SOE Sabotage – Rail Charge

During the Second World War Britain’s Special Operations Executive (SOE) developed a whole series of sabotage devices for use behind enemy lines. Using unique archival footage this series of short videos examines some of the weapons developed for use by SOE agents in occupied Europe. In this episode we look at how rail track could be destroyed by plastic explosive.

Destroying railway infrastructure was a key mission for the Resistance groups and SOE agents active in occupied Europe. Numerous methods of damaging or destroying railways were developed, including Exploding Coal, which we have covered earlier in this series. In this 16mm colour footage, believed to have been filmed in 1940, we get an early look at the methods the SOE were developing to destroy track. The ultimate aim was to derail the locomotive and wreck the train with minimal effort and explosive.

In the footage we see two charges have been placed on the piece of track, with detcord attached to both. A soldier, with what appears to be a lever-action Winchester 94, is then seen taking aim. It seems he’s aiming at a striker board attached to ignite the detcord. He fires, we see a puff of smoke and a second later the charges detonate.

The footage then cuts to several men collecting the debris of the shattered piece of track. The track appears to have two large chunks blown out and the top edge, between the two charges, completely blown off.

An early SOE demonstration with the charges set on the rail (IWM)

Later in the war more testing was done and more refined techniques were developed. In their book SOE: The Scientific Secrets Boyce & Everett note that trials of devices and techniques for destroying railway lines carried out at Longmoor where the British Army had extensive sections of track and samples of rails used in different European countries. Trials to find the right quantity and positioning of explosive charges were carried out in late December 1943, these tests would inform later operations.

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Fog Signal Igniter (SOE’s Descriptive Catalogue of Special Devices and Supplies)

The SOE’s Descriptive Catalogue of Special Devices and Supplies includes a pair of illustrations demonstrating two methods of laying and detonating these charges. A so-called ‘French’ method with a pair of what the catalogue terms ‘Igniters, Fuze, Fog Signal, MkIA’ ahead of the charges in the direction the train was expected from. The train would crush these Fog Signals firing them and igniting a length of detcord linked to a pair of 3/4lb explosive charges fixed to the track as we see in this film.

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Polish Rail Charge layout (SOE’s Descriptive Catalogue of Special Devices and Supplies)

The alternative ‘Polish’ method had the same sized and located explosive charges but placed a Fog Signal either side of the charges to ensure that no matter which direction the train came from the charges would be detonated. This method was used on single track stretches of railway. Both of these methods were rated to ‘remove about one metre of rail.’

In this photo we see a member of the French Resistance setting an explosive charge on a railway line. While likely a posed photo we do see the pair of Fog Signals which will stet the charge off. These photographs show a pair of trains reportedly derailed by explosive charges.

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A derailed French train c.1942 (AIRAN)

Boyce & Everett in their book SOE: The Scientific Secrets suggest that as many as 48,000 ‘Railway charges’, presumable a kit, were produced by the SOE. From the footage we can certainly see this method of destroying rails was effective.


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Bibliography:

World War II Allied Sabotage Devices and Booby Traps, G.L. Rottman (2006)

SOE’s Descriptive Catalogue of Special Devices and Supplies, (1944)

SOE’s Secret Weapons Centre: Station 12, D. Turner (2007)

SOE: The Scientific Secrets, F. Boyce & D. Everett (2009)

Arthur John G. Langley’s Unpublished Memoir (1974)

Footage use is part of the Imperial War Museum’s collection © IWM MGH 4324 & 4325 and is used under the Non-commercial Use agreement.

SOE Sabotage – Magnetic Petrol Tank Bomb

During the Second World War Britain’s Special Operations Executive (SOE) developed a whole series of sabotage devices for use behind enemy lines. Using unique archival footage this series of short videos examines some of the weapons developed for use by SOE agents in occupied Europe. In this episode we look at an explosive magnet bomb, designed to be attached to any magnetic surface and detonate to destroy machinery or vehicles. It later evolved into the small pocket-sized ‘Clam mine’.

Today, we’re lucky enough to have some colour footage showing the of testing of a magnetic bomb which could be attached to the petrol tank of vehicles. The footage comes courtesy of the Imperial War Museum.

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A still from the footage showing the charge placed on the body of the car (Imperial War Museum)

From the film we can see that the bomb consisted of a small block of plastic explosive, a pair of strip magnets (or possible a horseshoe-shaped magnet) and a Switch No.10 time pencil delay detonator. The explosive block itself looks to be slightly smaller than the SOE’s standard 1.5lb charge.

In the film we see the bomb placed on the boot (or trunk) of a saloon car before various civilians and a corporal experiment with various ways of covertly attaching the bomb to the underside of the car. At one point the corporal allows himself to be dragged along behind the vehicle before making his escape.

