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http://www.navweaps.com/index_tech/tech-084.htm
What did the USN know about Yamato and when?"
by Joseph Czarnecki
Updated 21 August 2002
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Oft-repeated questions about the famous Japanese Yamato class battleships include: “What did the U.S. know about these ships and when did they know it?”
According to some distinguished authors, nothing concrete was known about their characteristics until after the Occupation of Japan and the subsequent capture of their construction records. That this is not the case can be shown by a review of the available information in a few authoritative texts. The following essay is a presentation in chronological order of the status of the USN’s on-going intelligence on these battleships as gleaned from those works.
As revealed in John Prados’s “Combined Fleet Decoded,” the U.S. had made the following assessment prior to the start of the Pacific War:
In 1936, Captain Fred F. Rogers, a Japanese-language officer (which denotes an American naval intelligence officer who could speak and write Japanese, having been so taught in Japan) and the U.S. naval attaché in Tokyo, reported that “Japan had designs for warships of 45,000 to 55,000 tons,” that she “would not hesitate to build ships of at least 35,000 tons” and “would not revert to the Washington restriction on tonnage or its limit for guns.” Rogers quoted secret Diet testimony from Navy Minister Admiral Nagano Osumi to the effect that:
“...as a result of the coming no-treaty period we shall enjoy freedom of action in construction of warships in respect to category, quality and characteristics. With this freedom we may construct those ships particularly adapted for our national requirements, thereby gaining an advantage which obviates the necessity for numerical equality.”
Captain Rogers’ successor, Captain Harold M. Bemis, reported in January 1938 that “Japan has under construction two 16-inch battleships of considerably greater tonnage than 35,000 tons and is planning to lay down a third and possibly a fourth.”
Bemis’s fellow members of the international “Attachés’ Club” apparently agreed that the new ships would exceed Treaty limits. The British, German and French attachés all felt these would displace 45,000 tons. The Italian attaché was more specific at 46,000 tons with a possible tonnage increase to 50,000 tons. The Soviet attaché thought the ships would barely exceed 35,000 tons.
There was apparently some agreement among the attachés that the armament would be twelve 16-inch (41 cm) guns despite the interest shown in 18-inch guns for the No. 13 class in the 8:8 Program. The Soviet attaché had erroneously concluded that the Japanese could not lathe such large weapons without importing the necessary equipment, but rightly pegged the location of the development facility. The Italian attaché thought testing of such a weapon had failed with a burst powder chamber.
Following the start of the Pacific War, a document captured on Tulagi in August 1942 apparently provided the U.S. with their first crude schematic of the design, and for the first time confirmed a barrel-count of nine guns.
In October 1942, ONI (Office of Naval Intelligence) estimated the ships at 35,000 tons and armed with nine 16-inch guns.
In February 1943, the of interrogation of a survivor of the submarine I-1 sunk off Guadalcanal, Kuboaki Takeo, confirmed the nine-barrel count.
By the spring of 1943, CINCPAC (Commander In Chief Pacific) Intelligence listed the ships as being armed with nine 17.7-inch (45 cm) guns (the source of this information is not discussed by Prados).
In July 1943, interrogation of a captured Japanese aviator betrayed the conversion of the third ship in this class, Shinano, to a carrier and that her intended size was 50,000 tons. ONI did not believe the ship would be so large and hedged its estimate by speculating the Shinano might displace 30,000 tons after being stripped down from a battleship to a carrier.
An October 1943 message intercept referred to “special type 40 cm” ammunition and contributed to the USN thinking that these ships carried 16-inch guns. This was as intended by the Japanese, who from the inception of the super-battleship program had always referred to the 46 cm (18.1-inch) guns on the Yamato class as the “special type 40 cm” as a disinformation ploy.
On 4 February 1944, two B-24 reconnaissance aircraft overflew Truk, taking photographs. These were processed by 25 February 1944 and one of them showed a Yamato class ship visible in one corner. ONI photo interpreters at the Photographic Reconnaissance Interpretation Section Intelligence Center (PRISIC) at Pearl Harbor correctly estimated that this ship was armed with 18-inch guns. Ship-design experts called in to consult estimated the ship at a minimum of 60,000 tons and noted that this huge size was necessary in order to mount nine 18-inch guns. However, these experts then proceeded to thoroughly play Devil’s Advocate against their own position, claiming such a design was “impractical.”
