Standing Well Back
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Tremble! – The Answer to the Mystery Device

A couple of weeks ago I set blog readers a challenge regarding this device, who made it, what the mystery component in the bottom right corner was, and who rendered it safe.

Well done to KH for his (close, but not perfect) answer. I’ll be buying him lunch soon.  It’s actually a pretty interesting story.  The device was found placed next to a telephone junction box under a manhole cover in a street in Arthur Square, Belfast, Northern Ireland, laid by the IRA , in 1922.  The fuel can “Pratts Perfection Spirit” contained a home made mix and two improvised igniters (not a detonators) in parallel. The EOD team (about more of which shortly) recovered a wooden box with a single slider switch on the outside. Inside was the timing circuit, which had failed. There was a 4 volt “Ever-Ready” battery, an American made clock with a soldered wire switch connection.  The improvised igniter design is quite intricate with a thin copper wire running through magnesium flash powder held in a glass tube, but with a spark gap. The can contained about 20lbs of home made incendiary mix, based on sodium chlorate, some scrap metal and  handful of bullets.  When testing the explosive, it burnt with an intense heat, but interestingly also proved in some circumstances to be “detonable”. I’m leaving out details of the mix for obvious reasons.

Here’s a circuit diagram , done in follow up investigation and analysis.

(This device did not work)

The mystery component is, I think, very interesting, but received scant attention at the time. It is described as a “trembler” but it would be wrong to think of it as an anti-handling trembler switch.  It is in fact an induction coil device for upping the voltage from the 4v Ever-Ready to sufficient voltage to cause the igniters to act as designed. It is actually a car component from a Ford Model T.  This component was known as a “trembler” or “buzzer coil”, and provided sufficient voltage for a car’s ignition system (several thousand volts).  Here’s a video explaining this component.

These trembler switches were popular with ham radio enthusiasts and early electronics hobbyists as an easily available and reliable component.

Finally we come to who rendered it safe. For many recent decades, the lead military agency for EOD in Northern ireland was the Royal Army Ordnance Corps who morphed in the 1990s to the Royal Logistic Corps. And very proud of it we were too!  But in the 1920s, it was the Royal Engineers who provided their expertise to deal with the device and many others.  I can hear my spiritual foundations shaking…

Other devices dealt by the Sappers near Armagh that year were cast into concrete to look like kerb-stones, a technique used more recently in Iraq. They were initiated by command-wire.

Update: Render Safe Procedure used in 1922

I have been asked about the Render Safe Procedure (RSP) used by the Royal Engineer EOD personnel  on this device in 1922. I don’t often discuss these things for obvious reasons but I think I’m OK with this one and its quite interesting.  Here’s what they did:

  1. Filled the manhole with water from a fire hose, submerging the device. Gave it a three hour “soak”.
  2. Removed the wooden box (which was in a sack) from the manhole, cut open the sack. There was a concern over a possible booby trap switch attached to the sacking but none was
  3. The external slider switch was cut off manually, leaving an open circuit
  4. The wooden box was pried open, and components separated after photographing
  5. The cap of the fuel can was removed manually  and the “sand like” HME observed, with the leads leading in.
  6. There was a small 1″ diameter hole in the base of the can covered with some sort of cover.  Apparently this concerned the operator as it may have indicated something clever included in the devices construction. Rather than pull the leads out through the cap, or open the tin with a tin opener or hammer and chisel, the explosive was carefully removed, through the bottom 1″ hole, bit by bit with a a long gouge to eventually reveal the igniters (at this stage assumed to be detonators/blasting caps). These were then cut out.
  7. A series of tests were conducted on the components, quite thoroughly.

 

20th Century

IED Innovation… or not

In May 1992 I was just starting my second tour in the EOD world. One of my jobs was to disseminate to my colleagues information on technically significant IED incidents, and the following was one of those incidents, and seemed very innovative. Given the ongoing discussion about “Backstop Borders”, or not, with the Irish Republic, it’s also quite pertinent.

