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
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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."
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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
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Recapitulation--Formosa Area
KAMIKAZE PLANES
Sortied 27
Returned 4
Expended 13
ESCORT PLANES
Sortied 18
Returned 13
Expended 5
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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
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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?