I've been reading the Wikipedia pages about the Pacific theatre in WW2; in the page describing the battle of the Coral Sea there is the following passage:

[...] the scout [from Shōkaku] confirmed that it had located "one carrier, one cruiser, and three destroyers". Another Shōkaku scout aircraft quickly confirmed the sighting. The Shōkaku aircraft actually sighted and misidentified the oiler Neosho and destroyer Sims.

During a battle, mis-identifying a ship is understandable; at Leyte Gulf even Admiral Kurita thought that the ships attacking him were major fleet units instead of mere destroyers.

The thing I don't understand in this case is, how could the pilots see five ships instead of two? How could two independent reports contain exactly the same mistakes? The pilots weren't even under attack, so they had plenty of time to make sure they were getting their facts straight.

If this question is too broad or vague, I'll accept answers detailing the procedures used by Japanese scouts for spotting, identifying, reporting and confirming other people's reports: for instance, was the information transmitted at once by voice radio, unencrypted, on an open channel?

That would explain how the second scout made the same mistake (he could have said "I confirm that" without even spotting any ship).

This is maybe a minor episode, but it altered history in a significant way, so I'd like to understand better what happened.

EDIT: I dug out some more info (even the footnotes on the Wikipedia articles are engrossing); at least some Japanese search planes in the Coral Sea battle had a pilot, an observer and a radioman.

It seems that the information was transmitted in the clear, in fact during the second day of the battle, American ships knew that they had been sighted when they intercepted messages from a Japanese scout plane.

This might explain the identical mistakes from the two scouts - the radioman and observer on the second plane were probably aware of the message from the first one, and even if rank didn't come into play, suggestion probably did.

Finally, another piece of the puzzle might come from a similar mis-identification made during the same battle by an American pilot, John Nielsen: the book Pearl Harbor to Midway explains that "the SBD's coding system was a board with pegs and holes to allow for rapid transmission of coded ship types. In Nielsen's case, the board was apparently not aligned properly". I don't know if Japanese planes had a similar system, but this might explain at least some of the mis-identification problems that plagued the Pacific theatre.

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    This is one of those things that I think may seem weird to folks new to WWII history, but you see it everywhere if you read details from actions in the Pacific Theater. So I'm inclined to say this is a good question we could use good answers for.
    – T.E.D.
    Commented Jun 22, 2020 at 14:17
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    @sempaiscuba i.e. "The Fog of War"....
    – Spencer
    Commented Jun 22, 2020 at 14:35
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    @Spencer Well, perhaps not exactly in the sense that von Clausewitz meant it, but yes. ;) Commented Jun 22, 2020 at 14:38
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    It's possible that the first scout was the senior officer and the second didn't dare to naysay his superior's observation.
    – Steve Bird
    Commented Jun 22, 2020 at 14:41
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    When you say that poor visibility doesn't explain the facts you seem to be missing the fact that visual recognition requires a great deal of training and is subject to human error. See my comment under Mark's answer for details. I was trained in, and trained other people in, visual ship recognition in the 80's while I was in the Navy Commented Jun 23, 2020 at 15:21

3 Answers 3


Mistaking the Sims for a cruiser is easy: a Sims-class destroyer has the same number of turrets (3) as the majority of American cruisers, while most American destroyers of the time had two, four, or five turrets. Without anything to provide a sense of scale, it's easy to mistake one for the other, particularly if you're not getting close enough to count the guns in each turret.

Mistaking the Neosho for a carrier is harder, but still understandable: the Cimarron-class fleet oilers have a large structure in the middle of a mostly-flat deck, a layout that at a glance is similar to the island and flight deck of a carrier.

If you're out looking for the enemy fleet, you're expecting to find carriers sailing in the company of cruisers. In psychology, this is called priming, and as long as the ships you're seeing aren't too different from the ones you expect to see, it's nearly certain that you'll misidentify them.

Spotting three destroyers that don't exist is harder to explain, but again, priming plays a role. A cruiser and carrier will not be operating alone, so when you're looking for the rest of their escorts, there's a decent chance that you'll misidentify a dark patch of ocean, the interference pattern between the two ships' wakes, or other things as poorly-seen destroyers.