In 1 May 1992, the British Army manned and ran a checkpoint ay Cloghoge on the Northern Ireland/Irish Republic border adjacent to the main road between Dublin and Belfast. This is about as far South as South Armagh goes, and in those days there was a very high level of threat from the Provisional IRA.  The main railway line also sat right there, and the small post, quite heavily protected, was right next to the road and the railway. It was normally manned, if I recall correctly, by about a dozen soldiers, providing “cover” and assistance for the police stopping the cross-border traffic at the check point. In Army terms the checkpoint was called “Romeo 1-5” (R15).

The Provisional IRA mounted a clever attack on the checkpoint. They stole a mechanical digger, and separately, a van. They loaded approximately 1000kg of home-made explosives in the van. Using the digger they made a makeshift ramp from the road, up to the railway lines, manoeuvred the van up the ramp then fitted the van with railway wheels. The digger was then used to lift the van, with its railways wheels, onto the the railway line (it wasn’t that busy a line and it was the middle of the night). All this happened out of sight of the checkpoint, at about 800m south of the border.

The van was fitted with a spool of cable, to initiate the device, and the cable fed to a terrorist who could see the checkpoint or someone who was in radio contact of someone who could see the target. At about 2 o’clock in the morning the van was set off in first gear, with no driver, towards the checkpoint paying out the spool of cable.

The Army sentry on the checkpoint, Fusilier Grundy, heard and then saw the approaching vehicle bomb and raised the alarm. Most of the occupants of the checkpoint took cover. Fusilier Grundy, correctly assuming this was a threat to his life and those of his team, opened fire in an attempt to disable the vehicle bomb. at 0205hrs the device was exploded next to the concrete sanger containing Grundy, killing him and throwing the ten ton protective sanger into the air. The remaining soldiers survived in a shelter, built to protect them if a vehicle bomb was delivered by road.  The replacement to this checkpoint was removed when the Good Friday Agreement came into effect.

I duly wrote up a technical report to the teams I supported (I was on mainland UK at the time), and highlighted that this innovative technique had never been used before.

Or so I thought…  But this is “Standingwellback” ain’t it, where I delve back in history. So check this out:

On 31 October 1943 the Germans were holding and guarding a railway bridge on the Ubort River in the Ukraine, West of Kiev. A Soviet partisan group led by an NKVD Major called Grabchak decided to use an “innovative” method to attack the strongly defended, strategic bridge. The area around the bridge was heavily mined, enclosed with barbed wire, there were several machine gun posts and a large garrison protecting it with mortars and other heavy weapons.

Twice a week the local German commandant travelled down the line to inspect the defences at the bridge from his base a few miles away. He invariably travelled to the bridge by a “special section car”, a small vehicle that was mounted on the railway line rails and used by railway officials for inspecting the line. As far as I can work out this was pretty much a road car fitted with railway wheels. Grabchack and his partsians, over a two week period, made a “replica” section car. The base of the vehicle was fitted with five large aircraft bombs. The fuzing arrangement was simple and ingenious. They knew the height of the cross bracings on the bridge. They fastened a long pole, upright between the bombs. Towards the base of the pole was a pivot point and at the base, a length of wire leading to the pin of a grenade fuze connected to the main charge explosively. So the concept was that the “section car” would be sent down the railway, and as it started to cross the bridge, the pole would hit the cross braces of the bridge, pulling the pin from the grenade fuze.   To add to the effect of the “expected” section car, two dummies were made, dressed in German uniforms, one an officer, the other a driver, and sat as realistically as possible in the car.

At 4pm, on 31 October 1943 the car was carefully placed on the rails about 1km from the bridge, just out of sight, near the village of Tepenitsa. It trundled down the line towards the bridge, and seeing it coming a guard opened a barrier and let it enter onto the actual bridge itself, presumably saluting smartly as it passed by. There, the device exploded, damaging the bridge severely.  Interestingly the German forces put out some propaganda that the device was a suicide bomb, driven all the way to the bridge on rails from Moscow, by “fanatical red kamikazes”. Apparently several more of these railway delivered IEDs were constructed and used but I can find no records, which given it was 1943 and the middle of a war full of sabotage operations is not surprising.

