You can contact me at rogercdavies(atsquiggle)

This blog has evolved into a review of historical and modern explosive devices, and responses to them. Links are drawn between historical activity and similar activity in the world today. Mostly I focus on what are now called IEDs but I have a loose personal definition of that and wilingly stray into discussions of more traditional munitions, the science and technology behind them, tactical employment and EOD responses. Sometimes it's just about interesting people in one form or another. Comment is welcome and encouraged but I do monitor it and reserve the right to delete inappropriate stuff. Guest posts are always welcome. Avoid any stuff that makes the enemy's job easier for them.


Entries in IED Design (35)


Attacking Railway Lines with IEDs using Firearm Initiation Systems

I think I have a final piece of the jigsaw here, that links the IEDs used by Lawrence of Arabia, with IEDs used by Jack Hindon in the Boer War and now, the final piece, with a specific IED designed in the US Civil War.  

My intent here is to show how a specific IED design, improvised from commonly available battlefield materials, that used the weight of a target train on a gun lock trigger mechanism to explode a charge, seems to have begun in 1864, and that design, or very close approximations of it were then seen in the Boer War decades later, and again in WW1 more than ten years after that.  It is of course possible that the design was independently invented - but my supposition is that it was not, and the concept was known by those who deal with explosives in one form or another. The attack mode proved useful in what we would call today "guerilla warfare", often associated with a firearms firing on the resulting shocked and disorientated survivors.

In bringing these together in a historical sequence I am in part repeating earlier blog posts. In uncovering the details I worked backwards but now I'm laying this out in sequential historical sequence, covering a period from the early 1860s to WW1.  I'm specifically looking here at attacks on railways where the weight of the train causes a trigger on a gun "lock" to be initiated - components of firearms were of course used in other sorts of IEDs over many centuries and I have blogged about that here, but that's outside the scope of this post.

1. US Civil War. Union IEDs designed to attack Confederate trains.  As I have blogged before IEDs (then called "torpedoes") were used extensively by both sides in the US Civil War, with perhaps the Confederates making most application of them. After the end of hostilities the Chief Engineer of the US Army, Brigadier General Delafield collated numerous reports on various Torpedos used in the conflict and put them into a historical context, examining the efficacy and appropriateness of use.  I find it intruiging that Delafield, in the decade prior to the US Civil War was one of the US Army's observers in the Crimean War which saw extensive use by the Russians of IEDs.  In the collated reports is a letter written to Brigadier General Delafield by 1st Lieut Charles R Suter, Chief Engineer in the "Department of the South, Hilton Head, South Carolina, on 26 October, 1864. The letter reads as follows:

By direction of Major General Foster, I have this day forwarded by Adams Express, a box containing a railroad torpedo, tools and drawings showing its use.

This torpedo was devised by Charles F Smith, 3d U.S.C.T.

We have not yet been able to try them on the enemy's railroads, but they have been thoroughly tested in experiments. The magazine holds 20 to 30 pounds of powder, and this is sufficient to blow a car off the track besides utterly destroying it. Two magazines can be used with one lock and by regulating the length of the powder train, any car of the passing train may be blown up.  The accompanying tools are simple and light. The idea of the inventor was, to send small parties of men, 3 or 4 in each, with these torpedoes and return. Each magazine is a load for a man. Another man can carry the lock and another the tools.

The manner of laying these torpedoes is as follows: -

The spikes are drawn from three consecutive ties on one side.  A hole is then dug, and the lock placed as indicated in the drawing. The rail is then sprung up and iron wedges placed on the adjacent ties to keep the rail from springing the lock by its own weight. When thus secured, the lock is cocked and capped, and the box closed. The magazine is then buried in the proper place, and the connection made. By using a little care in excavating and carrying off the superfluous earth to some little distance, the existence of the torpedo would never be suspected. The bottom of the arched rail should just touch the lever. Any shock by the bending down the rail pulls the trigger and explodes the torpedo.

In our experiments, a torpedo of 18 pounds was exploded by giving a car sufficient impetus to run over it. The car was entirely destroyed, and rails, ties and fragments of the car were thrown in every direction. One rail was projected 40 feet. 

These torpedoes can probably be used with success in some of the larger armies. Their greatest efficiency lies in destroying the locomotive, which cannot be replaced, whereas a torn up track can easily be relaid.  the magazine should be tarred before being used.

I am, General,

very respectfully,

Your obd't serv't


1st Lieut, U S Engineers & Chief Eng'r D.S.

