In 1932 Admiral Harry E. Yarnell launched a simulated carrier attack on Pearl Harbour, in almost exactly the same way as the actual Japanese attack 10 years later. Declared a total success by umpires, Yarnell warned of the vulnerability. Naval Intelligence knew Japanese writers reported on it.

Harry E. Yarnell

Admiral Harry Ervin Yarnell (18 October 1875 – 7 July 1959) was an American naval officer whose career spanned over 51 years and three wars, from the Spanish–American War through World War II.

Among his achievements was proving, in 1932 war games, that Pearl Harbor was vulnerable to a naval aerial attack. His findings were dismissed by his superiors until the Imperial Japanese Navy’s Pearl Harbor attack went just as Yarnell had predicted.

Early life and Naval career

Born near Independence, Iowa, he entered the U.S. Naval Academy in 1893. After serving on USS Oregon (BB-3) during the Battle of Santiago de Cuba, 3 July 1898, Yarnell was commissioned ensign 1 July 1899 and reported to the Asiatic Station. He served in the Philippin… Continue Reading (4 minute read)

15 thoughts on “In 1932 Admiral Harry E. Yarnell launched a simulated carrier attack on Pearl Harbour, in almost exactly the same way as the actual Japanese attack 10 years later. Declared a total success by umpires, Yarnell warned of the vulnerability. Naval Intelligence knew Japanese writers reported on it.”

  1. twofeetcia

    Additionally, it was predicted by “Father of the Air Force” Billy Mitchell a decade before that.

    In 1924, following an inspection tour of the Pacific and Far East, Brigadier General William “Billy” Mitchell offered the following warning concerning any future war with or attack by Japan on America:
    >”Attack will be launched as follows: Bombardment, attack to be made on Ford Island (Pearl Harbor) at 7:30 a.m with bombing to take place on a Sunday”

    The real bombings started at 7:55am Sunday morning December 7.

  2. Intow1

    Another fun fact about that is ,that the simulated attack did not target the repair, ammo, and fuel depots. They did not want to risk injury or damage to those sites from the target bombs that they dropped. The simulation was so closely followed by the Japanese that they too did not attack those sites,which greatly aided the Americans in repairing and re-arming so quickly after the the attack.

  3. I_Shot_The_Deathstar

    This is why I’m not a military tactician, I would have read that report and said
    “I’m sure they have reinforced it now, so there’s no way we can attack Pearl Harbor.” Yeah I would have been a bad General.

  4. yogfthagen


    US did not think Japan could do underway ship replenishment, so Pearl Harbor was too far away for a Japanese strike.

    Pearl Harbor was too shallow for aerial torpedoes. In fact, Japan had to modify their torpedoes to work.

    US expected an attack on the Philippines, which actually happened. The US thought that would take up the IJN resources. The US did not expect the attacks on Singapore, Dutch East Indies, or the islands that were ALSO hit the same day.

    US military in Hawaii was expecting sabotage attacks. The way you defend against those is to keep everything as close as possible, so you only have to guard as small an area as possible.

    US military put out a War Warning based on the breakdown of trade negotiations.

    US believed that Japan was not racially capable of pulling off such a complicated attack. Literally. Racism led the US and the Brits to underestimate Japanese capabilities.

    US Navy believed that battleships were still the primary capital ship. They would not sacrifice what they believed to be their BEST WEAPONS in the first hours of the war, because….?

    Is it so hard to believe the US got caught with its pants down?

  5. Joss_Card

    It’s funny because Japan’s view of engaging with the Americans was terribly divided. Half of the generals thought they could win against the US, with a few that thought that the only way the US would take them seriously in talks if they gave them a show of force. “If you step aside for an American, they won’t respect you. In fact, they’ll look down on you for being so weak that you moved out of the way. If you want them to respect you, you have to bloody their nose.”

    The people trying to make a treaty with the US were only warned about the impending attack a few hours before. That was because the attack was only supposed to happen if talks broke down with the US (which they were, but the Japanese military leaders didn’t know that yet).

  6. youvepissedmeoff

    Loose lips sink ships.

  7. Luke90210

    13 months before Pearl Harbor, the British almost destroyed the Italian Navy at the Battle of Taranto. Using under 40 carrier-based planes, some of which were old biplanes, they had a smashing victory and lost only 2 planes. Theory is fine, but the Japanese military attaches in Italy (Japan and Italy were allies) passed practical info regarding a very real tactic changing naval warfare forever.

    Pearl Harbor was the samish plan, but using hundreds of the most modern planes, 6 new carriers and the most experienced naval pilots in the world.

  8. farnzz

    Moreover, the attack wasn’t a surprise. Or shouldn’t have been a surprise.

  9. Regis_Filius

    Could it have been an inspiration for TV series ‘The Designated Survivor’ plot point where >!terrorists used a simulated attack on Capital made by DOD to launch a real attack?!<

    Edit: added a spoiler tag just in case.

  10. HaroldGodwin

    I recently found out that on the morning of the attack, the radar station at Pearl Harbor picked up a huge blip on their screen that was the incoming Japanese planes and passed it up to HQ, but no one acted on it. I don’t recall if anyone was ever punished for that.

    Just think about the lives that could have been saved. Ships could have been moved so they weren’t sitting ducks, aircraft could have been scrambled to engage the incoming enemy and disrupt their formations and timing, the hospital could have been prepared, etc.

    The whole affair was negligent.

  11. ServerFirewatch2016

    Combined with the fact the Japanese had launched a similar attack by torpedo boat against Port Arthur, Korea, Japan was the most qualified to commit to the attack; while its still unlikely that Japan would have won the war, had American carriers been at port, the war would have easily dragged on another year.

  12. New_Wrangler3335

    It’s a trap for the Japanese

  13. BipedalPussyExtract

    I just love that Pearl Harbor has been the most blatantly dangled and willfully allowed to happen attack on the US in history yet people are still more afraid of being called anti patriotic than calling it out 80 years later.

  14. UnwashedApple

    They knew! They let it happen. Just like 9/11!

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