I have written a previous piece about trains loaded with explosives in Mexico in 1912, “loco-locos”, here.

So, the analysis of these incidents suggests the following:

1. There are several instances, historically, of trains or vehicles on train lines being the delivery method of getting explosives to targets. A variety of switching methods is possible. The technique can cause significant surprise, and such vehicles can carry sufficient explosives to overwhelm hardened targets.
2. Apparent innovation isn’t always new. Especially on standingwellback.
3. Border crossings are tricky, whichever way you look at it.

1910-1920

This man made IEDs that blew up dozens of British trains

Thanks to “JB” for flagging up an interesting report of an ordnance officer dealing with a German IED in East Africa using “hook and Line” techniques during WW1. It’s led me down a fascinating burrow, and ties up a whole series of IED attacks on trains and other targets. It also provides a dreadful familiarity – an IED campaign with direct parallels to modern IED attacks in Iraq and Afghanistan, and it sits in the context of a part of WW1 that I was barely familiar with. Here’s the story followed by the links and its context in IED history.

This man is Nis Kock. He was a young sailor in the German Navy. He made literally hundreds and probably thousands of IEDs for the the German East African Campaign in WW1.  He is often described as a Danish sailor, but he certainly saw himself as German, although he could speak Danish as well as German.  He was already a member of the German Navy in 1914 when he was recruited for special duties.  The Germans were putting together a blockade runner, a ship disguised as a Danish freighter to slip through the British blockade in the North Sea and resupply the cruiser Königsberg off the East African coast. As a young adventurous man, he jumped at the chance.  His ship, a captured British steamer the “Rubens“, was called the “Kronborg” for the purposes of the mission, loaded with coal, dynamite, field guns and ammunition. It slipped through the blockade in late February 1915, sailed the Atlantic and round to the Indian Ocean coast of East Africa. There the Königsberg was being blocked by British cruisers in the Rufiji delta. At the time there was also a land campaign beginning between the British and the German Forces in East Africa under the command of General Lettow-Vorbeck – a remarkable character. I dont have space to describe this campaign but suffice to say that a few thousand German forces tied up a quarter of million British Empire troops for the duration of the war, who might otherwise have been deployed to the Western Front.  It was a nasty, vicious campaign fought in appalling conditions in the jungle and the bush. What is little known, I think, is the key role that IEDs played in restricting British movement in the theatre. Certainly the use of explosive devices or mines is barely mentioned in British history but it is clear they were fundamental to Lettow-Vorbeck’s successful strategy, operations and tactics.

When the Kronborg arrived off the coast of East Africa it raised the suspicions of the British Royal Navy, spotting it as it tried to break through their screening blockade, and chased it into the shallow water of Manza Bay (nowadays in Northern Tanzania). The ship was damaged by naval gunfire, and scuttled with just her superstructure remaining above water while the crew escaped ashore. Importantly the cargo received little damage and the British didn’t realise this. Over subsequent weeks, Nis Kock and his fellow crew members recovered most of the cargo from the semi-submersed Kronborg, and much of this material became Kock’s raw materials for IED manufacture in subsequent months and years.

What happened next is interesting. The Kronberg’s pseudo-Danish crew (actually German) were co-opted into the German East African Force. Nis Kock, clearly a bright individual was made assistant to the “munitions director”. His task was to store the explosives and munitions and prepare them for use. Keen readers of this blog will recall the following earlier posts:

  1. The use of firearm mechanisms for explosive device initiation.
  2. How trigger mechanisms were used by the Boers in the Boer War to initiate explosive devices atacking British trains

Now it appears that there were a number of Boers, veterans of the war against the British in South Africa a decade and a half earlier. They clearly remembered the technique of using an upturned trigger mechanism as a switch to initiate the explosives in a device. Kock was instructed to manufacture such devices and he got to work.

