The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

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The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#1

Post by Mil-tech Bard » 15 Feb 2014, 18:31

I have been researching the radio countermeasures history of the Pacific War and found several maps and other documents that show an extensive IJA/IJN radar network through out the chain of Islands between Formosa/Taiwan and Kyushu to include Okinawa. The Pacific War chapter (chapter 15) of SUMMARY TECHNICAL REPORT OF DIVISION 15, NDRC, VOLUME 1, RADIO COUNTERMEASURES has a June-July 1945 radar coverage map of that area showing Okinawa under the radar coverage from islands to the South West and North East of Okinawa. (See attached map photos)
Japanese EW Radar Coverage -- June-July 1945 - 2.JPG
Japanese EW Radar Coverage June-July 1945
The bottom line is that these land based Japanese radars could see US Navy fighter picket stations through out the Okinawa campaign.
Okinawa Radar Picket Diagram -- SpecAttack-3-2.jpg
Okinawa Radar Picket Diagram
Does anyone know a good source on how and where those IJA/IJN radars would have _reported_ their information?

And to whom?

It does not appear that Col. Hiromichi Yahara was involved in the reporting chain at all, or chose not to mention it. The English language of his book "The Battle for Okinawa" makes not mention of Japanese radar stations on Okinawa or near by islands under 32nd Army authority.

Edward Drea makes clear in his book "MacArthur's Ultra" that the "three digit" IJA code for regimental and smaller units sizes was never broken in WW2, so any reports by IJA radar units would not be in US military intelligence Ultra code breaking records of these radar units.

Ken Kotani's book JAPANESE INTELLIGENCE IN WORLD WAR II makes clear that post-war that Japanese Army SIGINT files were extensively destroyed and the signals intelligence community told American intelligence nothing for fear of being executed.

That Japanese Radar played a large role in the Okinawa campaign is clear from the following sections from SUMMARY TECHNICAL REPORT OF DIVISION 15, NDRC, VOLUME 1, RADIO COUNTERMEASURES.

To understand the quoted passages, bear in mind the following facts:
  • The "CHI" radar listed below is the wartime US Navy code name for the post-war intelligence name "Tachi-6,"

    The Japanese Mark I radars transmitted on the same frequencies as SC and SK meterwave early warning radars on American carriers and other surface ships,

    The "Tachi-6" broadcast on the same frequency as the US Navy's TBS ship-to-ship radios.
Page 332 --

The final incident in the story of ship-borne countermeasures against enemy ground radar
came with the planning and execution of the invasion of Okinawa. An elaborate reconnaissance
of all features of the enemy defense in the Okinawa-Gunto had been carried out before
definite plans were consummated for Operation Iceberg. This reconnaissance had included radar
intercepts by aircraft, surface vessels, and submarines, as well as small-space and large-scale
photographic reconnaissance's permitting detailed pin points of several radar sites. Assessment
of this information revealed that the enemy's radar defense was probably limited to
EW equipment. A total of 10 to 12 such sets was eventually found, including the 7 listed
below:

2 Mark I Model 3
2 Mark I Model 1
2 Mark B
1 Mark CHI

In planning the operation, past experience, including Iwo Jima, strengthened the conclusion
that ship-borne jamming of EW ground radars would serve no useful purpose. Accordingly,
the operational order specified the conventional 24-hr intercept guards, with the addition
of definite jamming plans for protection against enemy airborne radar. (See subsection
entitled "Surface Vessels" of Section 15.5.4.)

and later:

Pages 333 - 334

As an adjunct to this function, the conventional intercept guards were maintained in order to discover, if possible,
the operating procedures which governed the use of enemy EW radar. Apart from the examples
of the preceding paragraph, this intercept operation further assisted by eliminating
a particularly annoying Mark CHI radar. It was discovered that this radar in the vicinity of
Chinen Saki was being used deliberately to jam the voice communication circuit of the TBS
equipment operating at 72.2 mc. Direction-finding fixes obtained from the TDY rotating antenna
were sufficient to permit low-level reconnaissance photographs to pin-point the enemy
set, and naval gunfire put it out of action.
Any help or comments would be appreciated.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#2

Post by Wellgunde » 16 Feb 2014, 04:02

1. The U.S. Navy's TBS (Talk Between Ships) radio sets were transceivers (i.e. both send and receive) which operated in the VHF frequency range between 60 and 80 MHz. They were low power (50 watts) and were restricted to line of sight communications. I would be interested to know if the Japanese targeted individual frequencies or if they simply tried to jam the entire band. The Ta-Chi Japanese radars were designed to operate at around 80Mhz. Japanese Ta-Chi radars were exclusively army.

