Presidential Conspiracy Theories: FDR and Advance Knowledge of the Attack on Pearl Harbor
Ever since the December 7, 1941 attack on Pearl Harbor, conspiracy theories have circulated claiming that President Franklin Delano Roosevelt knew that the attack was coming, but allowed it to occur in order to have grounds for the United States enter the Second World War on the side of the allies. These theories have been largely debunked, but they persist even today, and even to the extent that they were the subject of US government investigation as recently as 1995. Following the attack, this theory was most strongly promoted by John T. Flynn, a co-founder of the non-interventionist America First Committee. In September of 1944 he published a 46-page booklet entitled The Truth about Pearl Harbor. In it, he made the case that President Roosevelt and his inner circle had been plotting to provoke the Japanese into an attack on the U.S. and thus provide a reason to enter the war since January of 1941.
In support of this arguments, many conspiracy theorists point to a memo dated October 7, 1940, from Lieutenant Commander Arthur H. McCollum of the Office of Naval Intelligence to Navy Captains Walter S. Anderson and Dudley Knox. In the memo, McCollum sets out eight actions which might have the effect of provoking Japan into attacking the United States. The memo was classified until 1994. Conspiracy theorists, such as Gore Vidal, saw a smoking gun in this line: "If by these means Japan could be led to commit an overt act of war, so much the better." However there is no evidence that this memo or even a summary of it actually reached President Roosevelt, or any senior administration or military official for that matter.
It is generally accepted by many historians that Roosevelt wanted the U.S. to intervene in the war against Germany, though his official position was one of neutrality, since the public appetite was not one wanting war. But previous German acts of aggression against the United States had not caused a swell in public opinion favoring war. For example, on October 17, 1941, a German U-boat torpedoed a U.S. destroyer, USS Kearny, inflicting severe damage and killing eleven crewmen. Two weeks after the attack on the Kearny, a submarine sank an American destroyer, USS Reuben James, killing 115 sailors. Contemporary diplomatic communication at the time however, made it clear that if the US and Japan went to war, Germany would also declare war on the United States, in support of its ally Japan.
By late 1941, US code breakers had broken several Japanese ciphers. But Japanese traffic was too heavy for the undermanned Combat Intelligence Unit. The Japanese code known as "Purple", which was used by the Japanese Foreign Office and only for diplomatic (but not for military) messages, was broken by Army cryptographers in 1940. A 14-part message using this code, sent from Japan to its embassy in Washington, was decoded in Washington on December 6th and 7th. The message said that the Japanese intended to break off diplomatic relations with the United States, and it was to be delivered by the Japanese ambassador at 1 p.m. Washington time (dawn in the Pacific). When General George Marshall was given the intercept on the morning of December 7, he ordered a warning message sent to American bases in the area, including Hawaii. The message was not received until the attack was already underway.
As the Japanese attack force, known as the "Kido Butai," were on route to Hawaii, radio signals were said to be detected that alerted U.S. intelligence to the imminent attack. However surviving officers from the Japanese ships claimed there was no radio traffic to have been overheard by anyone. They say that their radio operators had been left in Japan to send fake traffic, and all radio transmitters aboard the ships, including those in the airplanes, were turned off in order to prevent any inadvertent or unauthorized broadcast. A report written by a US Naval officer dated December 10, 1941 and titled "Record for Posterity", does not support claims of Kido Butai broadcasting.
According to a 1942 Japanese after action report, "In order to keep strict radio silence, steps such as taking off fuses in the circuit, and holding and sealing the keys were taken. During the operation, the strict radio silence was perfectly carried out." For two weeks before the attack, the ships of Kido Butai used flag and light signals (semaphore and blinker).
Locally, Naval Intelligence in Hawaii had been tapping telephones at the Japanese Consulate before the 7th, but the Navy's tap was discovered and removed in the first week of December.
Throughout 1941, the U.S., Britain, and the Netherlands collected considerable evidence suggesting Japan was planning some new military campaign. Many in the Japanese military had disagreed with Admiral Isoroku Yamamoto's idea of attacking the U.S. Fleet at Pearl Harbor when it was first proposed in early 1941, and remained reluctant after the Navy approved planning and training for an attack beginning in spring 1941. The Japanese focus on Southeast Asia was accurately reflected in U.S. intelligence assessments. Attacks against Thailand, Malaya, French Indochina, the Dutch East Indies, the Philippines, or even Russia appeared more likely than an attack on Pearl Harbor, which was never mentioned.
The Japanese made no secret of planning by the Imperial Japanese Navy for the contingency of war with the U.S. This strategy expected the Japanese fleet to take a defensive posture, awaiting U.S. attack. Yamamoto's decision to shift the focus of the confrontation with the U.S. as far east as Pearl Harbor, and to use his aircraft carriers to cripple the American battleships, was a radical an unexpected departure from previous doctrine that analysts might have expected.
One conspiracy theory alleges that Winston Churchill had significant advance knowledge of the attack on Pearl Harbor but intentionally chose not to share this information with the Americans in order to secure their participation in the war. No cogent evidence to support this theory has been found.
