IBDP History IA Examples: Did FDR Know about Pearl Harbour in Advance?

 Did Franklin D. Roosevelt know of the Pearl Harbour attack before it happened?
. 8

Identification and evaluation of sources

When looking back at the events that led up to Pearl Harbour in 1941, it leaves us wondering whether the circumstances of the time were “too ideal” in allowing the USA to join the second world war. This would indicate that it may not have entirely been fate that made the Japanese bomb the United States naval base at Pearl Harbour leading to the question “Did Franklin D. Roosevelt know of Pearl Harbour before it happened?”. This investigation will look at the claims of the conspiracy theory where two of the main sources would be the McCollum Memo and Day of deceit by Robert Stinnett.  

Source 1[2]
Text Box: 9. It is not believed that in the present state of political opinion the United States government is capable of declaring war against Japan without more ado; and it is barely possible that vigorous action on our part might lead the Japanese to modify their attitude. Therefore, the following course of action is suggested: A. Make an arrangement with Britain for the use of British bases in the Pacific, particularly Singapore. B. Make an arrangement with Holland for the use of base facilities and acquisition of supplies in the Dutch East Indies. C. Give all possible aid to the Chinese government of Chiang-Kai-Shek. D. Send a division of long range heavy cruisers to the Orient, Philippines, or Singapore. E. Send two divisions of submarines to the Orient. F. Keep the main strength of the U.S. fleet now in the Pacific in the vicinity of the Hawaiian Islands. G. Insist that the Dutch refuse to grant Japanese demands for undue economic concessions, particularly oil. H. Completely embargo all U.S. trade with Japan, in collaboration with a similar embargo imposed by the British Empire.  10. If by these means Japan could be led to commit an overt act of war, so much the better. At all events we must be fully prepared to accept the threat of war.- H. McCollum

The origin of Source 1 is a memo, written by Arthur H. McCollum the year before the Pearl Harbour bombing. The origin is valuable when looking at the content, as Franklin D. Roosevelt was looking for an opportunity for the USA to enter the war so they needed to conjure a plan which would give them their needed opportunity. This is an important and valuable source due to it being a primary source that is taking place at the time of the second world war, which would give us an understanding of the events as it occurred and to what lengths the US government would go to. Also now with hindsight it becomes evident how great of a role this memo would have had in the United States’ entrance into World War 2. The purpose of this memo was to inform FDR how he could “le[a]d [Japan] to commit an overt act of war”. However, the limitation with this is that McCollum could not have known how large of an affect Pearl Harbour would have and how strongly the US would be hit. He only wanted a way for the US to get into the war and not the death of nearly 2,500 of his own people and a two front war with the Germans and the Japanese.

Source 2[3]
 Text Box: Despite his pleadings and persuasions, powerful isolationist forces prevented Roosevelt from getting into the European war. Roosevelt’s advisors included the American patriots such as General George Marshall, Rear Admiral Walter S. Anderson, and Commander Arthur H. McCollum who understood the need to arouse the United States from its isolated position. The wisdom and moral justification for the decision to provoke Japan into a bloody and terrible war that ultimately took millions of lives will be argued for many years by people of good faith and from all political persuasions.

The origin of Source 2 is a book called Day of Deceit, by Robert Stinnett, published in 1999, 58 years after Pearl Harbour took place. This is valuable as this source is able to see the event with hindsight, as classified government documents were made public in 1994 on this topic, giving Stinnett a new understanding that could not have been understood before. He points out how Roosevelt was prevented from joining the war and needed to provoke Japan in order for their isolated standpoint to be released, which is valuable when trying to understand this prior knowledge theory. On the other hand, the purpose of this source is to inform people of the claimed false history and that things weren’t as simple as they appeared to be. However, the limitation of this source is that Stinnett throws around a lot of allegations without much evidence and seems to ignore 10 years of Japanese aggression in the east and well as the fact that Roosevelt wanted to fight against Germany, and not a two front war.


