Tokyo Kanigaya
POW Camp (Detached),
Radio Station Listening Post

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Tokyo Kanigaya Detached POW Camp


Satellite map
Aerial photo 1 (July 1947) - photo 2 (Feb. 1948); courtesy of Japan Map Archives

Jun 1930: Radio station established
17 Apr 1942: Established? as Kanigaya Detached (Temporary) Camp; four American POWs transferred to camp from Ofuna for use in monitoring overseas broadcasts
10 Aug 1942: Two Americans from USS Pope and five British HMS Encounter and HMS Exeter transferred to camp from Ofuna
Aug? 1942: Three POWs from USS Perch transferred to camp from Ofuna
1943: Operations moved to reinforced concrete underground bunker
19 Apr 1944: Death of Robert Shilton
22 Oct 1944: Death of Franklin Kidd
Aug 1945: Closed; POWs evacuated to Ofuna camp

Imperial Navy
Tokyo Signal Corps,
Kanigaya Detachment

In June 1930, the Imperial Japanese Navy established a shortwave radio base in Kanigaya, Takatsu-ku, and in 1937 was renamed the "Tokyo Naval Communications Unit, Kanigaya Detachment."

The Tokyo Naval Communications Unit was divided into the Funabashi (Chiba) and Totsuka (Yokohama) Detachments, which were tasked with signal dispatch (transmitting), and the Kanigaya Detachment, which was tasked with signal reception (receiving).

In 1943, as the war intensified, two reinforced reception stations (underground bunkers) were built in this valley, which at the time was surrounded by forests and bamboo groves. It was the only one of its kind in Japan, equipped with the highest level of technology.

It is said that they intercepted information from around the world as well as the offensive and defensive operations of the Japanese Imperial Navy, and relayed the information (via a 2-km-long underground cable) to the Tokyo Signal Corps Headquarters and the Combined Fleet Headquarters, which was located underneath the campus of Keio University in Hiyoshi, Yokohama.

The site was extensive, consisting of 22 buildings and 6 antenna towers along with many other smaller utility poles on 46 acres of land, and equipped with twelve large shortwave receivers, one oversized longwave transmitter (said to be the only one of its kind in Japan), and two 250W medium-wave transmitters.

When the naval forces were outnumbered in 1943, the Kanigaya detachment proceeded to improve its air defense facilities and built 40cm-thick concrete underground monitoring centers to prepare for air raids (a 100-meter-long tunnel still remains today). More than 200 Japanese personnel worked there, and about 30~40 POWs from Britain and the United States (and Australia?) were assigned to monitor overseas broadcasts and relay that information. This information was transmitted to the headquarters of the Tokyo Signal Corps and the headquarters of the Combined Fleet, which was located on the campus of Keio University in Hiyoshi, Yokohama.

The bunker had three entrances, and the large room was the telegraph room where a lot of communication equipment was placed. The power generation room was on the left. The bolts and high-voltage insulators where the engine and generator were installed still remain, according to the report.
Layout of bunker

* Lt. Yamada - officer in charge of POWs for first two years
* Lt. Cmdr. Uchiyama - captain of radio station
* Lt. Cmdr. Souda - became captain of radio station after Uchiyama
* Tanabe (Petty Officer) - guard for entire 3 yrs. and 4 months POWs were at the camp


* Kanigaya Radio Station map - circle X's = towers, X's = antenna cables, structures = soldier barracks
* Kanigaya Radio Station
(from Japanese book, Encyclopedia of War Ruins)
* Kanigaya Radio Station 1958

Memo from Lt. Cmdr. Blinn to US Occupation Forces investigations team:
I spent 19 months at Ofuna Navy Camp without becoming a POW (from April 26 1942 to Dec 3 1943. Lt Whiting USN 20 1/2 months in same status from 1 May 1943 to Jan 15 1945).
From Ofuna about June 1942, two radiomen from the USS Pope and several from the USS Perch and HMS Exeter were transferred for radio duty. No record so far as I have found in Tokyo has been made by these men. One of the USS Pope's radioman's name was Borkowski RM2/c.
Be sure and investigate records of Ofuna and Bunka, both unofficial P.O.W. camps and entirely unlawful.
W. C. Blinn, Lt. Comdr.
US Navy, USS Pope

Similar to the Bunka Camp (Radio Tokyo), this was an even more "secret" camp and radio station which utilized POWs skilled in radio communications to assist with monitoring overseas broadcasts (note in roster below all the men's ranks were Radioman and Telegraphist).
NOTE: Initially the POW "captives" were at Ofuna (a detached interrogation camp under control of the Imperial Navy) and were illegally transferred to Kanigaya, not for interrogation but to work FOR the Japanese Navy in intelligence gathering. Only when captured enemy combatants were handed over to Army control did they officially become prisoners of war.