In June 1944, the U.S. captured Admiral Yamamoto’s former yeoman, Noda Mitsuharu, who had now been serving with Admiral Nagumo on Saipan. Edwin Layton of CINCPAC Intelligence interrogated him and the prisoner revealed the “special type 40 cm” deception by recounting current jokes about the designation in the IJN. At this point, Layton abandoned his previous conviction that the Yamato class carried 16-inch guns and so informed a Seventh Fleet intelligence officer passing through Pearl Harbor on his way to the Southwest Pacific.
The intelligence available in February 1944 and June 1944 is discussed in a footnote on pages 534 and 535 of “Combined Fleet Decoded” which states:
“On February 25 the Truk photos were processed at PRISIC in Pearl Harbor: one picture showed the huge ship, obscured at the corner. The Office of Naval Intelligence brought ship-design experts into the discussion, concluding that the Yamato class must displace at least 60,000 tons. That also was the size experts thought necessary to mount 18-inch guns, but the same people argued that problems of stowage and propulsion, plus complications with docking and navigation, would render such a warship impractical. A Seventh Fleet intelligence officer was given this word just before returning to SOWESTPAC, then passed through Pearl Harbor, where he talked to Eddie Layton. Previously a staunch defender of the proposition the Yamatos had only 16-inch weapons, Layton was by this time interrogating prisoner Noda Mitsuharu, former yeoman to Admiral Yamamoto. Noda repeated many jokes current in the Imperial Navy about the ‘special type’ 16-inch guns of the Yamato, converting Layton. Still the ONI Weekly on August 30 carried a feature on Japanese naval guns discounting the possibility of the larger size for Yamato, and still listing her at 40,000 tons. The first reasonable [sic] accurate artist’s conception of the appearance of the Yamato appeared in the ONI Weekly on September 20 based directly on the Truk photo.”
[Re: “sic” should read “reasonably.”]
This information is apparently alluded to in Morison’s Volume XII with a footnote on page 162, stating:
“Although Yamato had participated in the Battle of Midway, these battleships were ‘mystery ships’ to the world at large; but the CINCPOA and Seventh Fleet Intelligence officers, by piecing together scraps of information, had a good idea of their size early in 1944, which was confirmed by a talkative officer prisoner in September.”
In Dulin & Garzke’s “Battleships: Axis and Neutral Battleships in World War II” we find two drawings of the class attributed to the USN during the course of the Pacific War. The first is a crude and inaccurate drawing correct only in the ship’s gross features and attributed to “summer 1944.” The second is much more accurate and given as dating from “March 1945.”
This book includes several war-time photographs of Yamato and her sister-ship Musashi, mostly taken while they were engaged during the Battle of the Sibuyan Sea on 23 October 1944. Dulin & Garzke contains two very clear images of Yamato from this battle, a less distinct photo of Musashi amidst bomb and torpedo splashes and an unidentified overhead photo of one of the ships evading attack*. The clarity of some of these photographs, as opposed to the earlier, indistinct ones, would have obviously aided intelligence officers in assessing the size and armament of these ships.
Yamato was also photographed under attack in the Inland Sea on 19 March 1945. One frame taken during this attack appears in Dulin & Garzke. Further photographs were taken during Yamato’s final engagement on 7 April 1945, including four that appear in Dulin & Garzke.
The intelligence assessment for these ships as of the time of Yamato’s “Final Sortie” may be judged by the following paragraph taken from Morison’s “History of U.S. Naval Operations in World War II,” Volume XIV:
“An eagerly anxious evening followed for TF 54. Staff officers familiar with range tables took care to remind others that Yamato’s 18.1-inch guns should have a maximum range of 45,000 yards, as against 42,000 for the 16-inch gunned battleships in Deyo’s force and 37,000 for [the 14-inch gunned] Tennessee; and that her speed should enable her to make an ‘end run’ and thrust at the transports.”
This statement effectively shows that at some point between the October 1944 battles around Leyte Gulf and Yamato’s final sortie in April 1945, the USN had come to a more complete and accurate appreciation of the Yamato’s true size and armament and was actively using that assessment for battle planning.