“We will have to take a good many defeats before we can have a victory.”[4] The words uttered by Franklin D. Roosevelt to his wife upon hearing the news of the Pearl Harbour attack that would launch the United States into World War 2. It is claimed that the United States, in an attempt to enter the war, needed to provoke the Japanese into attacking them and use them as a scapegoat for their entrance. This investigation will examine whether through the McCollum memo, the US and FDR had prior knowledge of the Pearl Harbour attack by goading Japan into an attack, but that there is also limited evidence to support that this document, although created for the President, was ever seen by him. This is ultimately the predominant focus that would decide whether or not Franklin D. Roosevelt, the 32nd President of the United States knew of the Pearl Harbour attack before it occurred on the 7th December 1941 in order to join the Great War in Europe.

Since the declassification of the McCollum memo in 1994, new light has been shed upon the previously claimed surprise attack on the Pearl Harbour naval base. Within the memo, written by Arthur McCollum, it states his 9-point plan which “If by these means Japan could be led to commit an overt act of war, so much the better.”[5] This identifies the focal argument that in order for the US to join the war, they were required to find an entrance where they weren’t seen as the aggressor. This is exemplified by Harry E. Barnes who argues that;

“Roosevelt and Churchill had decided that it may be impossible for the United States to enter the war through by the European front door, and in August, 1941, they met off the coast of Newfoundland to devise a way whereby Roosevelt could force America into war through the backdoor of the Far East by a manipulation of Japanese-American relations.”[6]

This “backdoor of the Far East”[7] was America’s chance to join the war effort, but if carried our incorrectly, could lead them into fighting a much larger war than they could anticipate. Over the next few months, since the creation of the McCollum memo, the United States began to carry out the 9-point plan to lure the Japanese into an attack. For this memo and its points to have been carried out, it would have needed to have been seen and approved for it to go ahead by the President. Although there are no specific records which indicate that FDR had ever seen the McCollum memo, Robert Stinnett claims that “a series of secret presidential routing logs plus collateral intelligence information in the Navy files offer conclusive evidence that [FDR] did see it.”[8] Furthermore it is evident that that FDR saw the memo as he stated that he wanted pop-up cruises “to keep popping up here and there and keep the Japs guessing. I don't mind losing one or two cruisers, but do not take a chance on losing five or six.”[9] Which would support actions D, “Send a division of long range heavy cruisers to the Orient, Philippines, or Singapore.” and E, “Send two divisions of submarines to the Orient.”, of the memo[10]. All in all, the United States needed to enter the war but did not have an opportunity to do so, making the McCollum memo a necessary document that would aid FDR in entering a war to fight fascism in Europe.

However, the issue with the McCollum memo is that although there are assumptions that can be made to show that Franklin D. Roosevelt saw the memo, there is no real proof to support this assumption. According to James Rusbridger and Eric Nave, in their book Betrayal at Pearl Harbor published in 1991, it is claimed that the British had cracked the Japanese codes, where they were led to know of the Japanese intentions to attack Pearl Harbour.[11] There is credibility in the account by Rusbridger and Nave, as Eric Nave was the person who had cracked the Japanese naval cipher JN-25 in 1939, and Rusbridger, a member of MI6, was an expert on intelligence matters.[12] Their book claims that Winston Churchill had advance knowledge of the attack and refused to inform the President of the United States in order to drag the US into the Great War as their help was much needed and their entrance would be almost impossible if there was not to be an unprovoked attack on them by the enemy[13]. Although the account by Nave is speculated to be untrue, Eugene L. Rasor[14], Ian Pfenningwerth[15], Michael Smith[16], and Peter Donovan[17] all agree on his involvement in solving the Japanese naval cipher in 1939. Not only do they agree on this matter, but the fact, as expressed in Betrayal at Pearl Harbor, that Nave was able to intercept the cipher and solve it would be a sign of the allies having advanced knowledge of the attack upon Pearl Harbour, and in an attempt to win the war, withheld it for the Americans. The McCollum Memo’s purpose in this conspiracy is to indicate that Franklin D. Roosevelt had prior knowledge of the attack, but with Rusbridger’s argument, one can see that it would make sense for the British Intelligence to withhold information from Roosevelt as the act that was going to be committed by Japan would force the USA into the Second World War, giving Britain a greater chance of defeating the Nazis[18].

