Tunnelling Companies of the Royal Engineers

Major Norton Griffiths had already written to the War Office proposing formation of Special Companies of – what he termed – moles. As well as being an officer in the 2nd King Edward’s Horse, a regiment he had personally raised, Norton Griffiths was a Member of Parliament and the head of a large firm of international engineering contractors. In particular his firm employed many men digging tunnels for sewers below major cities in Britain, using a specialist technique known as ‘clay kicking’.

Following a reconnaissance in February 1915, and an interview with Lord Kitchener (Secretary of State for War) Norton Griffiths, armed with almost plenipotentiary powers, was ordered to raise clay kickers and miners for service. The War Office authorized formation of 8 Tunnelling Companies, originally to comprise 6 Officers and 227 Soldiers. Qualified miners were to be paid at an astonishing rate of 7/6 per day (an infantry private received about 1/6). The first 18 Clay Kickers, the nucleus of 170 Tunnelling Coy, were enlisted on Thu 17 Feb 15 in Manchester, processed through the Royal Engineers Depot in Chatham, shipped to France and started work at Hill 60 on Mon the 21st of Feb 1915. This is probably the fastest ever formation from scratch and deployment of a unit to operations.

The build up of the mining companies followed quickly with enlistment of clay kickers, and men from other mining disciplines, and a comb-out of existing units for suitably qualified personnel. Commanding Officers (COs) were initially found from regular Royal Engineers, but most of the remainder were mineral miners from all over the world. By June 1915 the 8th Tunnelling Coy had been formed and deployed, but by then the mine fighting had developed in intensity, and raising and training further companies proceeded. The first Dominion Company in the Field was the Canadian 3rd Tun Coy RCE (raised from Canadian units in France) and deployed in December 1915.

Organization of Tunnelling Companies

Following the initial formation of the Tunnelling Companies their war time establishment was finally settled as follows:-

  • 19 Officers comprising a Major Officer Commanding (OC), a Captain Adjutant, a Medical Officer, 4 Captains each commanding a Section, and 12 subalterns (Lieutenants & 2nd Lieutenants).
  • In each Company there were 4 Mining Sections (around 120 men) capable of operating independently (i.e. they had integral cooks, transport, drivers etc) and there was also a Company HQ section which included rescue specialists, craftsmen, signalers, draughtsmen, Stores personnel etc.
  • Each Mining Section was divided into 4 shifts, each shift generally being commanded by a subaltern or (sometimes) a Sergeant. Full strength was 19 officers and 550 Other Ranks (ORs). Note however that there were some companies designated as ‘Lower Establishment’ which had the same officer structure but only 325 ORs supplemented by 216 permanently attached infantry who were then trained to be ‘Miners Mates’.

Staff

The Tunnelling Companies and operational policy were directed from General Headquarters (GHQ) by a Brigadier-General (Controller of Mines) and a staff which included Geologists and Medical Advisors. Operational Control Control of mining activity was vested in a Lt Col (Controller of Mines), with a small staff, located in each Army HQ (ultimately 5 such). Each Army also maintained a Mine School and Mine Rescue Training organisation.

Accommodation

Tunnelling Companies generally remained working in a sector for many months, and so made themselves comfortable. Rest billets and administrative personnel would be located well back from the lines, usually in villages or towns. Company HQ would be located a mile or two behind the forward line in cellars, caves or dugouts as available. Section HQs usually occupied dugouts in the 2nd or 3rd line. In addition there were dugouts for duty rescue men, central listening stations, explosives stores etc – often within or close to the tunnels.

Rates of Pay

A qualified clay kicker, who enlisted in 1915 as a Sapper (the most junior rank in the Royal Engineers) was paid 6 shillings (30p) per day, which contrasts with about 1s (5p) per day for an infantry private and around 6s per day for a Lieutenant. However non qualified ‘miners mates’ received 1s 2p (6p) per day plus RE supplementary pay of 1s per day. This discrepancy gave rise to considerable aggravation when many qualified miners were enlisted on the basic Sapper rate and miners who had initially enlisted as infantry, were transferred to Tunnelling Companies and paid as miner’s mates. Likewise when ‘miners mates’ acquired experience and were employed on the same basis as enlisted clay kickers.