2. Senshi Sosho Volume 11: Army Operations in the Okinawa area may have some information on radar operations.

3. Japanese Monographs No. 176: Homeland Anti-Aircraft Defense Operations Record-Western Sector and
No. 23 Air Defense of the Homeland have a good deal on early warning reporting networks and chain-of-command. I can't recall if either of them touch on the radar aspects.

4. I don't know where Drea got his info. The Japanese did not have a separate number code for "small units." There was just one system utilizing from one to five numbers for all Army units. The U.S. had managed to identify the associated numerical code for almost every Japanese army unit by the end of the war (c.f. The Signal Security Agency's Top Secret Ultra Japanese Order of Battle-1945 and the Military Intelligence Division's confidential Order of Battle of the Japanese Armed Forces, 1945). The former is extremely detailed.

5. My guess is that Yahara was either too busy or too far up the totem pole to have any direct involvement with radar operations.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#3

Post by Mil-tech Bard » 16 Feb 2014, 21:14

The best I have been able to do is get are the following:

Japanese Monograph No. 85 Homeland operations record

Japanese Monograph No.118 Operational history of naval communications, December 1941-August 1945.

US NAVAL INTELLIGENCE TARGETS JAPAN (DNI) OF 4 SEPT. 1945 FASCICLE 0-11
TARGET 0-56(N) -- JAPANESE FIELD AND AMPHIBIOUS EQUIPMENT KYUSHU DEFENSE SYSTEMS

Essentially this gives me the radar reporting of the Sasebo JNAF air defense center, which does not include Okinawa, plus a list of a few JNAF radars on islands near Okinawa but not reporting to the Sasebo JNAF air defense center.

There are no JAAF radars listed or their reporting relationships in those documents.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#4

Post by Wellgunde » 17 Feb 2014, 03:36

I don't know how much research you have already done, so if you have already done this, please forgive me.
Go here: http://www.archives.gov/research/search/ --- type in "Japanese Radar" --- from the results, scroll down and select "view all description only." There may be something there which might assist you.

I also found the following references which are probably at NARA but which may be difficult to locate:

1. SWPA: Monthly Statement on Japanese Radar Activities, various dates
2. Joint Electronics Information Agency: Locations of Radar Installations, October 28, 1944
3. Far East Air Forces: Short Survey of Japanese Radar, November 20, 1945
4. 4th Anti-Aircraft Command: Weekly Intelligence Summary No. 62, February 17, 1941 - contains information on use of Japanese Radar
5. Far East Air Forces: Intelligence Memoranda, January 1, 1945 - contains information on Japanese radar and early warning nets

Japanese command and control was "stove piped" which is to say that there were parallel reporting systems and chains of command with little sharing between components (e.g. IJA artillery radars, IJN artillery radars, IJA EW radars, IJN EW radars and possibly counter-measures radars).

Best wishes and good luck,
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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#5

Post by Mil-tech Bard » 17 Feb 2014, 04:17

I have access to the first three volumnes of the Far East Air Forces Japanese radar survey. They are technical, as opposed to operational, in nature and don't provide radar reporting organizational information regarding their use.

As for this:

>>Japanese command and control was "stove piped" which is to say that there were parallel
>>reporting systems and chains of command with little sharing between components.

This seems to be in line with Standard Japanese WW2 organization.

What I am looking for is which stove pipes fed into the Okinawa area radars reporting to which organizations outside it.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#6

Post by Mil-tech Bard » 23 Feb 2014, 22:15

Some of the information I was looking for regards Japanese land based radars in Okinawa was in Japanese Monograph No. 23 Air Defense of the Homeland.

It appears there was an air intelligence regiment under 6th Air Army that JAAF radars on Okinawa reported too.

This regiment was part of JAAF intelligence and included both Sigint units and ground observers as well as radar.

A liaison for 6th Air Army was on Okinawa and worked with Col. Yahara. He escaped to the Japanese Home Island by boat before Southern Okinawa fell. The liaison's brief was to gather intelligence on the success of Kamikaze attacks, which those radars would have played a role in getting.