Luckily the 16mm footage, filmed by Major Cecil Clarke, also shows us the effect of the explosive charge mounted on a petrol tank full of fuel. According to the details listed for the film by the Imperial War Museum the footage was filmed in 1940, at SOE Station XVII, located at Brickendonbury House in Hertfordshire.

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A still from the footage showing the bomb’s magnets (Imperial War Museum)

This configuration of the bomb doesn’t appear in the Special Operations Executive’s Descriptive Catalogue of Special Devices and Supplies published in 1944. However, Colonel Leslie Wood, Station XII’s commanding officer, described the demonstration put on during a visit by Brigadier Robert Laycock of the Commandos and William Donovan, the head of the American OSS in June 1942. One of the scheduled demonstrations was the “Effect of small ‘magnet’ charge of explosive on petrol tank of car.”

It appears that this ad hoc magnet charge evolved into ‘the Clam’, which was a smaller, version of the magnetic Limpet mine. The Clam evolved through a number of marks with the MkI having a stamped sheet metal casing and the later MkIII using a bakelite, plastic casing.  Both were made up of a plastic explosive charge inside a rectangular, rounded case with a pair of magnets at either end. They were detonated by either a Time Pencil or an L Delay fuse attached to a No.27 detonator. The MkIII had 8oz (226g) of high explosive filler, such as TNT/Tetryl 55/45.

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MkIII Clam (Imperial War Museum)

While unlike the larger Limpet they weren’t developed for under water use but the Clam could be mount onto any vaguely flat magnetic surface including engine blocks, fuel tanks, crank cases, cylinder blocks, rail tracks and steel plate.

At just 5.75” x 2.75” x 1.5” they were easily concealable, could be carried in a pocket and were non-descript enough not to draw attention. An estimated 68,000 Clams were made under supervision at Aston House according to Des Turner’s book on Station XII.


If you enjoyed the video and this article please consider supporting our work here. We have some great perks available for Patreon Supporters. You can also support us via one-time donations here.


Thanks David Sampson of www.millsgrenades.co.uk for the use of his photo of the cutaway Clam.

Bibliography:

World War II Allied Sabotage Devices and Booby Traps, G.L. Rottman

Technology and the Civil War, S. Mountjoy & T. McNeese

SOE’s Descriptive Catalogue of Special Devices and Supplies, c.1944

SOE’s Secret Weapons Centre: Station 12, D. Turner

SOE: The Scientific Secrets, F. Boyce & D. Everett

The footage is part of the Imperial War Museum‘s collection © IWM MGH 4325 and is used under the Non-commercial Use agreement.

SOE Sabotage – The Incendiary Case

Following on from our last video & article looking at Explosive Coal, we continue our series looking at some of the sabotage weapons developed by Britain’s SOE during the Second World War.

We’re lucky enough to have some unique colour footage showing the of testing of some of these explosive devices and in this article we will examine an incendiary-filed case.
In this piece of 16mm colour footage, filmed in 1940 by Captain Cecil V. Clarke, we see what appears to be an attaché case containing three medium-sized bottles, which likely contains a mix of petrol and paraffin or some white phosphorus, prepared for testing at the bomb range at Brickendonbury in Hertfordshire, a Special Operations Executive training and research centre codenamed Station XVII. It’s believed that these films may have been produced as teaching aids for the agents trained at Station XVII and this film may have been shown during a lecture.

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A still from the footage showing the case being set up at the test range (IWM)

While incendiary briefcases, attaché cases and even suitcases are listed in the 1944 SOE Descriptive Catalogue of Special Devices and Supplies they were quite different from this case. They were primarily designed for the quick destruction of documents and items carried inside them. They used sheets of potassium nitrate to burn the case’s contents.
The incendiary case seen in this footage on the other hand appears to be designed to be clandestinely placed and detonated with a delay fuse, to set nearby flammable objects on fire. What was described as a ‘Delayed Action Incendiary’.

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The Incendiary Suitcase entry from the SOE’s Descriptive Catalogue of Special Devices and Supplies

In this footage of another separate test we get an idea of the destructive capability of just one of the bottles.

It’s possible that this incendiary case was a proof of concept test for the later cases or perhaps a demonstration of a concealed incendiary device Station XVII were working on. SOE developed a large number of bespoke explosive devices for various missions, so while this device may not have become ‘standard issue’, it may have been developed for a specific purpose.


If you enjoyed the video and this article please consider supporting our work here. We have some great perks available for Patreon Supporters. You can also support us via one-time donations here.


Bibliography:

SOE’s Descriptive Catalogue of Special Devices and Supplies, c.1944

SOE’s Secret Weapons Centre: Station 12, D. Turner

SOE: The Scientific Secrets, F. Boyce & D. Everett

The footage is part of the Imperial War Museum‘s collection © IWM MGH 4325 and is used under the Non-commercial Use agreement.