Here’s a reminder of the Boer device:

It would appear from Kock’s diaries that he perhaps wasn’t aware of the origins of this concept, but he certainly churned them out as packages for the raiding German insurgency to deploy, probably in their hundreds.  It’s clear to me that they were key and central to Lettow-Vorbeck’s plans as Kock received constant requests to produce more.  He was operating either from makeshift workshops or “in the field’ and developed, I think, remarkable skills.  The impact of the IEDs made by Kock was considerable, for example in the summer of 1915, Lettow Vorbeck turned his attention to the Ugandan railway – which ran through what is now Kenya and was a key logistical route for the British. The German insurgency (and that’s what it absolutely was) had considerable success with their IEDs. For example in one short period between March and May 1915, the German insurgents using IEDs blew up 32 British trains, nine bridges and a dam. I believe that these could have all been devices made by Nis Kock.

Kock himself occasionally laid his improvised mines. His experience indicated to him that setting the device was somewhat tricky with the bomb-layer having to reach into the buried device to release the safety catch on the device once it was in position and he describes in his diaries that as a consequence he developed a new design that made the process safer and easier. Regrettably there are no details of this design change.

Kock used a variety of components – usually the initiation switches were the trigger mechanisms from damaged firearms, used either as booby traps or as pull switches for demolitions.  I suspect there was a shortage of “detonators/blasting caps” and there were no batteries to use electrical initiation methods so this got around that problem with the damaged firearm firing a bullet into a main charge of dynamite or an adapted shell fuze. But I am guessing a little here, as Kock deliberately is a little vague on detail in his notes. The main charge was either dynamite recovered from the Kronborg, ammunition intended for the Königsberg in terms of naval gun shells or captured munitions.  The devices were used against trains but also as demolition charges and to emplace on tracks used by the British in the bush, placing a wooden board on top of the trigger and lightly covering the board with sand and earth. Here’s a translated excerpt from his diaries:

 

As I researched the context of this insurgency and its use of IEDs I was struck often by the similarity between the activity of Lettow-Vorbeck’s guerrilla groups and more recent insurgent IED campaigns in Iraq and Afghanistan.  Von Lettow-Vorbeck’s remarkable campaign is worthy of closer study in that context.

Most of all, I am intrigued of a very weird parallel.  At the exact time that Kock was enabling Von Lettow-Korbeck’s campaign against the British in East Africa, exploding devices under trains on the Uganda railway initiated with rifle triggers, an idea from the Boer War, then an identical campaign was being waged in Arabia. Here, Lawrence of Arabia’s insurgent campaign against the Ottoman Turks and the Hejaz railway, was being enabled by Garland’s trigger-initiated IEDs, inspired too by the Boer war experience. See here and here. Same device, same war, different campaigns, different sides.

In terms of an EOD response, there appears to be very little detail.  Here’s the diary event which was sent to me which started off this pot.  In his War Diary, Major Guy Routh reports, “having to dissect these German contraptions for blowing up our train engines and although they learnt to put two trucks of stones in front of the engines, the enemy countered that with delay fuzes. It was no fun pulling a wire from behind a wall in case the bombs go off, nor was it a job that could be delegated”.  It should be noticed also that there was a little technological battle ongoing between the IED design and the countermeasures designed to defeat it – again this translates directly to much more recent experience in recent wars. However new we feel these modern IED threats are, they have almost always been seen before, it’s just that history is always forgotten.

Update: Some more detail of the attacks:

Here’s two photos showing that bridges were blown up:

 

 

I have also found a report that the Germans (probably Kock) made improvised command-detonated sea mines for use at the coast, however none functioned as intended. For attacks on tracks against foot patrols and vehicles, it appears that as well as the wooden board method, the trigger mechanisms were adapted to function by trip wire.

My friend Ian Mills, who has investigated the Boer use of these devices in the earlier Boer conflict reminded me that the British used the counter-IED method of pushing two sand or rock loaded carriages ahead of the train as sacrificial elements against Boer IEDs, so the British re-used this technique here. The Germans claim to have developed a mechanism that would “count” the number of wheels that passed over, so circumventing this counter-measure. Regrettably I have no detail of this.

It also appears that the most effective IEDs were actually made from British demolition charges, captured by the Germans at Tanga.

Command IED

Command initiated explosive device from 1582

I’m steadily working my way through more military handbooks from the late 1500s when there appears to have been a lot of revolutionary thought going into military technology and explosive device development in particular. My previous post on a grenade was dated 1578, you may recall that Giambelli’s ship explosive device was 1584, and I’ve written before about a postal device in the city of Pskov in 1581.  I’ve also written before how “gun-locks” were used as initiating devices for explosives over a 250 year period.

On that latter point I’ve just found a gun lock (in this case a wheel-lock) drawn in a manuscript from Germany, dated 1582. The drawing is here and as you can see the design is very clear.

 

The wheel-lock was a progenitor of the flintlock which came in a few years later, in about 1600. In a wheel-lock a spring-loaded wheel spins against some pyrites held in the cock.  Here you can see how the gun lock has been removed from a firearm and fastened to a frame. A string is attached to the trigger, led around a pulley and away to the person initiating the device. When the target presents itself, the person pulls the string, which pulls the trigger. On pulling the trigger a spring mechanism spins the steel wheel against the pyrites held in the cock. This causes sparks which ignites the fuse. The fuse leads to a barrel of gunpowder hidden nearby.  In a post a few years ago I have an image showing a multiple IED attacks against a military convoy employing these exact devices, so it’s good to corroborate the attack with a contemporary IED design.

So, this is another example of how explosive device design appears to have developed rapidly at this peculiar point in history, across Europe. I think it is the publication of these handbooks and manuals of military science that seems to be helping – bu I’m afraid I’m not a good enough historian to identify other causes of this bubble of ideas. Comments from proper historians welcome!

A couple of follow-up thoughts:

1. The “pull string” could of course be adapted to a trip string, turning the command-initiated device into a victim-operated booby trap.

2. One possibility of the sudden uptick in apparent use of explosive devices at this point in history is manufacturing technology.  I wonder of clock-making saw similar technological leaps at this time.  Wheel-locks were invented in the early part of the century but are quite complex in design from an engineering and manufacturing perspective. Perhaps clock making manufacture and design took parallel leaps at this time and the transfer of ideas to wheel locks (essentially a clockwork mechanism, with a wheel powered by a spring) enabled cheaper device components and they became more commonly available rather than the early wheel locks which were the weapons of the rich.  I’ve just read that coiled carbon steel spring (essential for wheel locks) was first made possible in the early 1500s – perhaps manufacture became easier in the 1570s, allowing them to be more easily and cheaply manufactured, and hence available for regular soldier’s weapons and “one-time use” in explosive devices. Perhaps the wheel lock mechanisms, like in the diagram above, were separated from the main charge and were thus in theory recoverable after the event.

20th Century

Russian WW2 Radio Controlled Explosive Device

I’m afraid this is going to be a long and detailed post, but it is one of the most interesting historical explosive devices I have ever written about.  Despite the length, I must urge a little caution. I’m working from a very small number of poorly translated documents, about a technology that is at the edge of my understanding, and about which there are conflicting assessments and denials. I have some Russian references but my Russian is very poor and worse now through lack of use. Very happy for input from anyone who has a better handle on this or who sees errors in my analysis.

In the 1920’s and 1930’s the Russians developed a number of radio-controlled systems. As an aside, this included radio-controlled tanks.  Another system, and the subject of this blog piece, was the F-10 radio-controlled mine. This mine was first developed in 1929 (90 years ago!) and deployed operationally in 1941 in the “Great Patriotic War” (WW2) against the Germans, most notably in Kiev, Kharkov and Odessa, and against the Finns in what is called the “Continuation War”. Their use came to a real crescendo in September/October 1941.  There are several very interesting aspects to the device, – its design, its employment/and the MO of its use, the highly ambitious planning and significant operations it enabled, and the reprisals that resulted.  Furthermore, the electronic countermeasures employed by both the Finns and the Germans at great speed following technical exploitation of captured systems provide useful historical vignettes about rapid fielding of EW against radio controlled explosive devices.

By necessity, I have to get a little technical, and to repeat, some of my technical assessments and understanding might be wrong, but I’d like to get this out there rather than spend a year refining peculiar technological aspects.

So firstly, the design of the system.  Here’s an image of the main receiver (Rx) of the system. I think this image is actually German, following a render-safe procedure:

The receiver is a briefcase sized radio and decoder, and I’ll come on to the detail of that shortly. It is accompanied by, and wired to, a large battery. More pictures of the components (I think).

The radio component is the Left hand box, the right hand box is the power source or battery. The “decoder” is the small object to the front left.

Below there is a battery, a radio box, and the rubber bag in which the device is placed when concealed (usually buried) and what appears to be detonation cord or cables, perhaps leading to a large explosive charge.

Here’s an image of the batteries and radio enclosed in the rubber protective bag , ready for burial and concealment.

The system is designed to recieve a coded signal , and detonate up to three explosive circuits. The complete device, less explosives, weighs 35kg. There is a 30m antenna, which according to the references can receive a signal if the antenna, placed horizontally, is buried in the ground up to 120cm (some assessments say less),  in water of a depth up to 50cm or hidden by brickwork up to 6cm – Grateful for comments on this aspect from any EW experts or RF engineers.

The system has a complex timing system. Using the batteries alone would give an operational life cycle to the radio receiver and enable power to the explosive circuit of 4 days. But a mechanical timing system is integrated to give a complex range of operations, including a long time delay before activation or providing a number of time “windows”, from as short as 2.5 minutes “on” to 2.5 minutes “off”, and other longer on-off windows, giving a  maximum receiver power life of 40 days.  There is a complex relationship between the length of time windows and the length of the command signal required that I don’t fully understand.  Suffice to say, that several frequency signals in a sequential row need to be transmitted for the decoder to accept a command, and the length of those individual sequential signals isn’t quite clear to me, but is at least a minute and sometimes longer.

Additionally, there are some clever extras… It is possible to set a mechanical time delay to explosive initiation (avoiding the Rx) of up to 120 days. If I understand it correctly, this was usually set as a last-resort back-up self-destruct. It is a mechanical clock and some EOD successes were made by detecting the ticking clock. The explosive contents used with F-10 varied from a few tens of Kg to several thousand Kg.

The device also was fitted or could be fitted (I’m not sure) with anti-handling switches. The anti handling switches quoted in the spec are “EHV, CJ-10,CJ-35, CMW-16 and CMW-60” I haven’t investigated these yet but at least one is a pull switch attached to the opening of the rubber bag the system is deployed in.

The range of the command system of course depends on the power of the transmitter. From German exploitation of a captured F-10 device, the frequencies employed reportedly range from “1094.1 khZ to 130khz”. Again I welcome comment from EW specialists.  This implication is that the “setting” of each F-10 mine to specific frequencies was quite flexible and easy but I’m not sure quite how it was done.  Perhaps by replacing individual tuning forks?  I have found one reference, a Finnish technical exploitation report, saying the tuning forks were colour coded, which would be logical. Another report suggests that the radio receivers were marked with a numerical code in roman numerals, which defined the initiation frequencies.  A slightly contradictory early Finnish exploitation report, very interestingly, suggests that two of the frequencies allocated to the F-10 were set to pre-war popular music radio stations from Kharkhov and Minsk, with a specific “calling tune”.  I can’t quite make sense of that, but never mind.