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Sources:
John Prados, “Combined Fleet Decoded: The Secret History of American Intelligence and the Japanese Navy in World War II”
Samuel E. Morison, “The History of United States Naval Operations in World War II,” Volumes XII and XIV
Robert O. Dulin, Jr. and William H. Garzke, Jr., “Battleships: Axis and Neutral Battleships in World War II”
"Any relations in a social order will endure if there is infused into them some of that spirit of human sympathy, which qualifies life for immortality." ~ George William Russell
This was very interresting information.
Over the weekend I hope to post one books findings about Yamato and the security that surrounded her. I have several books that all contain diffent opinions about her build and security and when we found out the correct information.
The biggest question is not "What did the inteeligence committee know", but was it passed to the people in the fleet, namly ADMS Lee, Deyo and the skippers of the BB's. I have no indication of that.
"Any relations in a social order will endure if there is infused into them some of that spirit of human sympathy, which qualifies life for immortality." ~ George William Russell
THAT is the article I was thinking about
TH,
I have a new video that suggests a new light on who would have faced the Yamato battleship wise and the story tells it would have happened at Midway. According to the newer video Yamato and her group were to attack the forces landing at Midway. The USN battleships New Jersey and her sister Iowa were just over 130 nautical miles from Midway. When it was decided that they could not reach the area even at top speed in time to stop the Japanese attack on the Midway landings by the Yamato thats when the decision was made to attack the Japanese Aircraft carriers using our airpower as to shift the Japanes attention from our landing forces which Yamato could attack to the IJN carriers which Yamato could do nothing about except watch our planes destroy them. The story tells that once the second carrier went down Yamamoto immediatly turn tail with the Yamato and cancelled the operation although they lost more then two carriers. So their view is that Iowa and New Jersey would have faced Yamato for the very first time at Midway and not the Leyte operations or "Operation Ten Go"as many others have told. The decision was made because Iowa and New Jersey could not get there in time. Not because they wanted to use airpower on them to begin with. This is only another telling of the Battle of Midway not necessarily THE truth but another version as many surround those campaigns.
Also they review Halsey's decisions at Guadal Canal and Leyte as well.
The video is from the history channel and is certainly well worth the $24.00 some of the footage from the video is absolutely priceless as far as battle line footage and footage of some ships that rarely if ever saw the spotlight in news reports from all sides Axis and Allies. Of all the dvd's I have on the battleships this one stands out among all others past and present.
They also give a different view of Hood's battle with Bizmark.
Last edited by Dreadnought; 07 Feb 06, at 14:30.
Whats the view.Originally Posted by Dreadnought
"Any relations in a social order will endure if there is infused into them some of that spirit of human sympathy, which qualifies life for immortality." ~ George William Russell
Well Spart,
The other stories I have read and watched on video claims that Hood's initial mistake was a port turn to left to become parallel with Bizmark and Prince Eugan this is supposedly when she was struck by Bizmark's salvo's as soon as she straightened up to be parallel with Bizmark. The newer video suggests that Hood was already lined up parallel with the Bizmark and Prince Eugan and had already expended three salvos at Price Eugan mistaking her for Bizmark. While they were opening fire on Prince Eugan the Bizmarks FCR had pinpointed Hood's exact position and she let loose on Hood sinking her. The mistake they claim was not hitting Bizmark first as Prince Eugan was not as accurate as Bizmarks state of the art optical range finders. And Prince Eugan's guns were 8x8 no match for Hood but Bizmark shared the same size guns as Hood's (8X15) making all the difference in the world once given time to point them at Hood. These experts claim those first three salvo's had they been spent on Bizmark would have made all the difference in the world to that battle. Instead we already know the outcome.
Like I have stated above not THE truth just another view of it.
Very interesting Dread! Good to see that they don't suscribe to the "Prinz Eugen sunk Hood " theory! I have never believed it.As for the main guns, now the British 15"/42 Naval Rifle was probably the most successful one of all time. In its modernized version it was a match for and I feel superior to any other Axis gun (except the Yamato's 18"/45). Look at the performances of HMS Warspite and others! Bit the Hood was carrying an unmodernized version of the rifle, one that was actually outranged by the 11"/50 of the Scharnhosts. What really doomed Hood I believe is having to do battle against an new BB as in her unmodernized state. Her refit had been scheduled for 1940-42 originally, but the outbreak of war put a stop to that. If I could change one thing, it would be, send the Hood to a refit in 39, and with wartime pace, she could have been ready by say mid 40. Imagine her with modernized 15"/42, better deck armour (at last) and most importantly, the excellent optics and Radar which the other ships had. She would then have handed Bismarck its head, for German Radar was no match for British one; see DOY vs Scharnhorst.