With the consideration of the McCollum Memo and Eric Nave’s code breaking, it can be determined that this topic is widely disputed amongst experts especially as it is a conspiracy theory with the ability to change the way that America’s entrance into the war could be seen. The actions that have been claimed against Roosevelt have implications for people on the wider scale, especially when referring to the Navy seals after the attack. It becomes apparent that the events after Pearl Harbour were very similar to occurrences in the world today, especially in respect to the intelligence agencies who look for scapegoats in order to improve a situation, where possible inside knowledge would lead to drastic consequences[19]. While the evidence from Betrayal at Pearl Harbor would lead to one assuming that Churchill had prior knowledge of the attack, James Rusbridge received his information from an elderly man writing over 50 years after the events occurred. Although the book is a fascinating read, it appears to be following William Stevenson’s style in A Man Called Interpid, where the reader appears to be delving into an imaginative story rather than a factual historical account[20]. The basis that this conspiracy theory has been written on simply appears to be, as most conspiracy theories do, filling in an area of history where there is a blank, and then finds loose bits of ‘evidence’ that are able to make the story make sense. This would lead one to be more inclined to believe that FDR or even Winston Churchill did not know about the Pearl Harbour attacks in advance. Even the McCollum Memo lacks significant evidence to support that it was ever shown to the President and was anything more than a report by Arthur McCollum, with little significance other than tying together the strings of a conspiracy theory.

In conclusion, it can be seen that there have been several attempts made to support the theory that Franklin D. Roosevelt knew of the Pearl Harbour attacks before it happened in order to join the war in Europe, but with little to no citations stated in the bibliographies other that the McCollum Memo, one would have to opt in favour of the real story due to the scarcity of sources on the topic being available. Although there are a few books that have been written on the conspiracy theory, they all seem to have three things in common; the McCollum Memo, a heroic story of one man’s incredible discovery of the Japanese intentions, and a lack of sources to back up the claims of the writers. This would all point towards the decision that FDR did not have prior knowledge of the Pearl Harbour attack in December 1941.


I knew that the only way to attempt to find reasons to support this conspiracy theory would be if I started from the beginning, where it all came from. The McCollum Memo was the document that Robert Stinnett and other writers on this topic based their theory more or less completely on and I knew that I had to research it in order to yield valuable results. The so called ‘historians’ on this topic based their investigation around the McCollum Memo and used loose bits of evidence of heroic stories in order to make their point heard.

The issue that I faced with the memo was that although it was an official US government document that assessed different ways of goading Japan into an attack, it lacked evidence to prove that FDR had even seen it. Other limitations were that a few of the books claimed that they had too many citations to put them in, making me question the broad range of claims and accusations that had been made without evidence to support it. Not only were there limited sources on this topic, but the heroic accounts of Eric Nave appeared to be rather fictional and over exaggerated in order to make the story fit with real hard facts. All of these issues limited the effectiveness of this investigation in finding a result to back the conspiracy theory because there simply is not enough information on the topic, and the evidence that is available lacks credibility or citations.

Writing in Germany, one has to feel that a historian writing on this conspiracy theory would have certain limitations. Especially with holocaust denial being such a taboo subject, how can other conspiracy theories, especially one with the importance of this one, be written about without facing certain ethical dilemmas depending on the country that it is being written in.

This investigation required me to rely on history and emotion, as to understand the historical accounts, one has to feel the emotion that the source is presenting and even though there is significant hyperbole in the writing, one has to overlook it to grasp what was really intended and use it as accurately as possible.

