Last time around we looked at Radio Monitoring during WWII from the British side of things. This time we will look at some of the contributions made by America, which were by no means insignificant!
Benson House and Chopmist Hill
In the United States communication gathering during the war was intense and secretive, just as in the United Kingdom. Two sites whose roles only came to light long after their war-time use was Benson House in New York and Chopmist Hill in Rhode Island.
On a plaque honoring the work done at Benson House, it states:
From January 1942 to June 1945 FBI agents and radio technicians secretly living and working at Benson house broadcasted radio messages to the Germans in Hamburg who believed they were communicating with their espionage agents in the United States.
Working closely with military deception planners, the FBI send hundreds of accurate and fictitious reports designed to confuse and mislead the Nazi leadership regarding allied military plans and intentions. Among Benson House’s most significant World War II contributions was the receipt of a German message in April 1942 instructing its spies to obtain information about American atomic bomb development; an order that helped influence President Franklin D Roosevelt’s decision to pursue an atomic weapon. Messages transmitted from Benson House helped deceive the German High Command about the timing and location of the June 6, 1944 Allied invasion at Normandy while others mislead Japanese forces about U.S. advances in the Pacific Theater of operations.
Using German double-agents the FBI was able to convince the Nazis that they were getting information from their spies about the Allied forces and plans. This was known as Operation Ostrich, which was part of a larger Allied program called Operation Bodyguard.
The British had begun something called the Double Cross System to send misinformation, and the FBI adopted this program after the attack on Pearl Harbor. MI5 placed an assortment of genuine and imaginary double agents, each with distinct backgrounds and personalities, near important military sites throughout England, Scotland and Wales.
They then transmitted phony intelligence reports about everything from shipping figures, troop configurations and movements to wartime alliance issues. The intercepted communiqués designated Ultra enabled MI5 to track the flow of these messages through the German communications system. This in turn allowed them to assess how such information was being accepted or rejected. Benson house and Chopmist Hill made good use of this technique, and in no small way shortened the war significantly, as well as saving thousands of lives.
According to Dr. Raymond Batvinis, a retired FBI agent and FBI historian, “A cover story was developed that Johnson [supposed owner of Benson House] suffered from tuberculosis and was, therefore, deferred from military service. The house was outfitted by FBI technicians with several large shortwave radios and supporting equipment. Antennas were hidden in nearby trees and intruders were discouraged by Clifford, the agent’s large German shepherd.”
The radio equipment drew enormous amounts of electricity according to Batvinis, and not wanting to attract undue attention from the local utility companies, the agents powered their equipment using the engine from a Buick which they bolted to the basement floor.
At Chopmist Hill in Rhode Island, similar work was being done by the intelligence division of the FCC, particularly with regard to monitoring German communications, right down to tank-to-tank communications taking place in North Africa. Very little of this work was known to the general public until recently, but the success of the installation was incredible. It was part of a series of 13 listening posts across the country, but its location seemed to have just the right mix of altitude and propagation.
One of the most significant services provided by the Chopmist Hill listening post was the ability to pinpoint signals within minutes almost anywhere. This was due in no small part to the miles of antenna wire stretched across the property. According to Tom Mooney, a Providence Journal reporter, a 40-member team of FCC agents worked at the station monitoring over 400 known transmission sites, including capturing signals meant to be disguised by stronger commercial broadcasts. His excellent article may be found here.
In a report only recently declassified by the CIA there were a number of listening stations and direction-finding efforts used in South America to monitor and locate German communications during WWII which may be found in a report here.
Acoustic Listening Stations
“Denge acoustic mirrors – March2005” by Paul Russon
While not directly on topic, I have always been fascinated by some of the acoustic listening stations which were set up along the southern coast of England to listen for approaching aircraft before the invention of radar. These parabolic receivers were designed to be monitored as an early warning device, but experimentation stopped when chain radar was developed. From the image below it can be seen that different shapes were being tested, and the construction of such concrete reflectors must have been quite challenging.
While never actually put into service, one of their most significant contributions to future radar use was the idea of using interconnected stations to pinpoint the location of an enemy. This greatly helped the effective use of radar in WWII.
Modern Relevance
The modern relevance of the WWII-era monitoring to me is the recognition of the fact there is still a place for such monitoring since radio-to-radio communication is still one of the most effective means of getting information across great distances with little or no interference.
We as radio enthusiasts and civilians have the opportunity to monitor the airwaves just as was done by thousands of volunteers around the world during WWII. Do I believe I will capture some significant clandestine transmission which might thwart an attack against my country? No, at least I deem it highly unlikely. I do however believe there is nothing wrong with being aware of the possibility, and even just having the concept/possibility back in the recesses of my brain may alert me to a potential situation I might otherwise dismiss.
With the proliferation of digital modes, the ability to capture and decrypt said modes, and the ability to record large portions of spectrum at any given time, who knows what we might find?! There are certainly groups both official and unofficial who monitor frequencies, and even a casual scan of the HF bands at various times will likely land one on a “numbers” transmission from Cuba or Russia. These are repeated sets of numbers given verbally as well as digitally, which are likely coded messages to operatives around the globe.
Humans being human means some of the same mistakes made by the German operators which allowed for the breaking of both Enigma and Lorenz ciphers could one day allow for the breaking of the numbers code. After 9/11 there was certainly a push to involve civilians with language skills to monitor communications of all kinds for possible future attacks, and any heightened state of awareness for any kind of attack could produce radio traffic which could prove invaluable if intercepted.
While I am hardly a conspiratorialist in any sense of the word, I do believe some of the old tried-and-true methods of information gathering warrants attention. As radio enthusiasts with sophisticated hardware and software at our disposal, we could be at the forefront of civilian participation should the need arise.
I think of those radio hobbyists experimenting with LF communications, seemingly such a small niche of operators, but their experimentation has provided us with a much better understanding of what is capable on LF ranges, which might someday come in handy during emergency situations.
Technological advancements are always a two-way street: what can be a benefit for us is also something which can be used against us. This might be one of the best reasons to keep as current as possible with all advances on the radio front. A well-equipped station might just allow us to hear that unusual flutter and whine of a covert digital signal which our software can decode—how exciting would that be! Perhaps such monitoring is all just good fun in these times, but who knows? I for one plan on keeping at least an occasional ear on the ground to listen for approaching hoof beats!
73, Robert AK3Q
Originally published in the June 2017 issue of the Q-Fiver.