In late November 1941, both the U.S. Navy and Army sent explicit warnings of war with Japan to all Pacific commands. On November 27 Washington sent a final alert to Pacific American military commanders, including a message sent to Admiral Husband E. Kimmel at Pearl Harbor, which read in part: "This dispatch is to be considered a war warning...an aggression move by Japan is expected within the next days." These messages predicted the high probability of imminent war with Japan, and instructed recipients to be on the alert for war, they did not mention the likelihood of an attack on Pearl Harbor.
Little was done to prepare for an air attack on Pearl Harbor, in part because this was not seen as a significant likelihood, and also because of inter-service rivalries between the army and navy. Hawaii remained dependent on Washington for intelligence, but this was sent to the army, who usually left the navy out of the loop.
None of the three U.S. Pacific Fleet aircraft carriers were in Pearl Harbor when the attack came. This has been alleged by some to be evidence of advance knowledge of the attack by those in charge of their disposition; the carriers were supposedly away so as to save them (the most valuable ships) from attack.
The two carriers then operating with the Pacific Fleet, Enterprise and Lexington, were on missions to deliver fighters to Wake and Midway Islands. At the time of the attack, Enterprise was about 200 miles west of Pearl Harbor. Enterprise had been scheduled to be back on December 6, but was delayed by weather.
In spite of this, Vice Admiral Ruthven E. Libby later stated, "I will go to my grave convinced that FDR ordered Pearl Harbor to let happen. He must have known." Conspiracy theorists cite the lack of any courts-martial as well as the fact that many documents pertaining to the attack remain classified to this day, and many documents were destroyed.
The U.S. government made nine official inquiries into the attack on Pearl Harbor between 1941 and 1946, and a tenth in 1995. These included an inquiry by Secretary of the Navy Frank Knox (1941); the Roberts Commission (1941–42); the Hart Inquiry (1944); the Army Pearl Harbor Board (1944); the Naval Court of Inquiry (1944); the Hewitt investigation; the Clarke investigation; the Congressional Inquiry (Pearl Harbor Committee; 1945–46); a top-secret inquiry by Secretary of War Henry L. Stimson, authorized by Congress and carried out by Henry Clausen (the Clausen Inquiry; 1946); and the Thurmond-Spence hearing, in April 1995, which produced the Dorn Report. These inquiries generally cite incompetence, underestimation, and misapprehension of Japanese capabilities and intentions. They also note problems resulting from excessive secrecy about cryptography; division of responsibility between Army and Navy (and mistrust between the two) and a lack of adequate manpower for intelligence.
While it is generally acknowledged that the attack on Pearl Harbor conveniently meshed with the desires of President Roosevelt to have the United States join the allied cause, no convincing evidence presents itself to support Admiral Libby's contention that President Roosevelt knew that the attack on Pearl Harbor was coming, but allowed it to happen as a pretext to gaining public support for US entry into the Second World War, at a cost of 2,403 American lives.
In support of this arguments, many conspiracy theorists point to a memo dated October 7, 1940, from Lieutenant Commander Arthur H. McCollum of the Office of Naval Intelligence to Navy Captains Walter S. Anderson and Dudley Knox. In the memo, McCollum sets out eight actions which might have the effect of provoking Japan into attacking the United States. The memo was classified until 1994. Conspiracy theorists, such as Gore Vidal, saw a smoking gun in this line: "If by these means Japan could be led to commit an overt act of war, so much the better." However there is no evidence that this memo or even a summary of it actually reached President Roosevelt, or any senior administration or military official for that matter.
It is generally accepted by many historians that Roosevelt wanted the U.S. to intervene in the war against Germany, though his official position was one of neutrality, since the public appetite was not one wanting war. But previous German acts of aggression against the United States had not caused a swell in public opinion favoring war. For example, on October 17, 1941, a German U-boat torpedoed a U.S. destroyer, USS Kearny, inflicting severe damage and killing eleven crewmen. Two weeks after the attack on the Kearny, a submarine sank an American destroyer, USS Reuben James, killing 115 sailors. Contemporary diplomatic communication at the time however, made it clear that if the US and Japan went to war, Germany would also declare war on the United States, in support of its ally Japan.
By late 1941, US code breakers had broken several Japanese ciphers. But Japanese traffic was too heavy for the undermanned Combat Intelligence Unit. The Japanese code known as "Purple", which was used by the Japanese Foreign Office and only for diplomatic (but not for military) messages, was broken by Army cryptographers in 1940. A 14-part message using this code, sent from Japan to its embassy in Washington, was decoded in Washington on December 6th and 7th. The message said that the Japanese intended to break off diplomatic relations with the United States, and it was to be delivered by the Japanese ambassador at 1 p.m. Washington time (dawn in the Pacific). When General George Marshall was given the intercept on the morning of December 7, he ordered a warning message sent to American bases in the area, including Hawaii. The message was not received until the attack was already underway.