Overall, this investigation gave me a great opportunity to find out more on the subject that I have been so interested in discovering. I was able to use investigative skills to find evidence to support and counter the research question and ultimately I have discovered enough evidence to show that Roosevelt did not know about the Pearl Harbour attack before it happened.


Barnes, Harry Elmer. Perpetual war for perpetual peace: a critical examination of the foreign policy of Franklin Delano Roosevelt and its aftermath. Torrance, CA: Institute for Historical Review, 1982. Print.

Donovan, Peter. Code breaking in the pacific. S.l., Springer International PU, 2016. Print.

Goodwin, Doris Kearns. No ordinary time: Franklin and Eleanor Roosevelt: the home front in World War II. New York: Simon & Schuster, 2013. Print.

Layton, Edwin T. "And I was there". New York, William Morrow and Company, 1986. Print.

McCollum, A. McCollum Memo. Franklin D. Roosevelt, DC. 7 October 1940.
Stinnett, Robert B. Day of deceit: the truth about FDR and Pearl Harbor. New York, NY: Touchstone, 2004. Print.

PFENNIGWERTH, IAN. MAN OF INTELLIGENCE: the life of captain eric nave, code breaker extraordinary. S.l., READHOWYOUWANT COM LTD, 2012. Print.

Rusbridger, James, and Eric Nave. Betrayal at Pearl Harbor: how Churchill lured Roosevelt into World War II. London: Michael O'Mara, 1991. Print.

Schneider, Carl J., and Dorothy Schneider. World War II. New York, Facts On File, 2003. Print.

Smith, Michael. The emperors codes: the thrilling story of the allied code breakers who turned the tide of World War II. New York, Arcade Pub., 2011. Print.

Stevenson, William. “A man called Intrepid: the incredible WWII narrative of the hero whose spy network and secret diplomacy changed the course of history”. Guilford, CT, Lyons Press, 2000. Print

Stinnett, Robert B. Day of deceit: the truth about FDR and Pearl Harbor. New York, NY: Touchstone, 2004. Print.

The burning and damaged ships at Pearl Harbor. 1941. Historylink101.

[1] The burning and damaged ships at Pearl Harbor. 1941. Historylink101.
[2] McCollum, A.
[3] Stinnett, Robert B.
[4] Goodwin, Doris Kearns. P290
[5] McCollum, A.
[6] Barnes, Harry Elmer.
[7] Barnes, Harry Elmer.
[8] Stinnett, Robert B. P9
[9] Stinnett, Robert B. P9
[10] McCollum, A.
[11] Rusbridger, James, and Eric Nave. P227
[12] Rusbridger, James, and Eric Nave. P166
[13] Rusbridger, James, and Eric Nave. P151
[14] Rasor, Eugene L. P146
[15]Pfennigwerth, Ian. P277
[16] Smith, Michael.
[17] Donovan, Peter. P37
[18] Schneider, Carl J., and Dorothy Schneider. P183
[20] William, Stevenon.

 Old example using previous criteria

Did Roosevelt Have Advance Warning of Pearl Harbour?

Plan of Investigation
This investigation seeks to address the extent to which President Roosevelt and his commanding authorities had foreknowledge of the December 7th attack on Pearl Harbour, specifically in terms of advance warning and code breaking. If the cover-up was to be true, FDR would be directly responsible for 2403 deaths, 1178 wounded, 18ships and 350 planes[1] damaged by the war. Two of the main sources used in the essay which both represents the main school of thought, Day of deceit: The Truth about FDR and Pearl Harbour by Robert Stinnett and At Dawn We Slept: the Untold Story of Pearl Harbour by Gordon W. Prange are then evaluated for their origins, purposes, value and limitations.

