From Cyanide to the North Pole – a Tale of WW2 HF Operation, by Historian
As partial preparation for my upcoming HF NVIS class, I’ve been re-reading two books, as well researching online, regarding an extraordinary but little known operation that occurred in occupied Holland during World War 2. These two books are “Between Silk and Cyanide” by the former code chief of the British Special Operations Executive (SOE,) Leo Marks, and “London calling North Pole” by the former head of German military counterintelligence in Holland, Herman Giskes.
This extraordinary operation was known by the Germans as Operation North Pole, and a quick summary is that starting in the spring and summer of 1941, the German Military Counter-Intelligence organization (Abwehr), through their signal intelligence group, were able to detect, locate by means of radio direction finding, and prevent further operation of, the two allied radio operators that the British SOE had active in Holland at that time. During the rest of 1941 and into 1942, the Abwehr penetrated the struggling Dutch Resistance, and in March 1942 arrested and turned an SOE radio operator named Lauwers.
The Abwehr, ably led by Herr Giskes, took possession of Lauwer’s radio together with his frequency crystals and his codes. First operated by Lauwers and later by skilled German operators, the Abwehr “played back” this radio station. For the next two years the Abwehr intercepted over 50 British agents and tons of arms, ammunition and explosives intended for the Dutch Resistance. Most of these agents, including new operators, were eventually executed. The Abwehr put the captured British equipment and codes to use and put those stations on the air as well. The Abwehr was telling the SOE where to drop British agents and material, and had thoroughly penetrated the SOE operation in Holland.
Meanwhile, as Operation North Pole was getting underway to the delight of the Abwehr, and the eventual dismay of the British, Leo Marks, first rejected by Bletchley Park as a code breaker began his service with SOE at the age of 20 as a code maker for the SOE. It was Marks who raised suspicions about the transmissions coming from Holland, and it was largely his initiative that enabled SOE to first detect the German counterintelligence “playback” of their captured stations.
Marks’ memoir covers the period from the start of Operation North Pole to the end of World War 2. His memoir reviews in detail a host of information on what errors were made by the British SOE during the war. It also appears that Marks is responsible for developing a variant on the Brevity Matrix now SOP in military and irregular radio communication.
So, what frequencies did the SOE use? Giskes mentions specific frequencies very rarely; the two mentions I saw were on page 17: 6677 kHz and 7787 kHz. This agrees with my online reasearch; the SOE in Europe was using transceivers ranging from 2 mHz to perhaps 10mHz; one SOE set went as high as 16 mHz, for use in central Europe and other distant locales.
What this means is that the British SOE operating in Western Europe was using HF Near Vertical Incidence Skywave- NVIS. It’s about 200 miles from Rotterdam to London, a perfect distance for NVIS. The Germans were challenged to get a location of a clandestine transmitter if the SOE, as they did later in the war, changed callsigns, locations, and frequencies, even when transmissions were as much as 9 minutes long. (In fairness, crystals were hard to come by early in the war and early model transceivers were heavy and bulky.) Once an approximate location was had, the Abwehr put their superb local radio direction finding equipment to use and located the precise block from which transmissions were coming, and after that, things got ugly for the operator. Most of the agents captured during operation North Pole were executed. Otto Von Bismark is famously quoted as saying- “Fools you are who say you like to learn from your mistakes. I prefer to learn from the mistakes of others, and avoid the cost of my own.” If you want to learn how to avoid the mistakes the SOE made, and enhance your HF skills, come to class!
For further information, see the following links:
https://www.cryptomuseum.com/spy/b2/
http://messui.polygonal-moogle.com/valves/SC199809.pdf
https://messui.polygonal-moogle.com/valves/SC199809.pdf
https://www.tracesofwar.com/articles/4706/England-game.htm
https://brushbeater.store/products/hf-nvis-operations-course-28-30-mar-mo
With regard to all who seek the Light,
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About the Author: Patriotman
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GUNS N GEAR
A good description with statistics, drawings, etc., of the Nazis’ methods of hunting transmitters is found in the book Clandestine Operations: The Arms and Techniques of the Resistance, 1941-1944 by Pierre Lorain. I would use that section when I used to teach this. The principles haven’t changed, just improved technology and magnitudes faster results. Like many things in the tradecraft arena, the solution to this is low-tech. First understand the problem (avoid getting caught.) Then understand what the adversary uses to detect your transmissions. Then figure out what the adversary’s limitations are. Then develop counter-methods using cheap and available parts/equipment and corresponding TTPs for what you’ve built. Enough knowledge and the ability to think outside-the-box translates into readily available and inexpensive solutions (i.e., portable and disposable equipment – hint-hint.)
Great article, Historian.
As somewhat of a sequel, it may interest you to look at the Australian SOE counterpart in the Pacific, the Services Reconnaissance Department (SRD), Operation Lagarto mission into Japanese-occupied Portuguese Timor, where signallers were captured by the Japanese and then forced to operate their B2 sets as if still free, resulting in the loss of subsequent parties who parachuted straight into an ambush or captivity.
The captured signallers were using their standard duress codes to signify their status as prisoners of the Japanese, but a variety of factors meant that the signals center in Darwin and SRD headquarters in Melbourne ignored the duress signals and continued as normal.
Following the “North Pole” debacle in Holland, one of the SOE Staff involved, a Major Bingham, was exiled to Australia where it was thought he could not do any further damage.
Bingham, then in charge of Allied Intelligence Bureau facilities in Darwin in Australia’s north, also had full knowledge of and indeed oversaw critical aspects of the Operation Lagarto debacle in Timor leading some to suspect that he may have been a German asset all along. The only evidence I have ever found for that is circumstantial and hearsay from veterans, but it’s an intriguing thought.
Cheers,
13-1A