The decoding system predates DTMF of course. A system such as the F-10 needs to be able to discriminate random signals from an actual command signal, so this system uses (I think) a triple tuning fork mechanism, with specific successive frequencies transmitted over a time window. Only when three successive signals of different specific frequencies, each of a sufficient duration, are received will the “AND” logic of the system allow initiation.

Such a capable system allows for a wide range of operational designs, or employment plans.  It is clear that the Russians used these in areas where they ceded territory, so they are “stay-behind” sabotage devices. They are expensive too, compared to other mines and challenging and resource-heavy to deploy effectively. So to justify that, the targets have to be significant. Initiation could be by a separate line-of-sight concealed engineer team using a transmitter quite close, or indeed could be several hundred km away (I think). So the device could be under observation and initiated at the optimum time, or more remotely, without line of sight, perhaps based on intelligence.

In the Finnish campaign, the Finnish military encountered quite a few of these devices as they re-took the city of Viipuri in September 1941 and rendered at least one safe. One such item is on display in a Finnish military museum. As a result, it is alleged, they developed an electronic counter-measure, which was to set up a permanent high power frequency transmission on one of the first two frequencies. This overwhelms the timer element of the decoder and perhaps jams incoming other frequencies from the system with its power. That, sort of, makes logical sense to me but I’d appreciate comment from any ECM experts. I have seperate reports, hard to confirm, that the “jamming signal” was a piece of music transmitted at high power over and over again at a fequency of 715KHz.  In response the Soviets changed the frequency of the F-10 systems. and the Finns responded by putting the same song out, constantly, on every frequency they could, apparently

Here’s an image of a Finnish EOD team and the F-10 recovered safely from a water tower in Vyborg. I’m pretty sure the “wall” they are leaning against is TNT blocks.


The removed radio controlled exploding device, wiring, 2400kg TNT and the Finnish engineers that found and removed the “mine” from Viopuri/Vyborg water tower

On a more practical level, Finnish engineers worked out that the long 30m antenna gave them an opportunity to locate the mine. In any places where they suspected a buried F-10, they dug a small trench 2 ft deep, around it, and if there was a mine hidden there, they invariably encountered the antenna.

As an aside, I understand that the young Finnish Officer (Lauri Sutela) who rendered safe one of these devices in September 1941 in Vyborg rose to be Chief of the Finnish Defence Forces in the 1980s.  There’s always hope then for young EOD officers to make their way in the world…

German EW responses to radio control initiation appear also to have been developed and deployed quickly. They captured an F-10 mine in mid September 1941 and it appears there were countermeasures deployed, apparently by 25 October at the latest. That’s pretty fast for a capture, technical exploitation to deployed countermeasure cycle.

German countermeasures included:

  1. Digging an exploratory trench looking for the antenna as the Finnish engineers did. Quite often Russian prisoners of war were used for this task.
  2. Use of an electrical listening microphone to listen for the mechanical clock component
  3. A responsive jamming capability to transmit, quickly, a powerful “blocking”  signal if any known F-10 frequencies were detected. I don’t think this was automated.
  4. There was another RF method developed, apparently of limited use, which involved transmitting a “disabling” signal, somewhere “between 150 – 700Hz” but I cant quite make out the sense of that. Again advice accepted, gladly.

When the Germans took territory from the Russians, in 1941, eventually the cities of Kharkov, Kiev and Odessa were ceded.

In the run up to Russian withdrawal from these cities, engineer teams in significant number laid a wide range of mines and booby-traps for the advancing Germans. The Russians worked out that quite often Germans would take over large buildings that had been used for Russian military headquarters, and use them for their own headquarters. It appears that although equipped with a wide range and number of relatively cheap mines and booby traps, the expensive radio controlled mines were used in a very focused manner to target senior officers and their staff in headquarter buildings. The Germans moved into large office buildings (as previously used by the withdrawing Russians), presumably because they had the scale, number of rooms and perhaps even telephone lines. So a vacated Russian Army HQ would become a HQ for the advancing Germans. This provided a predictability that the Russian engineers could exploit. Russian engineers became expert at laying “slightly obvious” booby traps which German EOD would render safe and then assume the ground underneath was clear – but actually often there was an F-10 radio controlled mine buried deep and everything including the antenna was much more carefully concealed.

