The Manchurian Incident

September 18, 1931 was significant in the Peiping station’s history.
Now Cpl Lesko was alone on watch when he observed a tremendous increase in message volume on the Japanese diplomatic circuits – all high priority.  Lesko informed CRM Max C. Gunn (Chauncey’s relief) that, “Something’s happening out there.  They went crazy early this morning, before it was even daylight.”  What had happened was the “Manchurian Incident.”  Following an explosion of an alleged bomb on the tracks of the Japanese operated Southern Manchurian Railway at Liutiaokou near Mukden, elements of the Kwantoung Army seized the city.  Neither the Japanese Foreign Officer nor the Imperial General Staff had knowledge of the “incident” until after it had occurred.  Essentially, the Japanese Government was force to accept the accomplished fact and explain it as best it could to the rest of the world.  Although the Sino-Japanese conflict was localized at the time, it was a prelude to the holocaust of a decade later.

Recognized For Their Work

CDR John W. McClaran pictured here attending the Naval Academe.  He Retired as RADM

For this and other work on the diplomatic net, the achievements of the marines at Peiping were recognized in a number of ways.  CDR J. Walter McClaren, USN OP-20-G, noted that Peiping and Guam were the most valuable stations the Navy had with respect to their assigned targets and it was primarily through Peiping’s efforts that analysis of Japanese diplomatic systems was able to process.  A March 5, 1932 OP-20-G letter to Colonel James C. Breckinridge, USMC, CO Marine Detachment, Peiping, noted “…the excellent work and progressive development of the Intercept Station Peiping for the past for years, and especially during the last six months.”  Some Marine intercept operators were individually commended, as evidenced by the following letter sent to Cpl Knight and Pvt Smith, that was signed by Commandant of the Marine Corps, Ben H. Fuller:

“The Major General Commandant has noted with pleasure the commendation of the Chief of Naval Operations for your excellent communications work, and takes this opportunity to express his appreciation to you and to commend you for your capable and intelligent performance of duty.”

Japanese Communications Procedures Improved

Japanese navy communications changed rapidly from the 1920’s , the evaluation of a typical Japanese naval radio circuit was that operator proficiency varied, especially with respect to speed and caliber of operation; circuit discipline was “ragged” and there were indications radio equipment used by both shore stations and fleet units was very heterogeneous and of generally inferior design and construction.  This was evidenced by a variation in individual ships maintaining assigned frequencies, transmitter malfunctions, and difference in tones of transmission.  However, by the early 1930’s the situation has changed. Japanese Navy communications standards were judged comparable to those of the U.S. Navy.  It was not unusually for Japanese radio operators to transmit manually at 30 groups per minutes for two and three hours without a break or error.  Constant communications drills of increasing complexity were noted.  The Japanese Navy’s signals security posture improved greatly with the introduction of power and frequency management as well as shifting frequencies and callsigns.

Intercept of Japanese First Fleet Maneuvers!!

As stated, Peiping’s primary target was Japanese diplomatic communications, Peiping and the other Far Eastern COMINT stations would shift coverage, dropping all but the most important diplomatic circuits, whenever Japanese naval units conducted annual Combined Fleet maneuvers.  During the 1933 Combined Fleet maneuvers, Peiping’s primary targets were the Tokyo, Sasebo, and Takao, Formosa (now Liausung, Taiwan) Naval District Communications Units’ LF and HF circuits, and the Yokosuka Communications Unit’s LF circuits.  Secondary targets were HF radio circuits of the Homeland Naval Air Force.  Due to poor hearability, Peiping generally could not intercept LF circuits during the afternoon while the Yokosuka LF circuits could not be heard at all.  However, the station experienced moderate success with HF circuits, particular those of the Tokyo Communications Unit.  Despite these problems, Peiping had two notable successes.  It obtained the first intercept of the Combine Fleet flagship, IJMS MUTSU, which was the U.S. Asiatic Fleet’s first indication of the Japanese First Fleet’s commencement of Fleet maneuvers.  The station later identified the classified callsign of the Fourth Fleet’s 3rd Submarine Squadron which provided valuable insight into the Combine Fleet’s classified callsign system.  During the 1934 Combined Fleet maneuvers, Peiping was basically assigned the same targets as the 1933, although some adjustments were made during to the previous year’s lack of success of LF targets.  However, success was minimal due to the turnover of Marine operators during the spring of the year.  The new personnel had no prior experience against Japanese naval communications and were therefore unable efficiently to intercept and copy them.

Move from Peiping Back to Shanghai

On September 28, 1934, CinCAF requested CNO’s authorization to relocate the Peiping intercept side to the 4th Marine Regiment’s Radio Station at Shanghai.  CinCAF cited both security and improved reception as reasons for the proposed move.  The Navy Department approved the request on November 28, and further recommended the Shanghai station be provided with new Bureau of Engineering equipment.  The Peiping station would remain in operation until all Marine Corps intercept operators then on board had transferred from the Asiatic Station at the expiration of their tours of duty.  Since the majority of Peiping Marines were scheduled for transfer by the summer of 1938, the site could be decommissioned at that time.  For security reasons it was considered absolutely essential that the Peiping personnel knew nothing about the Shanghai site.  Capt Shelton C. Zern, USMC, was under order to the Marine Detachment, Peiping.  To satisfy the need for a commissioned OIC at the new Shanghai station, on April 15, CinCAF proposed that Capt Zern’s, orders be modified for assignment to the 4th Marines, Shanghai.  His assignment was to be as the Security Officer but his actual duties were to be the Radio Intelligence Officer.  Capt Zern received training in radio intelligence matters at the Navy Department prior to his departure from the United States, and arrived at Shanghai in May 1935.

By James McIntire and R. D. Howell, Sr. (NCVA)
Edited by Mario Vulcano