B. Summary of Evidence
Chronology of events before the attack
1904- The Japanese destroyed the Russian navy in a surprise attack in
undeclared war.[i]
October 7 1940 –McCollum proposes the 8 point memo to President Roosevelt[ii]
11 February 1941 - FDR proposed sacrificing 6 cruisers and 2 carriers at Manila to get into war.[2][iii]

June 14 1941 – FDR learns about Germany’s plans for attacking the Soviet Union by means of a Purple intercept[iv]
November 5 1914 – Emperor Hirohito in an Imperial conference decided on war and Japan’s military was given the go-ahead for the conquest of Southeast Asia.[v]
December 6 1941 –- FDR makes a final appeal to the Emperor of Japan for peace. [vi]
Chronology of events during the attack on December, 7th 1941
Sunday, December 7 - Washington D.C. - The last part of the Japanese message, stating that diplomatic relations with the U.S. are to be broken off, reaches Washington in the morning and is decoded at approximately 9 a.m. About an hour later, another Japanese message is intercepted. It instructs the Japanese embassy to deliver the main message to the Americans at 1 p.m. The Americans realize this time corresponds with early morning time in Pearl Harbour, which is several hours behind. The U.S. War Department then sends out an alert but uses a commercial telegraph because radio contact with Hawaii is temporarily broken. Delays prevent the alert from arriving at headquarters in Oahu until noontime (Hawaii Time) four hours after the attack has already begun.
Sunday, December 7 - Islands of Hawaii, near Oahu - The Japanese attack force under the command of Admiral Nagumo, consisting of six carriers with 423 planes, is about to attack. At 6 a.m., the first attack wave of 183 Japanese planes takes off from the carriers located 230 miles north of Oahu and heads for the U.S. Pacific Fleet at Pearl Harbour.
Pearl Harbour - At 7:02 a.m., two Army operators at Oahu's northern shore radar station detect the Japanese air attack approaching and contact a junior officer who disregards their reports, thinking they are American B-17 planes which are expected in from the U.S. west coast.
Near Oahu - At 7:15 a.m., a second attack wave of 167 planes takes off from the Japanese carriers and heads for Pearl Harbour.
At 7:53 a.m., the first Japanese assault wave, with 51 'Val' dive bombers, 40 'Kate' torpedo bombers, 50 high level bombers and 43 'Zero' fighters, commences the attack with flight commander, Mitsuo Fuchida.
Chronology of events after the attach
Monday, December 8 - The United States and Britain declare war on Japan with President Roosevelt calling December 7 “a date which will live in infamy.”
Thursday, December 11 - Germany and Italy declare war on the United States. The European and Southeast Asian wars have now become a global conflict with the Axis powers; Japan, Germany and Italy, united against America, Britain, France, and their Allies.
Wednesday, December 17 - Admiral Chester W. Nimitz becomes the new commander of the U.S. Pacific Fleet.
Both senior commanders at Pearl Harbour, Navy Admiral Husband E. Kimmel, and Army Lt. General Walter C. Short, were relieved of their duties following the attack. Subsequent investigations will fault the men for failing to adopt adequate defence measures.

C. Evaluation of Sources

Day of Deceit: the Truth about FDR and Pearl Harbor by Robert Stinnett, a WWII naval veteran who served under Lt. George Bush, was the first revisionist to claim that President Roosevelt had foreknowledge of the attack on Pearl Harbor through decrypted Japanese naval messages. While Robert Stinnett himself claims his primary purpose as “to learn about the intercept procedures”[3] of the requested sources and to “disclose a story hidden from the public” which “should be told to the American people”[4], Library Journals claims it a book which “contemporary and classic Roosevelt haters would cherish”. The book’s value lies in the fact of Stinnett’s 20 years of archival research through the Freedom of Information Act and interviews with surviving U.S. Navy cryptographers. Earning a 70 percent public approval rating, Day of Deceit continues among the top 10 best-sellers in the non-fiction Pearl Harbour book category, according to Amazon.com and Barnes & Noble.com[5]. Immediately after its appearance in bookstores in 1999, over two dozen NSA withdrawal notices triggered the removal of Pearl Harbour documents from public inspection. Nevertheless, as the New York Times states the book will probably “elicit sceptical responses from other historians”[6]. According to Robert Bernstein, Stinnett as a journalist who plays amateur historian with the fact that most participants of the war are dead and cannot defend themselves[7], may take a “dogged and sometimes compelling” attitude when substantiating his conclusion. Moreover, the book failed to take account of less drastic possible analysis for the data it has covered and to some extent may reflect contemporary anti-government sentiment.