While this is useful information, the general destruction of Sigint records by the Japanese army and the rumor among Sigint officers that they would be executed by the American military after surrender pretty much guarantees the Japanese Radar records of the Okinawa campaign are gone. Or at least beyond my capability to research until Senshi Sosho is digitized and put on-line in English.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#7

Post by Wellgunde » 26 Feb 2014, 04:24

Good work and thanks for the update.

The National Archives and Records Service (NARA) holds the original Japanese language versions of the Japanese Monograph series. They also have all the materials used to prepare each monograph including source documents and correspondence between the authors and between the authors and SCAP. There is also much material that did not make it into the final product (the authors did some self censorship and SCAP/U.S. Army imposed some other restrictions on what was allowable. It may well be that the "box" for Monograph No. 23 has additional material which might help you. Just a thought.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#8

Post by Mil-tech Bard » 14 May 2014, 16:52

This is a quick update to my Okinawa Radar research.

The following is typed from the after action report (AAR) of the naval invasion force commander for Kume Shima in early July 1945 --
Commander Task Group 31.24 ( ComDes Ron 63)
Subject: Action Report - Capture of KUME SHIMA, Okinawa Gunto, 25-27 June 1945

----
6. Conclusion

Destroyers who hare done Radar Picket duty around Okinawa the past three months
have long been suspicious of KUME SHIMA. Bogies seemed to appear if by magic, from the
shadows of this island; and on the few occasions they were able to use a round trip ticket,
disappear as strangely into KUME.


The landing strip, immediately behind Green Beach, contained a number
of wrecked planes. indicating it my have been used for emergency landings. The
strip itself, however, was reported to be in such poor shape that it could hardly
have been used as an operational or even staging field. It seems probable that a
radar and radio on KUME SHIMA served as a beacon to bogies approaching
the Okinawa Area from the south and west.


The destroyers, then, perhaps more so than any other units, will be
glad to see this island out of enemy hands. It should make a first
rate, unsinkable Radar Picket, and soon relieve the destroyers of their vigil
along the FORMOSA-OKINAWA Air Highway."
----

Since I finding that "datum," I've also run down the Okinawa Island Command (IsCom) G-2 report of the capture of the Tachi-6 radar, the Fleet Marine Recon battalion report of their over running a heavy machine gun position manned by this radar's crew, as well as the USMC line company AAR speaking of capturing the radar.

The existence of Japanese radars inside the US Navy's destroyer picket screen at Okinawa is certainly _not_ in the institutional historical narratives of the US Army, US Air Force, US Navy or US Marine Corps for Okinawa.

It now appears that this omission by those histories, as well as by the classified OSRD Division 15 radio-countermeasures history, can only be described as "by the conscious choice" of the Navy Department. They were the custodian of all the non-Division 15 OSRD records I've accessed in my research.

Whether this omission was simply a "Ultra must be kept secret" classification-type omission or more parochial ass covering is still an open question in my book. The fact that US Navy snoopers couldn't locate the Tachi-6 isn't surprising, as the Central Pacific Campaign was dealing with Japanese Navy Radars. While MacArthur's New Guinea-Philippines line of advance was dealing predominantly with the Japanese Army radars after Rabaul was by-passed in Early 1944.

The Division 15 radio countermeasures omission is serious and supports the "by the conscious choice" scenario as the fact that US Navy's signals intelligence aircraft could not home of Tachi-6 radio signals would be a major after action finding.

In another USN AAR document by the 5th Amphibious Force -- "Report on OKINAWA GUANTO OPERATIONS from 17 February to 17 May 1945" -- It was reported that the Japanese night time snoopers were so regularly shaking off US Navy and USMC radar equipped fighters that Adm. Turner gave them permission to turn off their IFF. This was because night fighter pilots thought that their IFF being triggered by equipment on Japanese snoopers.

Turning off the IFF had no effect on Japanese evasive action.

The key thing for me is that despite that American night fighters still ran up a good score on these night snoopers...just not as good as these pilots thought they should.

Suppose we have an issue of Japanese Army Air Force versus Japanese Naval Air Force radios? They were different, and did not communicate with one another, after all.

That means when American night fighters got close to JNAF snoopers, they could get the kill.

When they got near JAAF snoopers, the Kume radar could have told them to take evasive action.

