Everything Everywhere Daily: History, Science, Geography & More - Did the US Have Advanced Knowledge of the Attack on Pearl Harbor?

Episode Date: December 7, 2023

On December 7, 1941, the United States and the rest of the world were shocked by a surprise attack by the Japanese Empire on the American Navy stationed in Pearl Harbor, Hawaii.  However, in its aftermath, there have been people who have wondered and speculated that the American government knew about the attack and did nothing to prevent it as an excuse to get the United States into the war.  Learn more about whether the United States government had advanced knowledge of the Pearl Harbor attacks on this episode of Everything Everywhere Daily. Sponsors BetterHelp Visit BetterHelp.com/everywhere today to get 10% off your first month ButcherBox Sign up today at butcherbox.com/daily and use code daily to choose your free steak for a year and get $20 off."  Subscribe to the podcast!  https://link.chtbl.com/EverythingEverywhere?sid=ShowNotes -------------------------------- Executive Producer: Charles Daniel Associate Producers: Peter Bennett & Cameron Kieffer   Become a supporter on Patreon: https://www.patreon.com/everythingeverywhere Update your podcast app at newpodcastapps.com Discord Server: https://discord.gg/UkRUJFh Instagram: https://www.instagram.com/everythingeverywhere/ Facebook Group: https://www.facebook.com/groups/everythingeverywheredaily Twitter: https://twitter.com/everywheretrip Website: https://everything-everywhere.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices

On December 7, 1941, the United States and the rest of the world were shocked by a surprise attack by the Japanese Empire on the American Navy stationed in Pearl Harbor, Hawaii. However, in its aftermath, there have been people who have wondered and speculated that the United States government knew about the attack and did nothing to prevent it as an excuse to get the United States into the war. Learn more about whether the United States government had advanced knowledge of the Pearl Harbor attacks on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR.

I don't normally delve into what would be considered conspiracy theories on this show. many of them are absolutely ridiculous and aren't worth the time it would take to debunk them. The problem is, is that there have been conspiracies throughout history. The assassination of Julius Caesar was a conspiracy, as was the assassination of Abraham Lincoln. Anything that is a secret confined to a small group of people can be defined as a conspiracy. So, to be true to history, you have to acknowledge that sometimes conspiracies have been true. On the other hand, I am also a big believer in Hanlon's Razor, which, if you can remember back to my episode on eponymous laws, states, never attribute to malice that which is adequately explained by stupidity. So the big question was if the attack on Pearl Harbor was an intelligence failure, or if it was allowed to happen intentionally.

To understand why some people think that it was allowed to happen intentionally, we have to go back to the American attitude towards. the war before Pearl Harbor. Prior to the attack, public sentiment was strongly in favor of remaining neutral. Over 100,000 Americans were killed in the First World War, and after the war, many Americans questioned what it was for. Americans had died in a European war where European countries were fighting over European soil. Throughout the 1930s, isolationism and neutrality were official U.S. policy. When it appeared that war might break out in Europe again, the United States Congress passed the Neutrality Act of 1935, which banned the sale of arms, ammunition, and implements of war to any country that was in a conflict. With the outbreak of the Spanish

Civil War, the Neutrality Act was amended in 1936 and 1937 to put even more restrictions on involvement in civil wars and prevented the United States from even transporting anyone who might be a belligerent in any conflict. When Germany invaded Poland in 1939, President Franklin Roosevelt pushed for loosening the term so they could support France, Britain, and China. And this eventually resulted in the Lend-Lease Act in 1941, which provided support for those countries. However, there was still clear support in Congress for continuing neutrality and staying out of the war. In the lead up to Pearl Harbor, the Roosevelt administration was working under the assumption that the United States was going to get sucked into the war at some point.

If you remember back to my episode on the Plan Dog Memorandum, the military had put together several different war plans known as the Rainbow Plans based on several different scenarios. All of the plans were based around war with Japan, first and foremost, with the possibility of war with Germany second. So I don't think there's a lot of historical debate about the following facts. Franklin Roosevelt wanted to join the war effort against Germany and Japan, that he couldn't do so without the direct approval of, of the United States Congress, and that the United States had been planning for the eventuality of a war with Japan. So using those facts as a starting point, one of the first arguments that's made in the theory that the United States knew about Pearl Harbor before it was going to happen, is that Franklin Roosevelt provoked Japan into attacking, that the Japanese had no choice

but to lash out against the United States. To be sure, the United States had put a great deal of economic pressure on Japan in the years leading up to Pearl Harbor. The United States had placed an embargo on Japan, preventing the shipment of oil, gasoline, metals, and other strategic goods. Many other Western countries followed suit, which resulted in Japan losing 90% of its imported oil and three-quarters of its foreign trade. Without access to oil, Japan needed to find new sources of fuel for its Navy and, quite frankly, for its entire economy, which was one of the reasons it set out to invade the Dutch East Indies and Malaya where there were reserves of oil. One could make the case that the U.S. oil embargo, and remember the United States was the largest

oil producer in the world at that time, forced Japan's hand to seek new oil sources. Japan only had three years' worth of reserves left before they would be out of fuel. However, Japan's desire for oil had nothing to do with the United States per se. Japan could have easily just sidestepped the United States, attacked British and Dutch interest in Asia and not given the United States a cause for war. The Japanese made the decision to attack the United States to attempt a decapitation attack to prevent the United States from interfering with their invasion of Southeast Asia. So, for this part of the theory, I will definitely give it partial credit.

However, this isn't a smoking gun. Even if you attribute U.S. sanctions on Japan as being the reason why Japan attacked the United States, and that's not an unreasonable assumption, it doesn't mean that's not a reasonable assumption, It doesn't mean that this was the intent of the sanctions or that anybody in the Roosevelt administration wanted something like Pearl Harbor to take place. Another thing is that while the actual attack on December 7th was a surprise, war with Japan was not really a surprise for anybody. The documented statements of government officials in the weeks preceding Pearl Harbor also indicate that they thought things were going to be coming to a head soon. On November 25, 1941, the then Secretary of War, Henry Stimson, wrote in his personal diary, quote, Roosevelt brought up the event that we were likely to be attacked by the Japanese.

The question was how we should maneuver them into the position of firing the first shot without allowing too much danger to ourselves. End quote. Moreover, just two days later on November 27th, Stimston informed the United States Pacific commanders that, quote, negotiations with Japan appear to be terminated to all practical purposes. Japanese future action unpredictable, but hostile action possible at any moment. If hostilities cannot be avoided, the United States desires that Japan commit the first overt act. End quote. And there were certainly officials within the government who wanted the Japanese to attack first.

As early as October 7, 1940, Lieutenant Commander Arthur H. McCollum of the Office of Naval intelligence sent a memo to Navy captains Walter Anderson and Dudley Knox, delineating eight ways the United States could provoke a war with Japan. This document was classified until 1994, but in it was the following damning line, quote, if by these means Japan could be led to commit an overt act of war, so much the better. This idea that they felt an attack was imminent was not just a belief held in the halls of power. A poll conducted by the Gallup Organization conducted just days before the attack on Pearl Harbor,

and, oddly enough, published on December 8th, showed that 52% of the American public expected that there was going to be a war with Japan. But again, these are pretty general claims. Even if they thought war was coming, it doesn't mean that they had specific knowledge of the events of December 7th. Japanese planning for the attack began

in the spring of 1941, so it would have been impossible for anyone to have knowledge prior to that date. And also, the Emperor didn't give final approval of the plan until December 1st, just a week before the attack. So if the United States had knowledge of the Japanese attack on Pearl Harbor, they would had to have cracked the Japanese military code before the attack took place. American signal intelligence before the war was a bit of a mess, and not the organization it was to become during the war. The Japanese diplomatic code, known as purple, was cracked in 1940. However, the Japanese never sent any details of the Pearl Harbor attack via their diplomatic channels. The only hint American codebreakers had that something was up took place on December 6th, the day before the attack. A 14-part communique was sent via the Purple Code to the Japanese

embassy in Washington, D.C. The document contained orders for the Japanese ambassador to break off diplomatic relations with the United States. The first 13 pages were decrypted before news of the attack became known and were delivered to the president and other top military officials. Some who saw the document thought that it was simply Japan cutting off diplomatic ties. Roosevelt, on the other hand, saw it as the start of war. And mind you, this is only hours before Pearl Harbor actually took place. On the morning of December 7th, Army Chief of Staff General George Marshall sent a war

to all U.S. forces in the Pacific, but by the time the message reached Pearl Harbor, it was already too late. In all the years since the attack on Pearl Harbor, there hasn't been any documentation indicating that Japan's military code, known as JN25, was broken before the attack, and no one has ever come forward to say that it had been broken. The final theory is that the Americans were aware of the fleet heading towards Hawaii because of intercepted radio signals. However, there was no radio traffic because the entire fleet and all of the airplanes were under radio silence. In fact, there were no radio operators on the ships because they were all left back in Japan to send fake transmissions. In fact, radios were disabled on most of the ships just to prevent any radio transmissions that could have been intercepted.

Once the war was over, there was a lot we learned from Japanese files during the war. One of the things that was learned was that the operational secrecy around the Pearl Harbor attack was so great that even the Germans and Italians, Japan supposed allies, had no idea what was going to happen. There is a lot more research that's been done on this topic than what I can cover in an episode of this podcast. However, there is an almost universal consensus among historians that no one in the United States government or the intelligence services was aware of the plans for the attack on Pearl Harbor before it happened. That being said, it's easy to understand why some people think the United States did have knowledge of the attack. There was widespread belief in the government and in the public that a war with Japan was inevitable. There were some in the intelligence services and in the military who felt that war with Japan was desirable. The attack on the United States may have been the result of the American embargo of Japan.

In the weeks and days leading up to the attack, there were clear indications that something was going to happen imminently. However, nothing has appeared in over 80 years that would indicate that there was advanced knowledge of exactly what would happen and when it would happen. The argument that the United States knew and, in fact, did nothing to prevent the attack, was first put forward in 1944 by John T. Flynn, the co-founder of the American First Committee, the isolationist group that was against the war before Pearl Harbor. The Pearl Harbor attack was a disaster and an embarrassment for the United States government. In the days immediately after the attack, and for several years after, there were nine different investigative committees that took place into the Pearl Harbor attack and how it was allowed to happen. In 1995, a 10th investigation took place by the United States Congress. The various investigations found incompetence, problems with code breaking, failures in communication between various branches of the government, and severe underestimations of Japan's military capabilities. But what they didn't find, and what no one has come forward with since the attack happened,

was evidence that anybody knew it was going to happen before it did. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Peter Bennett and Cameron Kiever. I wanted to give a big thanks to everyone who supports the show on Patreon. Your support helps me put out a new show every day. And if you're interested in Everything Everywhere Daily merchandise, Patreon is currently the only place where it's available. And if you'd like to talk to other listeners of the show and get notified to future episodes and projects, please join my Facebook group or Discord server.

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