Here's the accompanying diagram:



The diagram shows a "lock" from a firearm, with a lever engaging the trigger system. This has been "pre-packaged" is a small box with the initiation mechanism causing a fuze to be lit. The fuze is then connected to two containers ("magazines") placed under adjacent sleeper ties.

Despite much research I cannot find a report of a "gun-lock" initiated railway IED in the Franco-Prussian War in 1870, five years after the end of the US Civil War.  But railway IEDs were used, initiated by the weight of a train on the fuze removed from an artillery shell and was the subject of my last blog post here

2. The Boer War.  Gunlock initiated IEDs were used by the Boers against British Trains in the Boer war in 1901.  Here's a diagram of the adapated Martini-Henry gun lock. The similarities of the US Civil war design of 1865 are clear.

Pictures of actual gunlocks from these devices are at this page 

3. WW1 - Lawrence of Arabia and Bimbashi Garland's attacks on Turkish trains in ArabiaLawrence of Arabia's campaign against the Ottoman Turks in the Arabian peninsula in WW1 often attacked the railway lines running south. The IEDs that Lawrence used were pretty much identical to the Boer devices, but had been developed by his ordnance specialist "Bimbashi Garland" and former Ordnance Corps laboratory technician who had been co-opted in the Arab Bureau because of his interest in archaeology.  I have no doubt that Garland was aware of the Boer methodology and simply used the same technique. Details are here

In summary then I think it is clear that the use of a gunlock placed under a railway line to initiate an explosive charge began in 1865, with the invention by Charles Smith, for the Union Army.  This technique somehow found its way to ther Boers in 1901, and then was copied again by Garland and Lawrence of Arabia in 1917. 




Title of this magazine article is interesting...

My old friend Panjandrum saw a military history magazine in a newsagent's today and took this image of Page 35.

Given the title of the article in the magazine, this blog's title, and this piece from this blog in 2012, that's a fine coincidence!  

For what it is worth I'm pretty sure that Garland didn't serve in the Boer War as the magazine articles suggests, but I have no doubt the concept of initiation system came from there. 



The language of IEDs

What we now call Improvised Explosive Devices have had different names over the centuries that they have been used. Here's one you may not have heard of.  The word "caisson" has a range of meanings derived from the "sealed box" of its original meaning. Today a caission is associated with either the ammunition box used in support of an artillery piece, or a sealed box like structure sunk in water to allow engineering work to take place.  But in 1778 "caisson" had this meaning, according to a military dictionary published that year:


Clocks, locks, energy and initiation

I’ve written before about the evolution of gunlocks, from matchlocks, through wheel-locks to snap-huances and then flintlocks because although these initiation systems were designed to initiate firearms they also enabled initiation mechanisms for explosive devices.  This post returns to that subject to discuss a couple of more elements to that story that I find interesting, namely engineering development and some fundamental issues about “energy” chains that apply both to these firearms systems and explosive devices.  In this post I have made some generalisations and simplifications in my description of the technology - forgive me, but otherwise the post turns into a book and neither you or I have time for that.                                                                      
Firearm initiation systems, and in parallel explosive initiation systems, are about initiating a quantity of explosives at a time that the operator chooses.  Thus, in the simplest of all firearm systems, a burning “match” is placed in contact with a small quantity of blackpowder in a “touch-hole” which then initiates a larger amount of blackpowder in the barrel of a gun.   This system worked for hundreds of years in the cannons you see fired in all the movies.                                                                                                                                                
The gun is aimed and the application of the burning “fuse” simply initiates the blackpowder.  The energy in the arm of the man holding the fuse, and the energy in the already burning fuse is enough to initiate the stored chemical energy in the blackpowder in the barrel.                                                                                                                                                                                                                                                               
But in a small firearm there’s an issue of the man pointing the gun and initiating it at the same time. Generally these firearms were pretty large and required two hands to point at a target.  So quite often the firearm was supported with a crutch allowing the firer to point it with one hand, sight the barrel with an eye at a target and use the “spare hand” to place the burning fuse on the touch hole. 
Firing an early firearm without a trigger and serpentine
But let’s face it, that’s a bit fiddly. The touch hole is small and it might be a bit awkward. The firer is concentrating on doing two things, keeping the target in line and finding a small hole with the burning fuse in one hand.   So, with some very simple engineering the matchlock was developed.    All that happened was that a simple S shaped lever was introduced onto the body of the firearm. One end of the lever held the burning fuse in  a specific position, the centre of the “s" shaped piece of metal was a pivot joint and the bottom end of the s was pulled with one finger.  The placement of the s shaped lever (a “serpentine) ensured that the burning match always found the touchhole or the pan at the entrance to the touch hole, and the firer could use two hands to aim the firearm, concentrate on the target and just use a finger to pull the “s" shaped piece of metal.
A very early, simple matchlock arquebus
 Now , manufacturing such a firearm was pretty simple, and within the engineering skills of the average door-lock manufacturer of the 15th century which simply used levers and pivots.   So matchlock firearms were relatively easy to manufacture and relatively cheap. Matchlocks continued to be produced from the 1400s for about 250 years.  I think this is important to understand - although better technology was invented in a series, starting in the early 1500s, match-locks remained a simple and cheap firearm and so were the most common at least until well in to the 1600s.
A nice image of a Japanese matchlock mechanism showing a pan cover
Now, there are some operational weaknesses with the simple matchlocks.  In the simplest of all matchlocks the pan or the entrance to the touchhole  is permanently exposed to the elements. So in poor weather the firearm simply won’t work.  Also the glowing match gives away both the position of the firer and the nature of their weapon.   Both these weaknesses were partially addressed.  Firstly a mechanism of a sliding or levered cover to the Pan or the entrance to the touchhole was developed, requiring some more intricate engineering so when the serpentine was moved then a cover was moved out of the way allowing the match access to the pan.  A bit complex.  Some attempts, too, were made to hide the burning match in a box, but not very effectively. Burning fuse also, by the way, made the weapon unsuitable for those guarding stores of ammunition.  So in the early 1500s the wheel-lock was developed.                                                                                                                    
In large part the wheel-lock invention was enabled by advances in engineering, and specifically advances in engineering from clock making.  On a fundamental level, the wheel-lock utilises, for the first time in a firearm, “potential energy” in a spring.   A wheel-lock, consists of a steel wheel, which has a small chain wrapped around its axle. The wheel is rotated with a spanner, this wraps the chain around the axle and the other end of the chain is attached to a spring.  Thus when the wheel is rotated it induces a potential energy into the spring. The spring is then held by a trigger. A second spring is then set up to hold the serpentine. In this case the serpentine doesn't hold a burning fuse, but a small lump of iron pyrites.  The spring acting on the serpentine holds the pyrites in contact with the rim of the steel wheel which usually has grooves on its circumference and some small notches to encourage friction.  When the main spring holding the chain attached to the wheel is released by pulling the trigger, the steel wheel rotates and, because it is in contact with the iron pyrites, sparks are formed.  The sparks initiate blackpowder in the pan.
So we have the potential energy in the spring, making kinetic energy in the wheel , which initiates chemical energy in contact with the pyrites, which initiates the chemical energy in the blackpowder, which converts to kinetic energy in the projectile, and that kinetic energy is transfered t o the target t cause damage.  A nice little chain, but one which requires a significantly more detailed engineering capability than a match-lock.                                                                                                         
The wheel-lock however has several advantages.   It is safer, in that safety catches can be applied to both the serpentine and the wheel.  The presence of a firearm is not given away by the burning fuse.  It can be prepared well in advance of use (if the springs don’t deform as some where liable to)  The firearm can be concealed. Since it is possible to conceal, the firearm was then made smaller, and so the pistol appeared for the first time, able to be held about a person, and the same person could indeed carry two or three wheel lock pistols. Since this is a blog about explosive devices, then of course the wheel-lock became a potential initiator for IEDs - the device could be hidden and initiated at a point of the firers choosing, perhaps say with a string to the trigger or a potential booby trap switch. IEDs are more suited to initiation by potential energy.
But now we have economics at play. The high level of engineering and therefore cost required for a wheel-lock would make it usually unsuitable for a one-time-use in an IED, although possible.   Only the rich could afford wheel-locks.  So wheel-locks and match-locks existed side by side for decades and indeed for at least 150 years. The economics of the engineering had some other interesting implications.  Matchlocks are simple utilitarian devices usually without decoration through the 16th century. Wheel-locks however, bought by the rich became covered in ornate art, and became models of fine engineering and artistic excellence.  Here’s some images of highly decorative wheel locks.
The fact that wheel-locks were used by the rich also had an effect on the manner in which warfare was conducted.   Ordinary infantrymen could not afford wheel-locks but the aristocratic and rich cavalry could. Cavalry tactics then evolved to make benefit of the capabilities that two or three wheel locks could provide. The cavalry galloped forward to a point within range of their wheel-locks, fired, and galloped back.   The tactics of cavalry using wheel-locks then had an impact on the types of horses and armour being used by the military. The huge horses required for armour encumbered cavalry with lances were replaced with smaller, quicker more agile horses. This perhaps lead, by connection, to the evolution of horse racing and blood stock management.   The armour, designed to to defeat the weapons of the medieval horseman was discarded - armour could be produced to protect against the bullets fired from wheel-locks but frankly it was too heavy.  So the nature of warfare rapidly evolved.  One could say that the nature of warfare evolved over the period of between 1500 and 1620 entirely because of the initiation system moving to a potential energy storage device (a spring) for the initiator rather than a chemical energy storage initiator (the burning match).                                                              
Subsequent evolutions of the gun-lock technology brought together the principle of a potential energy store (from the springs in the wheel-lock), with simpler engineering requirements.   I think that the spring-held serpentine of the wheel-lock got people thinking. Firstly pyrites wasn't always a solid enough material to hold reliably in the jaws of the serpentine, and indeed the spring holding the pyrites wasn’t designed to cause the pyrites to impact with the steel wheel, just hold it against it.  I think that the metallurgy of springs improved throughout out the 16th century.  A powerful spring could cause a flint to strike a steel firmly and reliably enough to set a spark - earlier technology wouldn't allow that - the springs would break or the springs would deform very quickly. But the evolution of clocks and associated engineering developed through the 16th century so that steel suitable for using in springs evolved.  All of a sudden there was a metal available that could be used in a  spring that could force a serpentine holding a flint hard enough to cause sparks. The “snaplock” then developed in about 1540 utilised the same serpentine used in the match-lock and wheel-lock, but this time powered by a strong spring to strike a “steel” to cause sparks - subsequent developments of the snap-huance and then the flintlock were simply improvements on that design, improving its reliability and weather protection.  Essentially then in energy terms, the potential energy inherent in the spring that powered the wheel in the wheel-lock was changed to potential energy in the main-spring of the flintlock. Crucially though the engineering required of the flintlock was still considerably simpler than the technology used in the wheel-lock. Flintlocks could be pretty much mass produced while wheel-locks remained the product of a highly skilled craftsmen. As an aside, the engineering tolerances required of the wheel of the wheel-lock needed to be much tighter than the engineering tolerances in a flintlock. In a wheel-lock the wheel rotates through a slot in the “pan” and if the slot is too big then the gunpowder falls through it.   The fact that flintlocks used potential energy , but were also cheap and able to be mass produced means that they became attractive to use in “one time use” IEDs such as this device . The first mine , Samual Zimmerman's "fladdermine" also use a flintlock mechanism.                                                                                                                                              
It is clear from reading up about the history of clock development that many of the principles of engineering in clocks developed during the period of about 1550 - 1750 were subsequently applied to the production of munitions fuses. There’s probably another blog (or book!) to be written about that. 