Unfortunately this does not seem to be testable with available Japanese operational records. The real problem is a lack of Japanese military records from the time. The 32nd Army's commander did a darned fine job of destroying Japanese documents to deny their intelligence value to the American G-2. This was remarked upon on the primary histories extensively. Between Surrender and Occupation Japanese Army Military Intelligence -- particularly it's Signals Intelligence units that Radar was parked in administratively -- did the same.

This makes a test of these two obvious hypothesis:

1) "Was American night fighter performance near JNAF different from JAAF for night operations?," or

2) "Was American night fighter performance near the snoopers differed from results away from the snoopers"

....nearly impossible.

There are at several other confounding factors with such tests unrelated to those Japanese records --

1) Fighter Director (FD) competence -- There were six land based GCI night fighter control stations involved in the Okinawa campaign as well as 19 USN fighter director teams, plus re-enforcement/replacement FD Teams, on the Naval pickets.

2) Night Fighter Squadron competence -- There were three USMC and one Army night fighter squadron land based units with one of the USMC squadrons being Solomons campaign old sweats. Before 15 May this work was done by USN carrier based squadrons. Enterprise was the Night Carrier for TF 38 during the Okinawa campaign and she caught a Kamikaze 11 April and again on 14 May 1945 after repairs and travel got her back to combat on 6 May 1945.

3) Japanese Radars and listening posts on Okinawa. There were both Army and Navy radars there in the time period of the report and it was standard procedure for listening posts to be associated with them. There was in fact a Japanese strategic listening post tower identified in a Jan 1945 US Navy reports as being at Naha, Okinawa.

4) Last and most important, Japanese Kamikaze Operations records are again...problematic. Tadashi Nakajima's and Roger Pineau's "The Divine Wind", has a few interesting points in it:

For Kikusui No. 2 (attacks on 12-13 April 1945), of 185 aircraft taking part, only about 80~ were kamikaze; more than a hundred were escort fighters whose job was to:

A.) Provide navigational leadership for the untrained kamikaze pilots -- in effect saying "Hey there, follow me to your target,"
B.) Protect them wherever possible from enemy fighters,
C.) Provide Bomb Damage Assessment on the kamikaze strikes either via radio or flying back at the end of the mission.

Unfortunately for such hypothesis tests; 3rd, 5th, and 10th Air Fleets didn't bother to keep track of the breakdown of escorts and Kamikaze attack craft (these were the units involved with Okinawa operations); but other units did, leading to these numbers from the

Appendixes of THE DIVINE WIND:

Recapitulation--Philippine Islands Area

JAPANESE NAVAL AIRCRAFT

KAMIKAZE PLANES

Sortied 421
Returned 43
Expended 378

ESCORT PLANES

Sorted 239
Returned 137
Expended 102

TOTAL 480

-------------

Recapitulation--Formosa Area

KAMIKAZE PLANES

Sortied 27
Returned 4
Expended 13

ESCORT PLANES

Sortied 18
Returned 13
Expended 5

-------------------------

Recapitulation--Okinawa Area

(Owing to differences in administrative procedures, no breakdown
between kamikaze and escort planes is available for 3rd, 5th, and 10th
Air Fleets)

PLANES

Sortied 1809
Returned 879
Expended 93
----

So, I have this really great history story, even if I can't close the loop with a Japanese source "flaming datum" for the use of the Kume Radar...so where do I get it published professionally?

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#9

Post by cstunts » 18 Aug 2014, 04:53

Hello,

For the record "TBS" was the official designation for that series of equipment type; it was not originally an acronym.
"Talk Between Ships" was added subsequently to provide a mnemonic device for it as an acronym...

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Camp

#10

Post by Wellgunde » 18 Aug 2014, 07:49

The first TBS radio set was introduced in 1938. If I recall correctly, the first contract was let to RCA. The TBS went through nine revisions: TBS through TBS-8. In the years just prior to World War II and for several years after, the USN used a three letter system for electronic equipment nomenclature. The first letter indicated the broad equipment type, for example "F" for facsimile, "R" for receivers, and "T" for transmitters. The second letter, usually but not always, indicated a refinement of equipment purpose. All radio equipment with designators starting with the letters "TB" were transmitter-receivers. The third letter indicated the equipment series. The TBS was not the only transmitter-receiver used for inter-ship line of sight communications during World War II. The fact that the TBS series was the most common equipment used for "talking between ships" is just a coincidence.
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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#11