Tunnelling Companies

By June 1916, when the British mining establishment neared its peak, 33 Tunnelling Companies had been raised as follows:-

  • 25 (Imperial) Tunnelling Companies RE
  • 3 (Canadian) Tunnelling Companies RCE
  • 3 (Australian) Tunnelling Companies RAE
  • 1 (New Zealand) Tunnelling Company RNZE
  • The Australian Electrical & Mechanical, Mining & Boring Company (The ABC Coy)
  • A Portuguese Mining Company was also incorporated in the BEF in 1917

At the peak (July 1916 to June 1917) there were between 30,000 and 40,000 men engaged on mining (and construction of subways & forward dugouts) in the British lines. Amongst all belligerents about 120,000 men were thus employed.

Working Underground

Underground Working Parties

Typically there would be 4 tunnellers working at the face (one of whom would be resting), plus 2 tunnellers mates handling trolley, air pumping and preparation of timber. Generally infantry working parties were employed to remove the spoil from the shaft heads and dispose of it. (One foot run of subway created 70 sandbags of spoil). At any time a Tunnelling Coy would have several digging parties working towards each other. A common pattern was that in each Section three of the four shifts would be in line, each for 4 days, and one shift resting or on light duties out of line for 4 days. Shifts normally worked underground for 8 hours in every 24 hours. The 16 hours ‘off’ included moving into and out of the line.

Tunnel Construction

This was influenced by many factors. As a rule of thumb a Tunnelling Coy would drive a subway, including side chambers, at about 20ft (6m) per day. Rates over double this were achieved on occasion. The British miners tried to strike a balance between sufficient space to work efficiently and minimizing the spoil to be removed. Fighting tunnels were generally between 4ft 6 ins and 5ft 2 ins high (1.4m to 1.6m) and 2 ft 6 ins to 3 ft wide (0.8m to 0.9m). There were though many variations depending on circumstances and tunnelling companies. For example the New Zealand Tunnelling Company preferred more head room. It was rare to construct crawl only tunnels, though sometimes in emergency (usually in clay) the miners would burrow what they termed ‘rabbit holes’. French miners tended to smaller tunnels than the British. Dimensions of German tunnels were similar or slightly larger than the British.

British practice was to use no more support than essential. In clay this did entail extensive timbering but in chalk, supports were only used at weak points or in fractured ground close to mine blows. In Flanders, where deep tunnels were driven through ‘Blue Lias’ (a form of clay) it was sometimes necessary to use steel girders to resist expansion pressure. German practice was to ‘close timber’ most tunnels regardless of support requirements, a procedure that slowed down their progress. When silent digging the chalk face was softened with water before pieces were prised out with a spike. This was a very slow process and rarely used.

Locating Enemy Tunnels

Ground is a good conductor of sound so by listening to sounds of enemy working and then taking compass fixes from several underground positions and obtaining an intersection it is possible to locate enemy activity. The most effective instrument for this was a French device known as a geophone. This comprised two pressure sensitive diaphragms with a tube leading from each to the ear of the listener. These would be moved until equal pitch was obtained in each ear. A bearing taken at right angles to the line between the two diaphragms would show the direction of the sound. Listeners (usually officers or Senior NCOs) were selected for their near perfect aural capability and trained for about six weeks at a special ‘listening school’. The procedure was remarkably accurate, and experts could even use it to determine differences of elevation. Numerous methods were employed by both sides to confuse or mislead the other, or to draw the opposing miners into an underground ambush. Listeners were involved in a very deadly game of bluff.