As the Japanese attack force, known as the "Kido Butai," were on route to Hawaii, radio signals were said to be detected that alerted U.S. intelligence to the imminent attack. However surviving officers from the Japanese ships claimed there was no radio traffic to have been overheard by anyone. They say that their radio operators had been left in Japan to send fake traffic, and all radio transmitters aboard the ships, including those in the airplanes, were turned off in order to prevent any inadvertent or unauthorized broadcast. A report written by a US Naval officer dated December 10, 1941 and titled "Record for Posterity", does not support claims of Kido Butai broadcasting.
According to a 1942 Japanese after action report, "In order to keep strict radio silence, steps such as taking off fuses in the circuit, and holding and sealing the keys were taken. During the operation, the strict radio silence was perfectly carried out." For two weeks before the attack, the ships of Kido Butai used flag and light signals (semaphore and blinker).
Locally, Naval Intelligence in Hawaii had been tapping telephones at the Japanese Consulate before the 7th, but the Navy's tap was discovered and removed in the first week of December.
Throughout 1941, the U.S., Britain, and the Netherlands collected considerable evidence suggesting Japan was planning some new military campaign. Many in the Japanese military had disagreed with Admiral Isoroku Yamamoto's idea of attacking the U.S. Fleet at Pearl Harbor when it was first proposed in early 1941, and remained reluctant after the Navy approved planning and training for an attack beginning in spring 1941. The Japanese focus on Southeast Asia was accurately reflected in U.S. intelligence assessments. Attacks against Thailand, Malaya, French Indochina, the Dutch East Indies, the Philippines, or even Russia appeared more likely than an attack on Pearl Harbor, which was never mentioned.
The Japanese made no secret of planning by the Imperial Japanese Navy for the contingency of war with the U.S. This strategy expected the Japanese fleet to take a defensive posture, awaiting U.S. attack. Yamamoto's decision to shift the focus of the confrontation with the U.S. as far east as Pearl Harbor, and to use his aircraft carriers to cripple the American battleships, was a radical an unexpected departure from previous doctrine that analysts might have expected.
One conspiracy theory alleges that Winston Churchill had significant advance knowledge of the attack on Pearl Harbor but intentionally chose not to share this information with the Americans in order to secure their participation in the war. No cogent evidence to support this theory has been found.
In late November 1941, both the U.S. Navy and Army sent explicit warnings of war with Japan to all Pacific commands. On November 27 Washington sent a final alert to Pacific American military commanders, including a message sent to Admiral Husband E. Kimmel at Pearl Harbor, which read in part: "This dispatch is to be considered a war warning...an aggression move by Japan is expected within the next days." These messages predicted the high probability of imminent war with Japan, and instructed recipients to be on the alert for war, they did not mention the likelihood of an attack on Pearl Harbor.
Little was done to prepare for an air attack on Pearl Harbor, in part because this was not seen as a significant likelihood, and also because of inter-service rivalries between the army and navy. Hawaii remained dependent on Washington for intelligence, but this was sent to the army, who usually left the navy out of the loop.
None of the three U.S. Pacific Fleet aircraft carriers were in Pearl Harbor when the attack came. This has been alleged by some to be evidence of advance knowledge of the attack by those in charge of their disposition; the carriers were supposedly away so as to save them (the most valuable ships) from attack.
The two carriers then operating with the Pacific Fleet, Enterprise and Lexington, were on missions to deliver fighters to Wake and Midway Islands. At the time of the attack, Enterprise was about 200 miles west of Pearl Harbor. Enterprise had been scheduled to be back on December 6, but was delayed by weather.
In spite of this, Vice Admiral Ruthven E. Libby later stated, "I will go to my grave convinced that FDR ordered Pearl Harbor to let happen. He must have known." Conspiracy theorists cite the lack of any courts-martial as well as the fact that many documents pertaining to the attack remain classified to this day, and many documents were destroyed.
The U.S. government made nine official inquiries into the attack on Pearl Harbor between 1941 and 1946, and a tenth in 1995. These included an inquiry by Secretary of the Navy Frank Knox (1941); the Roberts Commission (1941–42); the Hart Inquiry (1944); the Army Pearl Harbor Board (1944); the Naval Court of Inquiry (1944); the Hewitt investigation; the Clarke investigation; the Congressional Inquiry (Pearl Harbor Committee; 1945–46); a top-secret inquiry by Secretary of War Henry L. Stimson, authorized by Congress and carried out by Henry Clausen (the Clausen Inquiry; 1946); and the Thurmond-Spence hearing, in April 1995, which produced the Dorn Report. These inquiries generally cite incompetence, underestimation, and misapprehension of Japanese capabilities and intentions. They also note problems resulting from excessive secrecy about cryptography; division of responsibility between Army and Navy (and mistrust between the two) and a lack of adequate manpower for intelligence.
While it is generally acknowledged that the attack on Pearl Harbor conveniently meshed with the desires of President Roosevelt to have the United States join the allied cause, no convincing evidence presents itself to support Admiral Libby's contention that President Roosevelt knew that the attack on Pearl Harbor was coming, but allowed it to happen as a pretext to gaining public support for US entry into the Second World War, at a cost of 2,403 American lives.