Post by Mil-tech Bard » 04 Dec 2014, 21:18

From IJA Radar topic --
Re: IJA Radar
by Wellgunde » 02 Dec 2014, 00:46

I am impressed by your research on this subject. As we discussed, a lot of important factors seem to have fallen through the cracks before and during the Okinawa campaign. Who was doing the actual radar signature collection? There also seems to be a very considerable time lag between collection and promulgation of the information to the operating forces. Another question which comes to mind is exactly what were the capabilities of the primitive combat information centers on World War II USN ships?
I'm going to point to the following --

http://www.ibiblio.org/hyperwar/USMC/V/ ... .html#cn67


Victory and Occupation
History of the USMC in WW2

Chapter II-5
Phase I Continued


Enemy air attacks on shore installations were directed at Yontan and Kadena airfields mainly, and usually took place at night. The only firing opportunities afforded shore-based antiaircraft artillery during daylight occurred when Japanese aircraft, with the obvious intention of attacking the transport area, made their approaches from the landward side of the anchorage.67 Usually, the illumination or visual sighting of an enemy plane, and sometimes even an American one, was the signal for a wave of wild uncontrolled firing both from shipboard and the island. "Carbines, rifles, and even .45 caliber pistols enthusiastically joined the fun on occasion."68 Under these conditions, casualties and materiel damage resulted from falling shell fragments and wild shots until the Tenth Army insisted upon the enforcement of greater fire discipline by all unit commanders.

From the beginning of ADCC operations, there was no satisfactory communications and control system linking the fighter command and the antiaircraft artillery units. When ADC was heavily engaged with enemy air attacks, liaison with AAA units weakened or broke down completely. At times, permission for the guns to fire on unidentified or enemy planes was withheld, even when the area was definitely under attack. On several occasions, air raid warning flashes were not relayed to the AAA command until after the infantry and shore party units had been informed.69 Of necessity, an efficient control system was soon initiated. By the end of the month, Marine AAA units were credited with the destruction of 15 planes and 8 assists, 5 probably destroyed, and 6 damaged.70

--184--

It was noted that, during enemy air attacks, Japanese aviators showed an increasing knowledge of radar evasion measures, and frequently used "window"71 in both conventional and Kamikaze attacks. In commenting on the enemy failure to mount air attacks on the ground forces, one observer stated that "it was difficult to understand why they had not resorted to formation bombing from low altitudes,"72 since low-angle radar detection of approaching aircraft was almost impossible. He concluded that the concentration on suicide attacks was too great; he might have added that the Japanese just did not have enough planes by this time to divert their air strength to missions other than the Kamikaze attacks.


While the above passage is somewhat true. The 10th Army Tactical Air Force and Anti-aircraft passages of the Okinawa Phase II After Action Report are far more scathing and plant the blame for the above on Admiral Turner's ham fisted control of the rules of engagement.

An even harder hitting description of the issues with Turner can be found in the JULY-AUGUST, 1949 issue of the US Army Coast Artillery Journal on pages 2-10 in an article titled "Activities of the Tenth Army AAA." The CAJ was running a series on the combat experiences of the various AAA Brigades and the 53rd AAA Brigade combat experience on Okinawa was spotlighted here.

See this passage from the article --

On the evening of 20 April, between 1911 and 2335,
the enemy, staged an extended air attack with more than ~
50 planes, the bulk of which penetrated the gun defended
area on Okinawa. This operation portrayed vividly some
inherent problems in combined fighter-AAA defense of an
area from which planes have to operate. Day fighters used
both fields; night fighters operated from Yontan. The
fighter screen was dispatched from both fields to the vicinity
of the outlying radar picket ships at a radius of about 70
miles. Day fighters were landed at dusk and night fighters
were "scrambled" and "pancaked" at odd intervals all night.
It was the practice of the air defense controller to withhold
AAA fire when friendly planes were overhead, regardless
of the comparative effectiveness of fighters and AAA.