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    @Davidw, everything I've found says three turrets and one unturreted deck gun. The Sims-class had stability problems, and a fourth turret would have made things worse.
    – Mark
    Commented Jun 23, 2020 at 0:23
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    I think your priming link points to the wrong URL?
    – Polygnome
    Commented Jun 23, 2020 at 8:19
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    There's a 1 instead of a 3 in the markup for the "priming" link. Commented Jun 23, 2020 at 8:53
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    Excellent answer! Michael Shermer's TED talk ( youtube.com/watch?v=8T_jwq9ph8k&t=323 ) had some examples of this phenomenon. You can also try and test it by yourself (e.g. listen to the song in reverse, and try to guess its meaning). Also, the tanker's wiki page states: "Four of the Cimarrons were converted to escort carriers in 1942", so it's a mistake easy to explain. Another one: if those scouts believed they've spotted a carrier, they probably didn't want to go closer to take a better look, as a carrier's fighters could easily shoot them down.
    – Nyos
    Commented Jun 23, 2020 at 10:26
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    I think this answer would greatly benefit from pictures comparing Sims with cruisers as well as Neosho with carriers.
    – Narusan
    Commented Jun 24, 2020 at 11:48

Misidentifying of ships from scout planes was a consistent problem for both sides in the Pacific Theater. In fact, it seems that getting a scouting report exactly right was more the exception rather than the rule. In particular, pilots appeared to have a distinct tendency to inflate the importance (or size) of the ships they were sighting.

According to Shattered Sword, here's a small list of misidentifications that happened during the battle of Midway:

  • The Destroyer Tanikaze was repeatedly identified as a light cruiser.
  • The Cruisers of Japan's CruDiv 7 were identified as battleships.
  • The next day two of those same two cruisers along with 3 destroyers escorting them (DesDiv 8) were identified as one battleship, one cruiser, and three destroyers. This report was then mistakenly upgraded to "one carrier and five destroyers", before being "corrected" back when the transmitting pilots landed.
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    If a battleship and a cruiser are close to each other, it is fairly easy to see the size difference. A few ships on the big blue sea though, and determining their size is tough from several miles up and several miles away.
    – Jon Custer
    Commented Jun 22, 2020 at 17:24
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    @JonCuster - The two cruisers in question, Mikuma and Mogami, displaced about 8,500 tons (officially. A couple K more when fully loaded). The smallest Japanese battleships displaced around 36,000. Quite correct that this is a mistake that it would be much easier to make without one of both ship types physically available to compare. So yeah, there are obviously reasons why it happened a lot. This answer is just pointing out that, for whatever reason, these kinds of mistakes were commonplace (and usually erred on the side of reporting a more important ship than it actually was).
    – T.E.D.
    Commented Jun 22, 2020 at 18:14
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    no intent to cast aspersions on the answer - I agree it was quite common - just trying to point out to readers that it was all a lot harder than some seem to think.
    – Jon Custer
    Commented Jun 22, 2020 at 19:16
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    @Joshua - perhaps less than you think - an oiler has a pretty similar shape, with a mostly high, flat top and some control structure that could well look like an island from a variety of view points (particularly if you are mostly looking down from an airplane rather than horizontally from another ship).
    – Jon Custer
    Commented Jun 22, 2020 at 22:18
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    Nobody has mentioned that flying warplanes back then was uncomfortable. Even with a helmet on, the noise level wears you out. When taxiing on the ground you are baked, at altitude you can be freezing. Unlike the warbirds in museums, the canopy may be scratched, yellowing, splattered with oil & bugs. The pilots will be constantly thinking about how much fuel they have left, especially being over water. Out over the ocean the pilots will know that even if they survive ditching, they may never be found. Sun may be in their eyes. IOW many distractions.
    – Flynn
    Commented Jun 23, 2020 at 19:01

I'd like to provide an alternative explanation that addresses the question of, "How could two independent reports contain exactly the same mistakes?", which isn't specific to this battle, but would apply here: The consequences of strict hierarchical rigidity in Japanese culture and an emphasis on conformity. This is an alternative (but not mutually exclusive) explanation to discussing the ways in which particular ships might be misidentified, as @Mark covered, or the pointing out the notion that it's in general the exception to get a scouting report exactly right as @T.E.D. mentioned.

One nice summary of analysts and historians trying to understand Japan's overall naval defeat is here, and one of the explanations is:

Japan was defeated because of strategic, logistical, and technical deficiencies over which it had very little control, because of the negative results of fallible human decision making, and because of the bureaucratic inertia found in many modern military organizations [emphasis mine]

I've been searching for sources which I've read before (but now can't find) that describe how Japanese commanders were reluctant to relay bad news and failed objectives to superiors, which hampered them learning from mistakes that were made during battle. It's not hard to imagine that the same forces were at work during the battle in question here. The battle of Coral Sea example specifically would be especially easy to rationalize along these lines if the first scout was older or higher ranking than the second scout. I'd welcome any additional sources.

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