Per information from Marvin Ballhorn:
Ballhorn and others were taken off the Nitta Maru at Yokohama and then were taken to a house for interrogations that an oil company representative had owned/occupied. They learned that the Japanese wanted them to work for them receiving messages.  They were concerned this might be considered treason. They talked to their officers and were told to receive messages was not, but that to transmit messages could be. Since they were only being asked (told?) to receive messages they didn't need to worry. They encouraged them to do it to keep them from other types of back-breaking work. Balhorn noted that when they received the messages, they altered them so that no critical information was ever recorded.

The other concern came about later. They ended up being paid for their work, 6 yen a month. Though it may appear as if they were employees and voluntarily doing the work, that wasn't the case -- it was their only means to get necessities like soap and toothpaste, and there was never any left at the end of the month.

POWs were kept in two large bunkrooms.  A monitoring station (with receivers and typewriters) was set up in a corner of the radio station. Later the Japanese moved them all into one bunkroom and used the second one as their monitoring station. No reason was given. The radio station was also used as a training station for kamikaze pilots, training young teenagers like a boot camp.

POWs were tasked with copying code on various frequencies (NPM, NPG, NPN Fox Schedules, the Admiralty Island and Guam Schedules, China, submarine, distress, ship-shore, and aircraft frequencies).

NOTE: Per a Japanese website, the kamikaze pilots were sent to Kanigaya as there were no planes available for them to fly. One former worker remarked that there were Allied messages saying that "Japan is going to lose the war."

Fourteen Allied POWs were known to have worked at the radio station in Marvin Ballhorn's group (this information courtesy of Rita Merta, daughter of Ballhorn):

* Ballhorn, Marvin William - RM3C, USN, NAS Wake
* Besancon, Victor Clarke - RM1C, USN, NAS Wake
* Sargent, Charles Alfred - RM1C, USN, NAS Wake
* Kidd, Franklin Benjamin - RM3C, USN, NAS Wake - died at Kanigaya 22 Oct 1944, stomach cancer
(These four men were transferred from Ofuna to Kanigaya on 17 Apr 1942.)

* Borkowski, Edward Joseph - RM3C, USN, USS Pope (DD-225)
* Sibert, Lawrence James - RM2C, USN, USS Pope (DD-225)
(These two men were transferred from Ofuna to Kanigaya on 10 Aug 1942.)

* Berridge, Robert Channing - RM3C, USN, USS Perch (SS-176)
* Normand, Joseph Raymond - RM2C, USN, USS Perch (SS-176)
* Reh, Theodore John - RM1C, USN, USS Perch (SS-176)
(These three men were transferred from Ofuna to Kanigaya - date unknown.)

(As listed in the book, Remembering Billy - A Daughter's Memories of a Far East POW Survivor)
* Hunt, Ronald Albert - Petty Officer Telegraphist, HMS Encounter
* Megraw, William Harold Annesley - Telegraphist, HMS Exeter
* Newman, Harold Edward George  -  Chief Petty Officer Telegraphist, HMS Exeter
* Schofield, Norman Neville - Lead Telegraphist, HMS Exeter
* Shilton,Robert Percy - Petty Officer Telegraphist, HMS Exeter - died at Kanigaya 19 Apr 1944, peritonitis
(These five men were transferred from Ofuna to Kanigaya 10 Aug 1942.)

* Statement of Marvin Ballhorn (19 Sept 1946)
* Lt. Cmdr. Ikutaro Kobayashi statement - chief surgeon at Kanigaya re deaths of Kidd and Shelton
* CPO Kakuzo Iida affidavit - Ofuna Detached Camp commander from Sept. 1942, mentions 14 POWs sent to Kanigaya
* G-2 Division: Japanese Military and Naval Intelligence Interrogations Report, Nov-Dec 1945 (Part A - Part B) - interrogations of 51 Japanese Navy and Army officials on a variety of topics dealing with military intelligence. Of special note are remarks and report by Rear Adm. Takeuchi re intel gathered from POWs.
* G-2 Division: Japanese Military and Naval Intelligence Report, Nov. 1945 to Jan. 1946 (Part A - Part B - Part C) - evaluation of Japanese intel: organization, procedures and effectiveness. Of note is info on radio communications intelligence (from Part A, p. 53).
* G-2 Division: Memorandum for H. R. Thurber to Rear Adm. Ofstie: Comments on Japanese Military and Naval intelligence Report - recommended edits to above document (Part A)
In Japanese only:
* Kanigaya Radio Station - Notice of Land Purchase 1929-12-14
* Kanigaya Radio Station - Antenna and building blueprints 1930-12-05
* Kanigaya Radio Station - Land Management Transfer, property maps 1933-07-26 to 1934-12-06

* Remembering Billy - A Daughter's Memories of a Far East POW Survivor by Stanley Robert Megraw, Kathryn Jane Bollom - book about William Megraw, gives details about the Kanigaya radio station

* Museum (Kawasaki Heiwa-kan "Peace Hall") - special exhibit on Kanigaya including a 1/35th scale diorama of the underground site (in Japanese only)
* Japanese Radio Communications and Radio Intelligence (Jan. 1945) - includes photos of radio sites with antenna towers