without a unified understanding of the threats we face, we will never move forward together as a nation.
Additionally, we must confront the fact that certainty is elusive. We have to embrace uncertainty and learn to operate within it. No plan or data can offer absolute certainty, but our strategies must work despite it.
We must #changethewaywethink and do better for tomorrow.
May 24, 2021
Very detailed history of the surprise attack on Pearl Harbor and the events leading up to it. It was fascinating to read and had some profound insights. Key takeaway is that we cannot rely on receiving strategic warning. That being said, it was dry reading at times and took me awhile to work my way through it. I do recommend though!
July 31, 2024
A good read for the Washington Policy and where the Army and Navy went wrong. Although it seems it was still very hard to predict, as no MAGIC signals that were picked up and translated mentioned the attack on pearl harbour.
Lots of dates and people, can be a bit slow. I am interested to read 'a day of infamy' instead. Nothing on the Japenese Spy present in pesrl harbour.
Lots of dates and people, can be a bit slow. I am interested to read 'a day of infamy' instead. Nothing on the Japenese Spy present in pesrl harbour.
October 12, 2022
A masterful study of complexity and contingency. Wohlstetter’s account of the overwrought but under-communicated intelligence system in place on December 7 and how it could not distinguish signals amidst the noise because of its poverty of expectations remains a classic 60 years later.
September 29, 2024
The material is a little dry, but very insightful and I'd consider this to be one of the best authoritative sources for information about the United States-held intelligence ahead of the Japanese attack on Pearl Harbor, and why the U.S. did not better defend itself from that attack.
July 14, 2021
Epic…so many details it was a bit confusing
September 1, 2022
intriguing piece of historical analysis. Wohlstetter is thorough and enlightening.
August 9, 2016
Alerts in June 1940, July and October 1941, and 27 November 1941. November - Short was advised to expect "hostile action" at any moment. but - hostile action: sabotage? subversion? attack against Russia? Britain? the Dutch? American possessions? if so, which? What actions should the commanders make ready in response? The three previous alerts created noise, obscuring the warning of the final signals. Limited distribution of intelligence, no knowledge of who had what intelligence, changing static intelligence, army vs navy estimates, slow communications, Washington assuming that theaters had comparable newspaper coverage available, advice rather than explicit orders given while withholding perinatal information, no acknowledgement required of messages, or follow-up on what had been implemented. Fixation on the expected.
December 5, 2014
Outstanding account of why the US was surprised by the Japanese attack on Pearl Harbor, and a consideration of the implications for our ability to defend against a surprise nuclear attack. Her prescient conclusion, "If the study of Pearl Harbor has anything to offer the future, it is this: We have to accept the fact of uncertainty and learn to live with it. No magic, in code or otherwise, will provide certainty. Our plans must work without it." Really, I cannot imagine a more reasoned and insightful book on intelligence analysis.
December 15, 2016
Very informative and interesting with multitudes of specific information about the intelligence picture leading up to the war with Japan and specifically the Pearl Harbor attack. Great analysis of it as well. It is a very dense, dry, and academic book despite also being interesting, which made it especially slow for me to get through.
February 28, 2016
As I remember it, the book is a classic. Far from weaving conspiracy theories, the author portrays the inability to break through the "noise" of the knowledge that we did have.
April 23, 2015
great historical account. not the right book for the start of my Hawaiian vacation but sure informed my trip to Pearl Harbor later in the week!
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