Whereas Day of Deceit was claimed to be “skeptical”, At Dawn We Slept: the Untold Story of Pearl Harbour is the first and most important volume, covering nearly the entire 12-month period leading up to the "day of infamy" that marked America's entry into World War II. It provides insights into both Japanese and American mindsets while attacking revisionists' views that Japan's attack succeeded because President Franklin D. Roosevelt withheld critical information from Army and navy commanders in Hawaii. Value of this book can be seen, as Prange was a military historian on MacArthur's staff who researched for military and government documents of both sides that participated in the war and interviewed key people involving Pearl Harbour for 37 years prior to his death. He never finished this book, leaving his collaborators Goldstein and Dillon to finish the book, so this is a composite production. The author is fair and presents the facts in a manner that allows the reader to draw his or her own conclusions. However, while the greatest strength of this book is the extensive Japanese information and interviews, those who had the greatest knowledge were almost all killed during the war or in the war crimes trials shortly thereafter. As well, the book lacks essential information, some of which only become available recently, with other material still locked up. Much was destroyed or disappeared at the orders of the accusers of General Short and Admiral Kimmel, the scapegoats. Therefore, some claimed that it should no longer be considered "definitive" or "authoritative."
D. Analysis
For nearly 60 years it had been bruited about, and for nearly 60 years unproved[8]. Revisionist historians have long argued that Roosevelt, by withholding critical information from commanders in the field, wanted, as Stinnett puts it, to ''ensure an uncontested overt Japanese act of war.''[9] Given that 2,273 American soldiers and sailors died at Pearl Harbour[10], this conclusion, if proven to be correct, would require some drastic rethinking about Roosevelt and the American entry into the war.

Historians of World War II generally agree that Roosevelt believed war with Japan was inevitable and that he wanted Japan to fire the first shot[11]. Yet, revisionist historians tend to demonstrate that to ensure that the first shot would have a traumatic effect, Roosevelt intentionally left Americans defenceless.

Stinnett’s view in the book focusses on three main points:

1.     McCollum Memo
One of the the centrepieces of Stinnett’s argument is an October 7, 1940 memorandum by Lieutenant Commander McCollum of ONI to Navy Captains Walter Anderson and Dudley Knox, which details eight actions which might have the effect of provoking Japan into attacking the United States. The memo was only classified until 1994. Sections 9 and 10 of the memo are cited as the "Smoking Gun", a line was written that “If by these means Japan could be led to commit an overt act of war, so much the better. At all events we must be fully prepared to accept the threat of war.” A primary thesis of Stinnett’s book suggests that the memorandum was central to the high level conspiracy to lure the Japanese into an attack and that it actually reached President Roosevelt, senior administration officials, or the highest levels of US Navy command.
However, orthodox historians claim that such misinterpretation exaggerated the impact of McCollum's memo and assuming Germany was bound to declare war on the United States once Japan did. The memo suggests that only a direct attack on U.S. interests would sway the American public or Congress to favour direct involvement in the European war, specifically in support of the British. An attack by Japan would not, could not, do that as history has proved. Stinnett improperly ascribes McCollum's office as "an element of Station US, a secret American cryptographic center located at the main naval headquarters" as a meaning of OP-20-G in an effort to tie McCollum closer to OP-20-G than he actually was before WW2. Furthermore, according to Stinnett, among the eight actions offered in the, only one was ever implemented in any fashion, and there is considerable doubt the memo was the inspiration. Nonetheless, as shown in Day of Deceit, Stinnett claims all action items were implemented. Lastly, although the memo was passed to Captains Walter Anderson and Dudley Knox, two of Roosevelt's military advisors, on October 7, 1940, there is no evidence available to suggest Roosevelt ever saw it, nor any he did not.