In the captured cities of Kharkov, Kiev, and Odessa, German generals and their Headquarter staff were killed by concealed F-10 devices over a 7 week period in 1941, as follows:

Between 24 and 28 September, numerous F-10 devices were exploded in central Kiev in buildings occupied the prior week by German Army headquarters.  The F-10 devices were allegedly initiated by command from stay-behind hidden engineer units observing the area from an island on the Dneiper river. In particular an explosion on 24 September hit the Rear Headquarters of the Wehrmacht army Group south killing a large number of officers, including the artillery commander of the 29th Wehrmacht Corps. In immediate reprisals the massacre of Babi Yar took place, with a death toll of 100,000.

On 22 October, the Romanian Military Headquarters in Odessa, established 3 days earlier and manned jointly by Nazi and Romanian military staff was exploded up by an F-10 device (I believe) killing 67 people including the Romanian General. 40,000 Jews were killed in reprisals.

On 14 November, multiple buildings just occupied by German forces in Kharkov were destroyed I think with F-10 devices. There were hundreds of casualties, including the German commander, Generalleutnant Georg Braun. In immediate reprisals 200 civilians, mostly Jews, were hung from balconies of surrounding buildings. The following month there were further reprisals and 20,000 Jews were gathered at the Kharkov Tractor Factory. All were shot or gassed in a gas van over the next two months.

It is hard to get to the bottom of how many F-10s were used in these cities but I think they were used in significant numbers, alongside extensive conventional mining and booby trap techniques. I think historians in regarding these cities separately in the Eastern front campaign miss the point that this was a clear strategic effort to deploy these weapons to “cut off the head” of the advancing German armies. The fact that these attacks came at the same time as their use in the Vyborg peninsula against the Finns, cannot be a coincidence and I sense a strategic decision to employ these weapons as the Soviets were being pushed on all fronts.  In the main, use of the F-10 was part of operations under the command of a remarkable explosives engineer, Col Ilya Starinov.  I will be returning to discuss Starinov in future blog posts, suffice, for now, to say he was ultimately responsible for more explosive attacks on trains and railways than any other man that has ever lived (by a long way) and fought in at least 4 wars as a Russian explosives expert. He really was the instigator of Soviet Spetznatz tactics.

This F-10 radio controlled device then poses a fascinating case study of an early radio controlled explosive device threat, and how a technical capability (in this case of a pretty flexible system) when coupled with intelligence and innovative employment can pose significant threats not only to whatever troops are in its path, but also targeted specifically on high value enemy leadership as part of a strategic plan.  The appalling reprisals to these F-10 attacks suggests the concern felt by the Wehrmacht.

This story also demonstrates the rapidity that is possible with suitable technical intelligence resources and processes to develop both technical and procedural countermeasures. The RC threat and response game is nothing new.

 

Update:

I’ve been looking further into how the F-10 radio controlled mine was designed.   In itself it is an interesting story.  In 1923, the Soviets started up a “Special Technical Bureau” for “Military Inventions of a Special Purpose” known as “Ostekhbyuro” in typical Russian fashion.  The two people credited with the invention were V. Bekauri and V Mitkevich. Bekauri, was instrumental in developing a number of other Soviet radio controlled systems including the Teletank and other guided weapons. I believe the work on the F-10 mine was completed in 1929. In 1932 the devices were taken on by a specially constituted military Unit, I think designed to exploit the specific capabilities of these devices. The radio controlled mines were at first referred to as “BEMI” mines, named after the first two letters of the last name of each inventor. Later they were re-designated F-10.

In 1937, Bekauri had risen to be Director of the Ostekhbyuro, but was arrested, interrogated, charged with counter-revolutionary behaviour, found guilty 15 minutes later and then executed as part of Stalin’s purges in 1937.

 

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