Jap pilots soon learned to follow our fighters in and bomb
the airfields while AAA was in Control GREEN and not
permitted to fire. On this night they did exactly that with
unusual success. The area containing Yontan and Kadena
airfields and the landing beaches was the main objecti,'e of
six separate raids, flown about 45 minutes apart. \Vindow
was dropped a number of times. The third raid was tracked
at 17,000 feet; the others at from 100 to 1000 feet. During
the course of the attacks some of the enemy Hewlow over the
airfields with running lights on, circli~g the field with
friendly fighters. They strafed, and dropped approximately
40 incendiary and high explosive bombs. Fires were started
on both airfields, necessitating the evacuation of one 1\larine
AAA 40-mm gun position. During the entire period. 1\1\A
was held in Control GREEN except for 15 minutes when
no enemy planes were in the area. The only AAA firing
was by automatic weapons at strafing planes.

After this episode the AAA Commander conferred with
Commander Air Support and achieved some improvement
in the handling of fighters so as to facilitate the release of
AAA fire when required. Favorable results were first demonstrated
on the night of 27-28 April when the enemy renewed
his aerial activity over Okinawa. Aided by clear
weather and a full moon he struck in force at Yontan airfield.
Seven raids between 2053 and 2400 reached the
gun defended area. A large quantity of window was dropped
and the use of IFF by the japs was reported. Air defense
control was excellent and friendly fighters were held out
while enemy planes were within range of the AAA. Four
planes were destroyed and one probably destroyed at altitudes
from 3000 to 9000 feet. This attack on Yontan carried
over into the early morning with two raids at 0252 and
0301. The first, a bomber at 19,000 feet, was shot down on
his third attempted bombing run. The second raid of two
planes, one fighter very low and one bomber at 6000 feet,
made unsuccessful attacks on Yontan. The fighter was destroyed
and the bomber driven off.


The "Commander Air Support" was Adm. Turner.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#12

Post by Mil-tech Bard » 04 Dec 2014, 21:40

See also this from --

Victory and Occupation
History of the USMC in WW2
Chapter II-11
ICEBERG Dissolves

...where Adm Nimitz was less than pleased with Turner's performance as Okinawa's Air Commander:
At this time, existing airfields on Okinawa were expanded, and new ones built at Awase on the east coast and Chimu in the north in accordance with base development planning. The influx to these and the other fields of newly joining squadrons increased ADC aircraft strength from 432 planes at the beginning of June to 711 at the end.20 With these additional aircraft, TAF mounted increasingly stronger air attacks against the Japanese Home Islands. Marine fighter planes from ADC hit Kyushu installations for the first time on 10 June, the day before Major General Louis E. Woods relieved Major General Mulcahy as TAF commander.21

There was little change in the missions of TAF, Ryukyus Command, from those it had fulfilled as an agency of the Tenth Army. On 1 July, when the command change occurred, ADC assumed complete responsibility from TF 31 for the air defense of the Ryukyus. At this time, TAF aircraft strength was substantially increased, especially by the bomber squadrons, and General Woods could send his planes to better objectives further away from Okinawa than those attacked previously. In its first raid under TAF, on 1 July the 41st Bombardment Group sent its Mitchell bombers to blast Kyushu. On that same day, TAF inaugurated a combat air patrol over Kyushu in hope that Japanese pilots would take off from island airdromes to engage the American planes. Few enemy pilots rose to the occasion.

In another phase of TAF operations, Thunderbolts began hitting Japanese installations on the China coast near the Yangtze Estuary on 1 July. A landmark

--372--

in TAF operations occurred on the 9th, when B-24s attacked Japan from Okinawa. All together, the 47 heavy bombers--and the 25 Mitchells and 32 Thunderbolts acting as bombers accompanying them--spread 1,880 clusters of fragmentary bombs and 280 clusters of incendiary bombs over dispersal areas and field installations of Omura airfield on Kyushu. Another 92 Thunderbolts escorting the mission acted merely as spectators; no enemy interceptors appeared.

In accordance with orders from CinCPOA, TAF, Ryukyus was dissolved on 14 July.22 On that date, all Marine air units reported to the 2d MAW, which was then designated Task Group 99.2, and assigned to the Ryukyus Command. AAF squadrons and groups that had been temporarily assigned to TAF were transferred to the Far East Air Forces (FEAF), which assumed control of the mounting number of air attacks against Japan.