2.     Diplomatic Codes
“The most explosive controversy involving America’s foreknowledge of Japan’s attack on pearl harbor,” Robert Stinnett has written, “involved the Kaigun Ango [Navy code], a complex matrix of twenty-nine separate codes.”[12] To assemble and dispatch the first Air Fleet to Hawaii by radio, the Japanese Navy used four of these separate codes. By the fall of 1914, U.S. cartographers had solved them all.[13] A sixty-year cover-up has hidden American and Allied success in obtaining the solutions of the Kaigun Ango prior to Pearl Harbor.[14] “Naval intelligence records, deceptively altered, were places in the US Navy’s cryptology files to hide the cryptographic success.”[15] Moreover, the last intercept of a message from Yamaoto to the First Air Fleet was on December 2. It read:” Climb niitakyama[16] 1280, repeat 1280.” According to historian James Rusbridger, “(i)t hardly needed a code breaking genius to deduce that this was the date of the opening attack.”[17] This was the only radio message giving the date of the attack; previously, it had been mentioned only as Y-Day in the operational orders given to the First Air Fleet in Hitokappu Bay before it got underway.

Though significant, for Budiansky this was also one of the “most disturbing and irrational” argument by confusing intercepts, codes, and decryptions. As well assured by Wedemeyer, Stinnett used the subterfuge of referring the two completely different versions of the Japanese main administrative naval code as only one "5-Num" code. Thus, he imputed the U. S. Navy's initial success with the earlier and simpler one-part code and cipher, JN-25A (AN), which was implemented on 1 June 1939, to the much more complicated two-part code and cipher combination with a much larger dictionary of about 50,000 code values (by use of auxiliary tables) and a larger cipher additive book of JN-25B (AN-1) in effect at the time of Pearl Harbour[18], whereas the fact that JN-25B (AN-1) replaced JN-25A (AN) on 1 December 1940 was skimmed over.

E. Conclusion
It is difficult, after reading a whole bevy of suspicions and allegations thrown out by the revisionists, not to wonder at the "possibility" that U. S. had decrypted a substantial number of key JN-25B messages which gave a questionable forewarning of the planned attack on Pearl Harbour and that such "foreknowledge" was intentionally withheld to incite US into war.

However, the failure to take into account other, less drastic possible analyses and interpretations outweighed the assumption. Though interesting, the conspiracy theory shows a strong dose of scepticism.
Within the few decades, the holocaust denial, the 9/11 truth and the John F. Kennedy assassination have been dredged up. Pearl Harbour provides a less urgent lesson. The disaster there needs to be remembered, not for anything about Japanese treachery or U.S blunders. Its main lessons are about sacrifice, deception and political considerations as common features of military planning.
The sense of duty and regard for human life of President Roosevelt and his chief advisers should be understood. After all, so wrote the immutable warrior Winston Churchill: “No American will think it wrong of me if I proclaim that to have the United States in war on our side was to be the greatest joy…”[19]

