Author: Maya
As early as 1938, the threat from Nazi Germany was imminent. The U.S. Congress and the Army and Navy Committee instructed the Joint Planning Committee to study the strategy that Japan attacked Philippines under the formation of the German, Italian and Japanese axis, so that the U.S. Navy must face the war between the two oceans, that is, the Rainbow Series Plan. This marks the beginning of the formal formulation of the strategy toward Japan during World War II .
Under this circumstance, the United States further strengthened the collection of information on all aspects of Japan, especially the naval strength. However, the large amount of confidentiality work done by the Japanese Navy and the prevention and news review of institutions such as the special high school courses make it difficult for the US intelligence work to be carried out. The fanatical atmosphere of anti-espionage and anti-espionage under the militarist system makes it difficult for the US to obtain information from shipyard workers and other civilian channels. In addition, the bureaucracy within the US military has also made it impossible for many correct intelligence information to be adopted in a timely manner and quickly appeared in relevant documents.
report cover
Even in the documents issued by the US Navy after the war started on December 29, 1941, there were many incorrect estimates of the performance and number of of the Japanese Navy's warship.
first is battleship , which is also the first part mentioned in the document. After all, in 1941, aircraft carrier did not yet reflect its overwhelming advantage over battleships. No country could completely suppress the bet on the aircraft carrier that could only be called a budding aircraft carrier at that time. It must be very cautious in the construction of the main ship that is expensive and concerns national security. The US believes that it is natural for Japan to build a new type of battleship, but Japan's confidentiality work on the construction of the Yamato-class is very good, so the US's judgment on the parameters of Japan's new battleship is completely wrong.
, which was sailing at high speed in 1941, , Yamato battleship
In the US manual, the new type of battleship being built by Japan is called Hi-level (actually this is the name of the seaplane mothership). In terms of construction quantity, two have been completed, and even the No. 2 has been named Takamatsu (this does not conform to Japan's tradition of naming battleships after the country of Lingjian. Takamatsu is the Guardian of the Japanese royal family), and another one has been completed but has not been in service, and two are about to be completed.
In terms of performance data, the US only generally believes that the ship's displacement is more than 40,000 tons, the maximum speed reaches 30 knots, and the main gun is 9 406mm guns. In addition, the document also indicates that there is no reliable source of these data, that is, the intelligence source is not reliable or that these data are just speculations made by the US based on some other information.
Two views of Yamato
It is obvious that in terms of construction quantity and performance parameters, the ship is far from the actual Yamato class built, and its speed is also much different from the more detailed design of the King Kong Agent (the speed of the King Kong Agent is only 26 knots). The design that is closer to it is only the design of the 40,000-ton high-speed battleship plan that continues from the King Kong Agent. However, the plan did not have a detailed design and the design was in the treaty era. It was more of an argument, so it was unlikely to be acquired by the US side.
In addition to the so-called Japanese upgrade, the US also believes that Japan has built four pocket battleships with displacement of 12,000-15,000 tons, three of which have been completed. Other parameters of this class of ships are unknown, the speed is said to be 30 knots, and it is equipped with 6 305mm cannons . The US also pointed out that this class of ships was influenced by the German German class, so they can be considered as a kind of heavy cruiser for strengthening protection (however, the German class was not designed according to this idea, which shows that the US also had a great deviation in its understanding of the German class at that time).
In terms of the parameters of other Japanese battleships, since they are all products before the agreement of the Treaty of Washington, both performance parameters and quantity are relatively open.What’s amazing is that for some reason, the US believes that these battleships had not removed the underwater torpedo tube until 1941 - backward equipment with huge hidden dangers that had been eliminated by various countries. In addition, the US side also mistakenly judged that the King Kong was downgraded to a training ship like the Biru and that the two ships did not return to the state of a high-speed battleship, and the speed of the King Kong class was 4 knots lower than the actual situation.
One of the solutions of the King Kong ship, 9 main guns, and 40,000 tons high-speed case developed on this basis.
In the judgment of the aircraft carrier , the US mistakenly judged Xianghe and Ruihe as two different models, and seriously underestimated the displacement and number of aircraft carriers of the two ships. Among them, Xianghe is considered to be the front type of Ruihe, with a displacement of 15,000 tons, while Ruihe has expanded the displacement to 20,000 tons (in fact, the public test displacement of the two ships reached 29,800 tons, and the standard displacement was 25,675 tons). The maximum speed of both ships is 30 knots (actually 34.2 knots). In terms of the number of carrier-based aircraft, the US believes that Xianghe's carrying capacity is 30-40 aircraft, while Ruihe has increased to 45 aircraft (the actual number of carrier-based aircraft of the two ships is 72 commonly used aircraft + 12 reusable aircraft).
In addition, the number of its dual-mounted 127mm anti-aircraft guns is also two less than the actual ones. This shows that the strength of these two types of aircraft carriers is greatly underestimated in the US military's report. However, in terms of construction quantity, the US military believes that only one Shohe class has been built as a transitional model, while three of the so-called Ruihe class have been built. The second ship has even been named the Takasago and all three have been completed.