Under the Ryukyus Command, Marine squadrons continued flying the types of missions they had flown previously, but they now ranged much further away from the island than when they had been committed to the air defense of ICEBERG forces. On 19 July, ADC flyers made their first visit to the China coast, when 59 F4Us flew cover for TF 95, then operating off the enemy-held littoral.23 At 0001, 1 August, the 2d MAW and all of its squadrons with the exception of VMTB-131 and -232, and VMB-612,24 passed to the operational control of FEAF; the three other squadrons were assigned to the control of Fleet Air Wing 1.25
and particularly these footnotes where Nimitz's ire is very clear --

21. "My assignment as General Mulcahy's relief was a most unexpected one for me. I was in Pearl waiting to see [Major] General [Ralph J.] Mitchell, whom 1 was relieving as CG of the First Air Wing, then at Bougainvillea,when AirFMFPac gave me immediate orders to go there. I took off with double crews and flew continuously until arrival. Upon arriving, I reported to General MacArthur's Headquarters by dispatch. Several hours after my arrival I received immediate orders to proceed to Guam and to report to Admiral Nimitz. I did as ordered and Admiral Nimitz personally briefed me, and told me to take the necessary steps to have the ADC of TAF take over the air defense of the area in the very near future as the losses from the Kamikaze attacks were heavy and he was going to withdraw all ships as soon as possible. Upon my arrival [at Okinawa], I found that Admiral Hill and his flagship were responsible for the air defense of the area, and that the ADC of TAF was really only a fighter command and not responsible for keeping track of friendly aircraft in the area. When I took command . . . I ordered the ADC to get set up to take over the complete responsibility for the air defense . . . without delay. . . . Why the ADC hadn't been called upon to [keep track] of the friendly planes in the area long before this has always been a mystery to me, for how can an outfit provide air defense properly unless it has full information about all friendly and enemy aircraft in the area?

To deepen the mystery was the fact that it has been reliably reported to me that neither AirFMFPac nor Headquarters Marine Corps knew of my being sent to Okinawa until after my arrival." Wood ltr I.
and
25. 2d MAW WarD, Jul45. Before this change took place, General Stilwell had received a different set of orders from CinCPac headquarters concerning the future disposition of the 2d MAW. According to Admiral Nimitz' first directive, which assigned ". . . all the Fighter Squadrons to the [FEAF] Fighter Command, and the VMTB squadrons to the Fleet Air Wing. That left only my [General Woods] command headquarters without any units . . . under General Stilwell. On the last day I was under his command, I went . . . to see him. and told him I was a General 'without portfolio' and asked permission to fly to Guam. I told him that I would be back in command of the units of the Wing or I wouldn't be back. He wished me luck and I left. When I got to Guam, I saw Vice Admiral [Charles H.] McMorris [CinCPac Chief of Staff] and after some discussion all units were returned to my control and new orders were issued." Woods ltr I.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#13

Post by Mil-tech Bard » 07 Dec 2014, 18:07

This is the first of several posts for unifying data gathered on other AHF threads regards IJA/IJN radar at Okinawa

Post 1 of several --

See the following link and text regards the date of capture of the Tachi-6 on Kume Jima.


http://kumejima.warwickhi.com/Marinestakekume.html
Company "A", 1st Battalion, 7th Marines,
1st Marine Division(1)
30 July, 1945

July 2, 1945

At approximately 0330 the 81-mm fired a harassing mission and the enemy returned the fire by spraying the bivouac area and defensive perimeter with two 13.2-mm dual-purpose MG's. The 81-mm fired two missions and neutralized the enemy machine guns. One strecher bearer was critically wounded and died as a result of wounds received from enemy fire.

A coordinated attack was launched at 0730 on the enemy position on the peak at TA 7390-0 by Company "A", Amph Recon Bn. moving south from road at TA 7391R and south. Company "A", 7th Marines, moved west along the ridge from hill at TA 7591-U. Company "B", Amph Recon Bn., was deployed with combat groups on a line generally from TA's 7290-Y-5 to 7290-N. The attack was preceded by preparatory fire from two 75-mm howitzers (LVT(A)'s) and the 60-mm and 81-mm sections. The attack progressed against inaccurate enemy rifle fire; movement was across extreemly steep and rugged terrain where thick vegetation hindered both movement and observation. By 1400 the enemy positions were completely overrun. The bulk of the ememy holding force is believed to have withdrawn and scattered in the wooded area in TA's 7489, 7589, and 7689. Two heavy MG's, caliber 13.2-mm were captured intact by Able Company, 7th Marines. The enemy is estimated to only have one MG, and it has been removed from a crashed plane, probably 7.7-mm.