Explosives Guncotton and gunpowder was used in the early mines. However from early 1915 the British employed ammonal. This is a compound of 65% ammonium nitrate, 15% TNT, 17% coarse aluminium and 3% charcoal. It is an inert slow lifting explosive. To explode it has to be ‘hit’ by a powerful detonation wave, usually provided by guncotton primers. These in turn have to be initiated by detonators containing highly sensitive fulminate of mercury. Firing was usually with an electrical circuit. For some very large mines gelignite boosters were used. Ammonal was normally decanted from 50 lb tins into 25 lb rubberised bags clamped with wooden slats. Most of the ammonal found in the Vimy tunnels by the Durand Group is still in near prime Condition.

Intensity

In June 1916 (the peak month), along the line of the British front, the British fired 101 mines or camouflets; the Germans fired 126; a total of 227 in the month. This equals one mine every three hours.

Underground Working Parties

Typically there would be 4 tunnellers working at the face (one of whom would be resting), plus 2 tunnellers mates handling trolley, air pumping and preparation of timber. Generally infantry working parties were employed to remove the spoil from the shaft heads and dispose of it. (One foot run of subway created 70 sandbags of spoil). At any time a Tunnelling Coy would have several digging parties working towards each other. A common pattern was that in each Section three of the four shifts would be in line, each for 4 days, and one shift resting or on light duties out of line for 4 days. Shifts normally worked underground for 8 hours in every 24 hours. The 16 hours ‘off’ included moving into and out of the line.

 

Tunnel Construction

This was influenced by many factors. As a rule of thumb a Tunnelling Coy would drive a subway, including side chambers, at about 20ft (6m) per day. Rates over double this were achieved on occasion. The British miners tried to strike a balance between sufficient space to work efficiently and minimizing the spoil to be removed. Fighting tunnels were generally between 4ft 6 ins and 5ft 2 ins high (1.4m to 1.6m) and 2 ft 6 ins to 3 ft wide (0.8m to 0.9m). There were though many variations depending on circumstances and tunnelling companies. For example the New Zealand Tunnelling Company preferred more head room. It was rare to construct crawl only tunnels, though sometimes in emergency (usually in clay) the miners would burrow what they termed ‘rabbit holes’. French miners tended to smaller tunnels than the British. Dimensions of German tunnels were similar or slightly larger than the British.

 

British practice was to use no more support than essential. In clay this did entail extensive timbering but in chalk, supports were only used at weak points or in fractured ground close to mine blows. In Flanders, where deep tunnels were driven through ‘Blue Lias’ (a form of clay) it was sometimes necessary to use steel girders to resist expansion pressure. German practice was to ‘close timber’ most tunnels regardless of support requirements, a procedure that slowed down their progress. When silent digging the chalk face was softened with water before pieces were prised out with a spike. This was a very slow process and rarely used.

 

Locating Enemy Tunnels

Ground is a good conductor of sound so by listening to sounds of enemy working and then taking compass fixes from several underground positions and obtaining an intersection it is possible to locate enemy activity. The most effective instrument for this was a French device known as a geophone. This comprised two pressure sensitive diaphragms with a tube leading from each to the ear of the listener. These would be moved until equal pitch was obtained in each ear. A bearing taken at right angles to the line between the two diaphragms would show the direction of the sound. Listeners (usually officers or Senior NCOs) were selected for their near perfect aural capability and trained for about six weeks at a special ‘listening school’. The procedure was remarkably accurate, and experts could even use it to determine differences of elevation. Numerous methods were employed by both sides to confuse or mislead the other, or to draw the opposing miners into an underground ambush. Listeners were involved in a very deadly game of bluff.

Explosives Guncotton and gunpowder was used in the early mines. However from early 1915 the British employed ammonal. This is a compound of 65% ammonium nitrate, 15% TNT, 17% coarse aluminium and 3% charcoal. It is an inert slow lifting explosive. To explode it has to be ‘hit’ by a powerful detonation wave, usually provided by guncotton primers. These in turn have to be initiated by detonators containing highly sensitive fulminate of mercury. Firing was usually with an electrical circuit. For some very large mines gelignite boosters were used. Ammonal was normally decanted from 50 lb tins into 25 lb rubberised bags clamped with wooden slats. Most of the ammonal found in the Vimy tunnels by the Durand Group is still in near prime Condition.