Hood would then have been present at Tokyo Bay in 45, instead of at the bottom of the Denmark Straits.
"Any relations in a social order will endure if there is infused into them some of that spirit of human sympathy, which qualifies life for immortality." ~ George William Russell
Absolutely, They make a very strong point of Bizmark being a modern "capital" ship with modern FCR where as Hood was her ancestor however being almost same size, speed, comparible guns etc. Hood was much less armored. But they still drive the point that if Hood encountered Bizmark in the open sea without cruiser protection then the battle may have gone the opposite way. Hood did have the first three shots on Price Eugan before Bizmark even replied with hers. So in essence Hood did get the jump on German ships. The rest would have been a toss of the dice and a matter of chance.
Hood was the pride of the British Navy for very good reason. Had the refit occured before wars outbreak I think she would have stood a much better chance of sending Bizmark to the bottom.
Dread,
I'm a bit confused by your recounting of this story.
Amount other things, why do they have Iowa-class battleships at Midway? Is this a "what-if"?
I mean, no Iowas were anywhere close to being ready for service in June 1942. The North Carolina and Washington hadnt even arrived in the Pacific yet.
Yes I do realize dates do not match for Midway and the Iowa's to be together (They may have been mistaken) for either the North Carolina class or the South Dakota class. (Thankx for reminding me i knew there was something not rite with the dates) And as Im finding Washington covered the Atlantic convoys in 1942 so that puts her out. I find North Carolina transfered to the Pacific June 3, 1942. And Midway was June 4-7 1942. Hmm perhaps they goofed because the ships were not ready yet perhaps it was another set of BB's.Dread,
I'm a bit confused by your recounting of this story.
Amount other things, why do they have Iowa-class battleships at Midway? Is this a "what-if"?
I mean, no Iowas were anywhere close to being ready for service in June 1942. The North Carolina and Washington hadnt even arrived in the Pacific yet.
Listed in the actual battle list are only IJN BB's. No Americans.
Then I go to another Midway page and it claims:
USS Maryland,
She emerged 26 February 1942 not only repaired but modernized and ready for great service. During the important Battle of Midway, the old battleships, not fast enough to accompany the carriers, operated as a backup force. Thereafter Maryland engaged in almost constant training exercises until 1 August, when she returned to Pearl Harbor.
In all reports of the battle of Midway it was a carrier/airpower war and destroyer/cruiser war. I guess my question is were the BB's there and not in action because of the distance to close on Midway or not mentioned because they were stand by? Or were they not there or in the ficinity at all?
Sigh, nobody with a straight answer.
Well back to fact finding
Last edited by Dreadnought; 07 Feb 06, at 18:07.
Something must be really screwy I can place most of the USN BB's at this time period except Maryland and Colorado. (Most Pearl survivors were being refitted here in the states and few in Pearl) and werent ready until late 1942-mid 1943.
Im still reviewing files for this part.
North Carolina transfered June 3 to the Pacific while Washington headed the Murmansk bound convoy's in the Atlantic. Unless North Carolina could have steamed that distance in one day but I find it doubfull. So why no written proof of this "old battleship" back up plan except for few short words?
To be truthfull I think its a screw up in recorded dates in some ways.
But I cant rule out the thought of having the Carriers at Midway without BB protection. Surely they already knew the Japanese would bring their BB's to battle with them.
Sheesh they need a new way to electronicly record history without personal bias playing a part. It would serve to eliminate fiction from non-fiction.
Ahhhh something to research and ponder.......
Last edited by Dreadnought; 07 Feb 06, at 20:03.
*Add the New Mexico class to Colorado and Maryland they were in the Pacific at that time frame.
Some of the Pearl Harbor battleships were available by June '42 (Maryland and Tennessee I believe), plus Colorado.
I'll do some checking tonight to be sure of which battleships were off the West Coast during Midway.
They were placed there on the off-chance that Nagumo and Yamamoto would pulverize Fletcher and Spruance and then continue on to the CONUS.
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