Enemy radar equipment was destroyed by Able Company, 7th Marines. All troops returned to initial beachhead and occupied their original defensive positions.

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#14

Post by Mil-tech Bard » 07 Dec 2014, 18:23

2nd post of several --



Re: IJA Radar
Post by Wellgunde » 21 Oct 2014, 13:20

The bit about the P-47s was in U.S. Army Air Forces in World War II - Combat Chronology (1941-1945). You can download a PDF here:
http://www.afhra.af.mil/shared/media/do ... 29-036.pdf

It's hard to accept a conspiracy for the deletion of Kume Jima although such things have happened. I think bureaucratic ineptitude, wishful thinking, misfiled reports, fog of war, or a host of similar reasons might be likelier causes. MIS Colonel, "Where's the radar report?" MIS Captain, "We're waiting for confirmation on Kume Jima." MIS Colonel, "We're a week over the deadline; just leave it off and we'll figure it out later."

That's a good catch by the way.


and



Re: IJA Radar
Postby Mil-tech Bard » 21 Oct 2014, 16:36

Wellgunde,

I am not big on conspiracies, either.

However, Brass hats "covering their anatomy" when post-war budgets are afoot is a completely different matter.

I have checked against both the 10th Army invasion of Kume Jima and Summary Technical Report of Division 15, NDRC, Vol. 1, RADIO COUNTERMEASURES, Chapter 15 (Pacific radio countermeasure operations) and the Kume Jima radar was not in either.

Tenth Army's report, part 2 of Capture of Okinawa Gunto, did mention a _RADIO_ on Kume Jima...but this was after the Fleet Marine Recon Battalion; Able Company, 7th Marines July 1945 War Diary; Commander Task Group 31.24 ( ComDes Ron 63)'s
Action Report - Capture of KUME SHIMA, Okinawa Gunto, 25-27 June 1945; and the Island Command (ISCOM) Kume Jima said _RADAR_.

In fact see:
Commander Task Group 31.24 ( ComDes Ron 63)

Subject: Action Report - Capture of KUME SHIMA, Okinawa Gunto, 25-27 June 1945

>much snipped<

6. Conclusion

Destroyers who hare done Radar Picket duty around Okinawa the past
three months have long been suspicious of KUME SHIMA. Bogies seemed to appear
if by magic, from the shadows of this island; and on the few occasions they were
able to use a round trip ticket, disappear as strangely into KUME.

The landing strip, immediately behind Green Beach, contained a number
of wrecked planes. indicating it my have been used for emergency landings. The
strip itself, however, was reported to be in such poor shape that it
could hardly have been used as an operational or even staging field. It seems
probable that a radar and radio on KUME SHIMA served as a beacon to bogies
approaching the Okinawa Area from the south and west. The destroyers,
then, perhaps more so than any other units, will be
glad to see this island out of enemy hands. It should make a first
rate, unsinkable Radar Picket, and soon relieve the destroyers of
their vigil along the FORMOSA-OKINAWA Air Highway.


The one thing the release of the Nimitz War Diaries make clear is that the founding of the Defense Department was very much on the minds of Senior Naval Brass in planning and executing the Okinawa campaign.

In fact, it seems to be a large reason why the USAF's 7th Air Force was cut out of commanding land based air operations on Okinawa in favor of the USMC commanded "Tactical Air Force -- Tenth Army."

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Re: The Role of IJA/IJN Land Based Radar in the Okinawa Campaign

#15

Post by Mil-tech Bard » 07 Dec 2014, 18:34

Re: IJA Radar
Post by Mil-tech Bard » 20 Oct 2014, 13:32

What I have found interesting is the way that the Kume Jima radar seems to have been wiped out in terms of US Navy reporting to the War Department in Washington DC.

The following picture is from:

JAPANESE RADAR LOCATIONS,
RATEL No.11
July 1945
Military Intelligence Division
War Department
Washington DC.

Japanese Radar in Okinawa Area After Okinawa Fell --Ratell 11 -- Jul-1945 - 1.jpg

(picture not included in post)

Based upon this and the OSRD Division 15 report on Radio Countermeasures, it sure looks like the Navy Department was trying to hide the existence of the IJN Kume Jima Radar and the implications of it for the post-war reputations of the USA Navy brass involved in running the Okinawa campaign.

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