 

Intensity

In June 1916 (the peak month), along the line of the British front, the British fired 101 mines or camouflets; the Germans fired 126; a total of 227 in the month. This equals one mine every three hours.

Hazards

More miners were probably killed and wounded by shelling and harassing fire on the surface than underground. The greatest subsurface killer was carbon monoxide (CO) poisoning, a consequence of gases from the mine and camouflet explosions. Of course many were killed by being crushed, buried or entombed. CO is particularly invidious being odourless, colourless, and slightly lighter than air. It combines with the haemoglobin of the blood to displace oxygen,  and also acts on the central nervous system. The effect is not immediately felt. A person exposed to even a very small proportion in the air becomes drowsy, and will then suddenly collapse. Unless quickly supplied with oxygen death inevitably follows.

To give warning of the presence of CO caged canaries and mice would accompany miners working underground. Both have a very high metabolic rate and are very sensitive to carbon monoxide and other gases. Some men even had their own personal mice that they kept in a pocket. The canary’s claws were always clipped so that on becoming unconscious they would fall off their perch. Usually they revived on return to good air and it was customary to ‘retire’ them as pets after a half dozen or so occurrences. Incidentally an escaped canary could compromise security in areas where mining was not suspected by the enemy and there are several recorded cases of artillery or mortars being used to ‘extinguish’ escaped birds. The miners in the deep tunnels were rarely troubled by war gases, but had to take exceptional precautions against ingress of gases (such as CO) from mine explosions which could leak a considerable distance into tunnels through cracks in the chalk. Consequently the deep mining systems were compartmentalised with gas doors which could be quickly released to seal an area. Pockets of CO still exist in the chalk today.

Ventilation was used extensively to combat CO and to provide fresh air into the tunnel systems. Methods varied, ideally employing an updraught process that provided natural ventilation. At gallery headings air was hand pumped in along metal pipes.A very extensive rescue system was set up and each Army had a Mine Rescue School. As a general rule of thumb, in mining areas, there was a mine rescue station to every 1000 yards of front. Rescuers where equipped with a ‘Proto’ breathing system and the Officers carried electric torches.

Water and flooding was also a serious problem and a lot of manpower effort (usually from attached infantry) had to be used for hand pumping – although power driven pumps were used when practicable. Sudden flooding was sometimes a risk, and men were on occasion drowned, particularly when trapped and rescuers could not get to them in time. However it was not one of the major hazards.

Casualties

181 mining officers lost their lives including 9 from the Canadian Coys, 12 from the Australian and 3 from the New Zealand. This is approximately 30% of front line strength. It is not known how many soldiers of the Tunnelling Coys died but around 3,000 would seem a fair estimate. Probably about one third of the casualties were incurred underground.

Types of Mine Explosions

There were three types of Mine charges:-

  1. OFFENSIVE
  2. DEFENSIVE
  3. TACTICAL

Offensive mines could be further subdivided into the COMMON mine and the FOUGASSE mine:

  • a COMMON mine was designed to blow up the enemy.
  • a FOUGASSE mine was designed to bury the enemy by throwing a large amount of debris over the enemy position.

Defensive mines were designed to destroy or disrupt enemy mining. This was usually done by placing a Camouflet charge close to the enemy tunnel. A ‘Camouflet’ is a subsurface charge which is designed to be contained in the earth and not break surface.

Tactical mines were not aimed at destroying the enemy. Usually these were to provide a high rim for firing positions overlooking the enemy, or conversely to screen off enemy positions, or to obstruct enemy approaches. A variation on the above themes are:

Bored Mines (usually known as Wombat mines from the hand drilling rig employed). These were mostly tactical; blown to provide a screened route across No-Mans-Land.