F. List of Sources
Carew, Michael G. The Power to Persuade: FDR, the Newsmagazines, and Going to War, 1931-1941. Unites States of America: University Press of America, 2005
Garrarty, John A. A Short History of the American Nation. Addison Wesley Educational Publisher Inc, 1987 Heardon, Patrick J. Roosevelt Confronts Hitler: America’s Entry into World War II. Northern Illinois University Press 1987 Jenkins, Roy. Franklin Delano Roosevelt. New York: Pan books, 2003 Odo,Franklin. No Sword to Bury: Japanese Americans in Hawaii during World War II. Philadelphia:Temple University Press, 2004 Prange, Gordon W. At Dawn We Slept: The Untold Story of Pearl Harbour.  USA: Penguin, 1982 Ross, Stewart Halsely. How Roosevelt failed America in World War II. Mcfarland & Company: United States, 2006 Stinnett Robert. Day of deceit: The Truth about FDR and Pearl Harbour. Free Press 2000 Toland, John. Infamy: Pearl Harbor and its aftermath. New York: Berkley, 1986 The Rising Sun: The Decline and Fall of Japanese Empire, 1936-1945. New York: Random House, 1970 Victor, George. The Pearl Harbor Myth: Rethinking the Unthinkable. United States of America: Potomac Books, 2007 Wood, Edward W. Worshipping the Myths of World War II: Reflections on America’s declaration to war. Potomac books: Washington D.C, 2006 Yardley, Herbert O. The American Black Chamber. USA: Aegean Park Press, 1989
[1] Daniel J. McINERNEY. A Traveler’s History of the USA.2001.New York Interlink Books  [2] (Charles Beard PRESIDENT ROOSEVELT AND THE COMING OF WAR 1941, p 424  [3] Douglas Cirignano (March 11, 2002). Interview with Robert B. Stinnett - Do Freedom of Information Act Files Prove FDR Had Foreknowledge of Pearl Harbor?  [4] Stinnett, 412  [5] Stinnett (December 7, 2003). The Pearl Harbor Deception Independent Institute  [6] Richard Bernstein (December 15, 1999). Books of the Times: On Dec. 7, Did We Know We Knew? New York Times.  [7] Philip H. Jacobsen: A Cryptologic Veteran's Analysis of Day of Deceit  [8]  [9] Stinnett, 23  [10] Ross 75  [11] Wood, 134  [12] Stinnett, 30  [13] Ross, 68  [14] Stinnett, 69  [15] Stinnett, 71  [16] Niitakyama is a 130,000 –foot peak in formosa, the highest mountain in what was then part of Japan. Scaling it was considered a siginificant mountaineering feat. Inthis instance it was final confirmation that the First Air flett should attack pearl Harbour.  [17] Rusbridger, 125  [18] Stinnett, 22-3, 47-52, 71-82, 204, 231  [19] Toland, The Rising Sun, 146

[i] The Battle of Port Arthur starting the Russo-Japanese War began with a surprise night attack by a squadron of Japanese destroyers on the Russian fleet anchored at Port Arthur, Manchuria, and continued with an engagement of major surface combatants the following morning. This case was similar to the attack on Pearl Harbor.

[ii] As the Head of the Far East desk of Office of Naval Intelligence, Lt. Commander Arthur H. proposed a secret U.S foreign policy initiative that called for goading Japan into an overt act of war against an isolationist United States.
[iii] Navy Chief Stark objected by claiming that "I have previously opposed this and you have concurred as to its unwisdom. Particularly do I recall your remark in a previous conference when Mr. Hull suggested [more forces to Manila] and the question arose as to getting them out and your 100% reply, from my standpoint, was that you might not mind losing one or two cruisers, but that you did not want to take a chance on losing 5 or 6."
[iv] Japan’s preparation for war took an ominous turn in July 1941. That was the month Roosevelt put into place the last of McCollum’s action items, Action H- a strangling embargo that was intended to provoke strong counterstrokes by Japan. Intercepts of Purple code transmissions throughout the summer revealed Japan’s reaction to FDR’s tightening of the economic screws: 500,000 Japanese citizens were inducted into the armed services; Japanese merchant ships from all over the world were recalled to home water; and Japanese warships and air squadrons were withdrawn from china. War clouds were gathering

[v] Specifically, Admiral Yamamoto was charged with smashing the Pacific Fleet in Pearl Harbor.

[vi] There is no reply. Late this same day, the U.S. code-breaking service begins intercepting a 14-part Japanese message and deciphers the first 13 parts, passing them on to the President and Secretary of State.