. For Canglong and Feilong, its displacement is also underestimated to 10,500 tons (actual standard displacement is 15,900 tons), and its size is also underestimated: the total length is 209.5 meters, the width is 20.72 meters, the draft is 5.02 meters (actually 227.5 meters, 22.32 meters, 7.74 meters), and the speed is also considered to be only 30 knots (actually 34.5 knots). However, the estimate of its carrying capacity is not much different from the actual situation: 53 aircraft (actually 57 commonly used aircraft + 16 spare aircraft). I don’t know why the US side believes that the capacity of Xianghe and Ruihe, which are much larger and are not modified ships, will be much lower than that of these two ships. The displacement of the two original cases of
Canglong is in line with the US military's prediction, with only 10,500 tons. Obviously, this displacement cannot meet the performance requirements at all. In addition, it is even more unrealistic and impractical to carry a 203mm main gun, so these two solutions were quickly abandoned.
In terms of construction quantity, the US also built an additional Gulong ship out of thin air. The problem of underestimating displacement also occurs in the two ships of Akagi and Kaga . The US believes that its displacement is only 26,900 tons (actually 36,500 tons), Kaga's maximum speed is 24 knots (actually 28.3 knots), Akagi's 28.5 knots (actually 31.2 knots), and the carrier capacity of both ships is 30-40 (actually 66 commonly used aircraft + 25 spare aircraft, Kaga has reached the level of 72 commonly used aircraft + 18 spare aircraft), and the size of the two ships has also shrunk in the eyes of the US.
Since these large aircraft carriers were filed in the file, Longxiang, as the light aircraft carrier, is naturally unavoidable: the displacement has been cut from 12,732 tons to 7,600 tons, the carrying capacity has also been cut from 36 + 12 to 24, and its speed has also been cut from 4 knots and only 25 knots left. The Big Eagle, which was completed in 1941, was modified by the merchant ship Kasugamaru, but did not appear in the US intelligence.
In the evaluation of cruiser , the US side did not make any mistakes out of nothing, and its intelligence accuracy was relatively higher, but the deviation also existed: the displacement of all Japanese cruisers was underestimated, and most of the speed was underestimated by 1-2 knots, but the above was not as outrageous as the aircraft carrier part. In addition, the caliber of all torpedo launchers is considered to be 533 mm in large quantities used by countries rather than the actual 610 mm.
Ligan-class
Specifically, the Ligan-class main gun was judged to be the configuration in the initial design of four triple-mounted 155mm three-year artillery. In addition, the No. 3 turret was mistakenly lifted to the same height as the No. 2 turret, and the capacity of the seaplane is also considered to be only four (actually 6). The judgment of the highest-level US military is basically accurate.
The actual Ligan-level
. For Kaohsiung and Miao-level, the US military judged that its four-unit torpedo launch tubes was only two, and half of them were cut off. Their anti-aircraft firepower showed eight 47mm anti-aircraft guns that the Japanese had never equipped before, and the large-caliber anti-aircraft guns were also considered to be old 120mm anti-aircraft guns. However, the number of seaplanes of the two types of ships is considered to be four as the Ligan class with special aviation decks, which is twice as high as the actual one. When it comes to the two-level ships of Guying and Qingye, the torpedo launch tubes are not considered to have been replaced with two quad-mounted launch tubes, but are still 12 old single-mounted launch tubes.
Ancient Eagle, the old torpedo tubes of Qingye, the US military intelligence believes that the old type
For the destroyer , the US side did not have any major deviation in its judgment on speed and armed forces. The main problem is the caliber of the torpedo tube mentioned above and the significantly underestimated displacement throughout the text. In addition, it is the judgment of the type brought by similar appearance and the misjudgment of the quantity brought by huge quantity. The main error is that Yangyan class is considered to be the same-class ship of Chaochao class, with a total of 21 ships (actually 18 ships in service with Yangyan class and 10 Chaochao class). Moreover, its displacement was cut by 500 tons and only 1,500 tons remained, which was less than the old-fashioned snow blowing level 1,700 tons (another incredible judgment).
Overall, the US military's judgment of the strength of the Japanese Navy after the Pearl Harbor incident was huge. There were a lot of errors in the judgment of the specific performance of the equipment and the number of warships serving, and the larger the ship, the worse the US's judgment accuracy. Overall, the United States generally underestimates the specific performance of the equipment and overestimates the construction quantity. There are even many models that do not exist at all, and the judgment of many performance parameters does not conform to basic logic.
s attack on Pearl Harbor
On the one hand, this is due to Japan's confidentiality measures, and on the other hand, the more chaotic sources of intelligence and the bureaucracy of the United States are also to blame. A typical example is the judgment of the caliber of the Yamato main gun: in 1944 there was already a lot of intelligence that showed that the caliber of the Yamato main gun was not 16 inches but 18 inches. After the actual battle between and Lyte Bay , the US front-line troops basically agreed with this view, but the bureaucratic system ignored a large amount of facts and used some plausible intelligence and reasons to insist on its own judgment as 16 inches.
It was not until May 1945 that the U.S. military's bureaucratic system finally officially changed the caliber of Yamato's main gun to 18 inches in the issued document. However, at this time, both Yamato classes had been buried at the bottom of the sea, and this correction had lost its meaning.
The performance of relevant documents of the US Navy also shows the difficulty in judging the parameters of active equipment in other countries: even the military that has a large number of intelligence resources and related talents has made a large number of judgments that seem outrageous in the future, so we don’t have to be too serious about some seemingly well-known parameter analysis on the Internet.
