OP-20-G Collection Efforts against the Japanese Imperial Fleet:
Prior to 1932, OP-20-G, the Code and Signal Section, a Division of Naval Communications was focused on intercepting VLF and LF Japanese Imperial Fleet communications that originated out of the Japanese Naval Ministry in Tokyo as well as HF point-to-point circuits between major navy radio stations throughout Japan. Additionally, communications were intercepted between Formosa (known today as Taiwan) and Tokyo and between Tokyo and senior Flag officers assigned to the Japanese Expeditionary Force operating in China coastal waters.
Japanese Imperial Fleet was organized into the 1st, 2nd and 3rd Fleets, consisting mainly of battleships, cruiser/heavy cruisers, destroyers and submarines that were home ported at Yokosuka, Kure, Osaka, Sasebo and Ominato naval bases and Aircraft carriers home ported at Kagoshima. A substantial volume of radio traffic was passed among these commands on fleet communications between 100-400 KHz using low power transmitters. This was to prevent unintended interception of their communications.
The vast majority of the communications that were intercepted were accomplished at OP-20-G shore units located at Oahu Hawaii, Guam, Philippines and at the 4th Marine HQ in Shanghai, China. Unfortunately, afloat communication intercept operations were poorly staffed and deployments occurred intermittently onboard USS GOLDSTAR (AK-12), USS PITTSBURGH (CA-4), USS AUGUSTA (CA-31), and USS ISABEL (PY-10).
Lack of Intercepts:
Although OP-20-G traffic analysis enabled them to reconstruct the Japanese Imperial fleet order-of-battle and Command and Control, there was a large volume of communication that was not being intercepted. Except when the Japanese Imperial Fleet conducted naval operations and exercises in international waters, those low powered communication circuits could not be intercepted. As a result, OP-20-G traffic analysts were prevented from establishing a complete frequency usage table, call sign system and other critical details of the Japanese Imperial Fleet.
In order to overcome the lack of communications intercepts needed, OP-20-G, in early 1932 developed a plan to establish a covert communications intelligence (COMINT) intercept effort aboard ships while transiting the Japanese coastal waters that was directed specifically at the Japanese Imperial Fleet low powered communications operating in the 100-400 KHz range.
During this same time, HQ U.S. Weather Bureau, a Department of Commerce, now known today as the National Weather Service, was seeking a means to obtain information on the formation and speed of weather systems moving from west to east across the North Pacific. Because of the shared interest in weather, the Department of Commerce approached the Department of the Navy to discuss the situation along with their concerns and requirements. Probably after several meetings, OP-20-G and Weather Bureau combine their efforts toward to developing a proposal to American President Line (APL) shipping company asking to use four of their ships as platforms for a Pacific Ocean upper-air weather project.
After department level conferences were arranged between representatives of government and APL the the following agreement was established:
For payment in kind, the APL would transport, room and provide meals for approximately one Year’s time (May 1933 – June 1934) for four USN radiomen and four U.S. Weather Bureau aerographers. Four APL vessels assigned the Seattle-Manila round trip run would be involved with one radioman and one aerographer transported as first class passenger status in each vessel. The two man team in each vessel would conduct a weather research project for duration of the agreement.
A temporary shelter was built by APL on the weather deck of each ship, which was designed to store aerographers equipment, such as a theodolite, tripod, cylinders of hydrogen gas and a large supply of uninflated weather balloons.
Each radioman received permission from the ship’s captain to string an antenna near the outboard rail of weather deck. The antenna transmission cable was placed over the side of the ship and routed through the porthole of radioman’s cabin one deck below. As a cover for the radioman operation, this transmission cable was connected to a small AC/DC AM broadcast receiver for leisure listening: music, newscast, Amos and Andy, etc.
Aerographer-Radio Joint Mission:
Twice daily, at 0800 and 1600 (ship’s local time), weather balloons were inflated, released and then tracked using the theodolite until the balloon was no longer visible. The aerographer tracked the balloon while the radioman recorded the data. After all data was collected, the aerographer encoded the information such as altitudes, bearings, times, surface level weather conditions and ship’s position in a message.
Because of the agreement between the government and APL, the radiomen used the ship’s transmitter to send the message over ship-shore commercial radio to either KTK in Mussel Rock CA, KFS in Pale Alto CA or KPH in Bolinas CA for relay to US Weather Bureau HQ, Washington D.C. This action justified the requirement for the radioman to be onboard.
Radioman’s Separate Mission:
While the ship was transiting in or near the Japanese Inland Sea and adjoining coastal waters, the radioman, in the privacy of his locked cabin, would connect his receiver to the transmission line that was connected to the antenna on the weather deck. The radiomen would then intercept the Japanese Imperial Fleet radio transmissions. The actual intercept was penciled on paper in KATA-KANA characters and then later the characters were transposed into their Roman letter equivalents. Because of the covert nature of the mission, the RIP-5 (A) was not authorized for these missions. Upon completion of each voyage, the communication intercepts along with an analytic summary were sent direct to OP-20-GX via registered mail.
OP-20-G personnel assigned to the mission:
- CRM Martin Vandenberg, OTRG Class #1, 1929 – deployed five times on SS PRESIDENT JACSON
- RM1C John Cook, OTRG Class #4, 1930 – deployed six times on SS PRESIDENT JEFFERSON
- RM1C Antone Novak, OTRG Class #4, 1930 – deployed five times on SS PRESIDENT GRANT
- RM1C James Pearson, OTRG Class #4, 1930 – deployed four times on SS PRESIDENT CLEVELAND and twice on SS PRESIDENT MCKINLEY
In addition to Seattle, WA and Manila, Philippines (outbound and inbound) ports of call, the itinerary included ports of call at Yokohama, Kobe, Nagasaki, Nagoya, Shimido in Japan and Shanghai and Hong Kong in China. A round trip averaged 44 days with an additional two weeks layover in Seattle. There were 22 missions during this one year period of time.
The intercept receiver was manufactured by RCA for Navy Department (BUSHIPS). It was band-switched to accommodate the frequency span between 80 – 480 KHz. Frequency calibration according to dial setting was imprinted on the panel plate. It was a reliable receiver, but physically hard to handle due to the size and weight (pre-transistor days). During nonoperational times, it was kept hidden under the radioman’s cabin bunk
The Seattle Layover:
During the layover, normal accommodations aboard ship were suspended requiring the radiomen and the aerographer to look for affordable living quarters in the local area. Normally they would find an available room at the YMCA. First order of business was to touch base with Staff HQ 13th Navy District to pick up paycheck and mail. These visits provided the staff with an opportunity to verify the “alive and well” existence of each traveler.
According to NCVA, five Marines, William Kiser, Paul KIugler, William Thomson, Ogden Wilson, and Winnett Robinson were trained in Kata Kana at the Navy Intercept Station in Shanghai, China in 1927. On September 20, 1927, these five new intercept operators departed Shanghai en route to Peiping. In October of 1927, CRM Dorman Chauncey arrived in Peiping and under his leadership the station was established.
In September 1928, William Kiser and Winnett Robinson were assigned “spec temp det d” on the USS Memphis CL-13. CRM Chauncey, Paul Kugler and Ogden Wilson were assigned to the USS Trenton CL-11. They remained on board for most of September. It is believed these men were the first deployers to intercept communications.
(A) Register of Intelligence Publication, fifth in the series, a typewriter that was secretly developed by the Underwood Typewriter Company to convert the unique radiotelegraphy of the Imperial Japanese Navy into Roman alphabet equivalents.
James Warren Pearson, LT USN (RET)
John “Gus” Gustafson, CTRCM USN (RET)