18th Century TPU, 19th Century Grave Robbers

I've blogged before about the use of flintlocks and other gun-lock mechanisms used as initiators in IEDs between the end of the 16th century and the middle of the 19th century.   Some recent digging has made me think that the integration of a timing mechanism with a flintlock mechanism was a widely used system, perhaps not regularly within an IED but widely enough that it's use must have been well known, even if only as a potential initiation system.  Here's some images of a couple of peculiar alarm clocks which I think make the point well. The operator sets a time on the clock which when reached released a spring loaded trigger on a flintlock.  A small amount of powder is then initiated which also ignite the wick of a candle which then by a linked spiring stands up in the box. These are I think from the period 1715- 1740 or thereabouts. Nowadays we'd call these a Time and Power Unit (TPU)

 I have also found a "set gun" which attached a flintlock to a tripwire, used as a deterrent for both for both poachers and grave robbers. Here's an image of one of these.  

To be clear I'm not suggesting any of these are IEDs, just that such a mechanism could have been used at the tme to initiate explosive devices.  The set guns were outlawed eventually but in 1878 an inventor, Mr Clover of Columbus, Ohio then came up with a "coffin torpedo" to deter grave robbers who opened a coffin with something like a shotgun cartridge, initiated by the opening lid.  "Torpedo" was the name given to IEDs at that time.   

In 1881 a Mr Howell invented two "Grave Torpedos", much more like IEDs and images from the patent application is shown below. These were much more like an American Civil War land mine, placed on top of a coffin with a plate above it, designed to be initiated when the grave robbers dug down.

These were effective - a grave robber was killed by the device and an accomplice wounded: