On the Western Front during the First World War, the military employed specialist miners to dig tunnels under No Man's Land. The main objective was to place mines beneath enemy defensive positions. When it was detonated, the explosion would destroy that section of the trench. The infantry would then advance towards the enemy front-line hoping to take advantage of the confusion that followed the explosion of an underground mine.
Soldiers in the trenches developed different strategies to discover enemy tunnelling. One method was to drive a stick into the ground and hold the other end between the teeth and feel any underground vibrations. Another one involved sinking a water-filled oil drum into the floor of the trench. The soldiers then took it in turns to lower an ear into the water to listen for any noise being made by tunnellers.
It could take as long as a year to dig a tunnel and place a mine. As well as digging their own tunnels, the miners had to listen out for enemy tunnellers. On occasions miners accidentally dug into the opposing side's tunnel and an underground fight took place. When an enemy's tunnel was found it was usually destroyed by placing an explosive charge inside.
Mines became larger and larger. At the beginning of the Somme offensive, the British denoted two mines that contained 24 tons of explosives. Another 91,111 lb. mine at Spanbroekmolen created a hole that afterwards measured 430 ft. from rim to rim. Now known as the Pool of Peace, it is large enough to house a 40 ft. deep lake.
In January, 1917, General Sir Herbert Plumer, gave orders for 20 mines to be placed under German lines at Messines. Over the next five months more than 8,000 metres of tunnel were dug and 600 tons of explosive were placed in position. Simultaneous explosion of the mines took place at 3.10 on 7th June. The blast killed an estimated 10,000 soldiers and was so loud it was heard in London.
Le Touquet consisted of a number of huge mine craters, roughly between the German front line and our own. In some cases the edge of one crater overlapped that of another. Companies of Royal Engineers, composed of specially selected British coal miners, worked in shifts around the clock digging tunnels towards the German line. When a tunnel was completed after several days of sweating labour, tons of explosive charges were stacked at the end and primed ready for firing. Careful calculations were made to ensure that the centre of the explosion would be bang under the target area.
This was an underground battle against time, with both sides competing against each other to blast great holes through the earth above. With listening apparatus the rival gangs could judge each other's progress, and draw conclusions. A continual contest went on. As soon as a mine was blasted, preparations for a new tunnel were started. On at least one occasion British and German miners clashed and fought underground, when the final partition of earth between them suddenly collapsed.
On the completion of one of the mines, the troops in the danger area withdrew when zero time for detonation was imminent. If the resultant crater had to be captured, an infantry storming party would be ready to rush forward and beat Jerry to it. Some of the craters measured over a hundred feet across the top, descending funnell-wise to a depth of at least thirty feet.
At the moment of explosion the ground trembled violently in a miniature earthquake. Then, like an enormous pie crust rising up, slowly at first, the bulging mass of earth crackled in thousands of fissures as it erupted. When the vast sticky mass could no longer contain the pressure beneath, the centre burst open, and the energy released carried all before it. Hundreds of tons of earth hurled skywards to a height of three hundred feet or more, many of the lumps of great size. A state of acute alarm prevailed as the deadly weight commenced to drop, scattered over a huge radial area from the centre of the blast.
WWI's Battle of Messines: How Allies Used Massive Explosives and Tunneling to Win
The Western Front of World War I is infamous for trench warfare, long and grueling battles fought from dug-in positions separated by no man’s land. But a lesser-known type of battle also raged underground as both Allied and German forces dug extensive networks of secret tunnels in order to plant explosive mines beneath the enemy’s feet.
The Battle of Messines in July of 1917 witnessed what was arguably the single largest explosion of the pre-atomic age, when 19 underground mines packed with an estimated 1 million pounds of high explosives erupted beneath the German line, killing untold numbers of soldiers and shattering German morale before the real fighting even began.
The Long, Long Trail
The war on the Western Front bogged down into siege conditions by November 1914. Both sides faced the need to break through the enemy’s defensive entrenched positions. It was not long before an ancient art was remembered and used most effectively: mining under the enemy lines, placing explosives and blowing them up. In some areas, both sides mined and counter-mined intensively. For the infantry above ground, the wait for underground explosions was nerve-wracking indeed for the men underground, hard toil often came accompanied by sudden death.
The first use of underground mine warfare
The pre-war British army had no specific organisation for carrying out sapping, mining and tunnelling operations, although most men of the Royal Engineers received some training in the subject. Digging beneath an enemy position with the object of destroying it is essentially an act of siege warfare, and military planning did not believe that this was a serious possibility. However, by the end of 1914 it was clear that the entrenched positions of the Western Front were akin to siege conditions.
On 20 December 1914 ten small mines – each subsequently discovered to have been 50kg of explosive, driven under the British positions from saps in the German front-line system – were blown at Givenchy. An infantry attack followed, and over 800 men of the Indian Corps were lost. By January 1915, it was evident that the Germans were beginning to mine on a definite system.
On 3 December 1914 the commanding officer of IV Corps, Sir Henry Rawlinson, requested the establishment of a special battalion to assist with mining duties. On 28 December, in the tense time following the first German mine attacks, Major John Norton Griffiths – a larger than life character, formerly an MP and an officer of the 2nd King Edward’s Horse – suggested the hiring of ‘clay kickers’, men with a particular skill who had been employed in mining for the London Underground. Meanwhile the army was ordered to proceed with offensive mining operations using any suitable personnel they could find from within the ranks. These men were formed intoBrigade Mining Sections. On 17 February 1915 the first British mine was blown at Hill 60 by RE troops of 28th Division.
The first Tunnelling Companies are formed
A decision was taken in February 1915 to form eight Tunnelling Companies, made up of men drawn from the ranks, mixed with drafts of men specially recruited for this kind of work. This has been described as the quickest intentional act in the war: men who were working underground as civilians in the UK on 17 February were underground at Givenchy only four days later, such was the urgency of needing countermeasures against the aggressive German actions. Another twelve Companies were eventually formed in 1915, and one further one in 1916. A Canadian Tunnelling Company was formed in France and two more arrived from home, by March 1916. Three Australian and one New Zealand Tunnelling Companies arrived on the Western Front by May 1916. All of these units were engaged on underground work including the digging of subways, cable trenches, saps, chambers (for such things as signals and medical services), as well as offensive or defensive mining. A Mine Rescue School was formed in Armentieres in 1915.
Underground warfare develops
Once both sides had embarked on mining operations, there was a determined struggle for tactical superiority in those areas where conditions were favourable. At Hill 60, The Bluff, St Eloi, Aubers Ridge, Hooge, Givenchy< and Cuinchy, where the front lines were relatively close together and the geology suitable for tunnelling, the mining companies sought ways to not only drive mines for destroying enemy positions, but developed measures of detection of the enemy mine systems. When detected, an enemy mine would be immediately destroyed by the explosion of a camouflet, often at the cost of severe damage to ones own system. There were many underground encounters, as a tunnelling team, breaking into an enemy position, met the enemy underground. Sometimes these encounters included fighting in the tunnels and chambers.
The blowing of mines below enemy front line positions became a regular feature of local actions. Infantry tactics developed that would enable the rushing and capture of the crater formed by the explosions. The craters were often themselves a dominant ground feature, as the lip of earth thrown up was usually higher than the ground in the area, giving possible observation over the enemy. Crater fighting became a highly dangerous and unpleasant feature of many actions in 1915 and early 1916.
Mining in support of larger infantry offensives was also adopted, with increasing numbers of mines of increasing size being used in the first minutes of the major British attacks at Aubers Ridge (May 1915), Loos (September 1915) and the Somme (July 1916). Gradually, the British tunnellers gained ascendancy.
Craters – legacy of mine warfareSome impression of the scale of the Lochnagar Crater, blown on 1 July 1916 at La Boisselle on the Somme, can be made by comparing the crater slope and depth to the tiny figures of people on the lip. The aim was to destroy large areas of enemy trenches and to disorientate the defenders. Mining warfare reached its zenith in June 1917, when 19 huge British mines blew under the Messines Ridge. The Messines craters still exist and are now deep pools. This is Kruisstraat numbers 1 and 4 mines. Tunnellers of the Royal Engineers had dug from 1500 feet from behind the British line to reach this strong point under the enemy trenches. 49500 pounds of explosive, mostly ammonal, buried 57 feet below the surface, blew at 3.20am on 7 June 1917. This photo kindly supplied by Iain McHenry.
After the immense and successful demonstration at Messines of the superiority that the Tunnelling Companies had achieved, there was relatively little mining activity. This was largely due to the return to a more fluid war of movement in which siege methods became irrelevant. The tunnelling troops were more often engaged in construction work, and in creating underground subways for infantry to shelter in and to reach the front lines without molestation. In the crises of Spring 1918, they were often called upon to act as emergency infantry. When the tables turned and the Allies began to advance in late July 1918, they worked on making safe the many towns, villages and facilities they captured, including the very dangerous work of rendering harmless the many explosive devices that had been left behind.
Principal areas of mining activity in France and Flanders
|Northern sectors: |
between Ypres and Armentieres
|Central sectors: |
between Armentieres and Arras
|Southern sectors: |
on the Somme battlefield
French and German mining extended down into the Champagne, the Argonne and further south. A particularly impressive site, with extensive remains of craters and underground galleries, is the mine-riven hill at Vauquois.
The history of the Tunnelling Companies RE
Please note that the movement details described below have some gaps – and no doubt some inaccuracies. If anyone can help fill in the missing details, please contact me.
The Epic Struggle to Tunnel Under the Thames
At the beginning of the 19th century, the port of London was the busiest in the world. Cargoes that had traveled thousands of miles, and survived all the hazards of the sea, piled up on the wharves of Rotherhithe—only for their owners to discover that the slowest, most frustrating portion of their journey often lay ahead of them. Consignments intended for the southern (and most heavily populated) parts of Britain had to be heaved onto creaking ox carts and hauled through the docklands and across London Bridge, which had been built in the 12th century and was as cramped and impractical as its early date implied. By 1820, it had become the center of the world’s largest traffic jam.
It was a situation intolerable to a city with London’s pride, and it was clear that if private enterprise could build another crossing closer to the docks, there would be a tidy profit to be made in tolls. Another bridge was out of the question—it would deny sailing ships access to the Pool of London—and ambitious men turned their thoughts to driving a tunnel beneath the Thames instead. This was not such an obvious idea as it might appear. Although demand for coal was growing fast as the industrial revolution hit high gear, working methods remained primitive. Tunnels were dug by men wielding picks in sputtering candlelight.
No engineers had tunneled under a major river, and the Thames was an especially tricky river. To the north, London was built on a solid bed of clay, ideal tunneling material. To the south and east, however, lay deeper strata of water-bearing sand, gravel and oozing quicksand, all broken up by layers of gravel, silt, petrified trees and the debris of ancient oyster beds. The ground was semi-liquid, and at depth it became highly pressurized, threatening to burst into any construction site.
Richard Trevithick, the Cornish engineer who made the first—disastrous—attempt at a Thames tunnel.
Today, engineers deal with treacherous ground by pressurizing their workfaces (though that solution still leaves tunnelers vulnerable to the problems that come from working in high-pressure environments, including bone-rot and even the bends). In the early 19th century, such measures were still decades away. The first men to attempt a tunnel beneath the Thames—gangs of Cornish miners brought to London in 1807 by businessmen banded together as the Thames Archway Company—had little to guide them.
The chief engineer of this first tunnel project was a muscular giant named Richard Trevithick, a self-educated man who had progressed from youthful fame as a Cornish wrestler by displaying a dazzling talent for invention. Trevithick had harnessed steam power to drive the first self-propelled engine to run on rails and designed the world’s first high-pressure steam engine. He was convinced that a tunnel could be hacked out under the Thames relatively easily. It did not take long for him to realize he was wrong.
Trevithick’s men made fine progress while tunneling through London clay, but once they got under the Thames they had constant trouble. Their pilot tunnel was just five feet high and three feet wide, and sewage-laden water seeped in from the river, thirty feet above their heads, at the rate of 20 gallons a minute. Within this narrow space three miners worked on their knees, one hewing at the face with his pick, another clearing away the sodden earth, the third shoring up the drift with timbers. Working conditions during the six-hour shifts were appalling the men were soaked with sweat and river water, no one could stand or stretch, and the tunnel was so poorly ventilated that the fetid air sometimes extinguished the candles.
A miner inside Trevithick's cramped Thames driftway.
Nevertheless, the Cornishmen made progress, and by January 1808 Trevithick reported that his drift was within 140 feet of the north bank of the Thames and that the pilot tunnel would be completed in a fortnight. Then things began to go disastrously wrong. The miners hit quicksand, then water, this time in such quantity that nothing could stop waterlogged soil from gushing into the driftway. The men at the face fled the shaft just ahead of the flood.
Correctly guessing that his tunnel had come too close to an unexpected depression in the bed of the Thames, Trevithick arranged for the hole to be plugged with large bags of clay dumped into the river. To the astonishment of his detractors, this seemingly desperate measure worked, and the tunnel was pumped dry. Within days, however, it flooded again, and this time the Thames Archway Company had had enough. Its funds were exhausted, its chief engineer was sick from exposure to the river water, and all its efforts had proved only that a passage under the river at Rotherhithe exceeded the limits of contemporary mining technology.
At that time, the only machines used in mines were pumps. It took a man of genius to recognize that a different sort of machine was needed—a machine that could both prevent the roof and walls from collapsing and hold back any quicksand or water at the tunnel face. This man was Marc Brunel, an emigré who had fled his native France during the Revolution and quickly made a name for himself as one of the most prominent engineers in Britain.
Brunel was a tiny, eccentric man, impractical in his private life but an intensely able innovator. His inventions, which had brought him to the attention of men as illustrious as Tsar Nicholas I of Russia, included machines for mass-producing cannon balls, embroidering fabric, sawing wood and making ships’ tackle. This last had cut the cost of producing rigging pulleys by 85 percent. After he secured a number of contracts to supply pulleys to the Royal Navy, the Frenchman found himself relatively wealthy despite his lack of business acumen.
Marc Brunel, father of the celebrated shipbuilder and railway engineer Isambard, was a notable engineer in his own right. Image: Wikicommons.
Not long after the failure of the Thames Archway Company, Brunel happened to be wandering through the Royal Dockyard at Chatham when he noticed a rotten piece of ship’s timber lying on the quay. Examining the wood through a magnifying glass, he observed that it had been infested with the dreaded teredo, or shipworm, whose rasping jaws can riddle a wooden ship with holes. As it burrows, this ‘worm’ (it is actually a mollusk) shoves pulped wood into its mouth and digests it, excreting a hard, brittle residue that lines the tunnel it has excavated and renders it safe from predators.
Though he had no prior knowledge of or interest in the subject, Brunel realized that the shipworm’s burrowing technique could be adapted to produce an entirely new way of tunneling. His insight led him to invent a device that has been used in one form or another in almost every major tunnel built during the last 180 years: the tunneling shield. It consisted of a grid of iron frames that could be pressed against the tunnel face and supported on a set of horizontal wooden planks, called poling boards, that would prevent the face from collapsing. The frames were divided into 36 cells, each three feet wide and almost seven feet tall, and arranged one atop another on three levels. The whole machine was 21 feet tall, and the working surface was 850 square feet times bigger than Trevithick’s.
The shield was topped by sturdy iron plates that formed a temporary roof and protected the miners as they worked. Instead of hewing away at a large and exposed surface, they would remove one poling board at a time and hack out a mailbox-shaped hole to a predetermined depth—say nine inches. Then the board would be pushed into the hole and screwed back into place before the next one was removed and the whole process begun again. When the miners in a cell had excavated the earth behind all of their boards, their frames could be laboriously jacked forward those nine inches. In this way, the whole 90-ton tunneling machine could move inexorably and safely on while masons trailed behind, shoring up the newly exposed tunnel with bricks.
A model of Marc Brunel's tunneling shield on display at the Brunel Museum at Rotherhithe, London. Photo: Wikicommons.
The prospect of tunneling beneath the Thames promised a lucrative test of Brunel’s new invention, and he raised funds for the project through a public subscription. Soil samples were taken beneath the riverbed, and Brunel was advised to stick close to the muddy river bottom, where he could expect clay, rather than risk striking quicksand by going deeper. When he began work on his tunnel in 1825, the shaft that was sunk in dingy Rotherhithe was only 42 feet deep, and it was planned to pass within seven feet of the river bed in places.
The hazards of such an operation soon became apparent. Although the shield worked well and the miners dug, at first, through the predicted clay, water began to drip into the tunnel before the shaft had even begun to pass under the Thames. This influx was more of a nuisance than a real danger while the pump was working, but in the summer of 1826 it failed, and the whole shaft was soon flooded to a depth of 12 feet.
From then on the project proved ever more difficult. Brunel’s machine could cope with the sodden mud and dry gravel that his miners encountered nearly as well as clay, but he ran short of funds. The economies that followed left the shaft was poorly drained and ventilated, and miners were poisoned by the polluted river water or afflicted by illnesses ranging from diarrhea and constant headaches to temporary blindness. Most of Brunel’s workers complained of feeling suffocated and tormented by temperatures that could plunge or rise by as much as 30 degrees Fahrenheit within an hour. One miner died of disease.
In May 1827, with the tunnel now well out into the river, the ground behind the poling boards became so liquid that it forced its way through the gaps between the boards a gusher in one of the cells bowled the miner working in it head over heels. The rest of the 120 men working in the shield could not force their way into his frame in time to staunch the flow. Bitter-tasting, gurgling water rose rapidly and flooded the tunnel, sending all the miners scurrying for their ladders and the surface.
The diving bell used by Brunel to plug a hole in the bottom of the Thames.
Brunel, like Trevithick, recognized that his tunnel had passed beneath a cavity in the riverbed, and he too solved his problem with bags of clay. Thousands, containing a total of 20,000 cubic feet of earth, were dumped into the river over the shield’s position, and two weeks after the flood his men began to pump the tunnel dry. It took four months, and when work was restarted in November, a highly publicized banquet for 50 guests was held in the tunnel. Thousands of visitors were permitted to enter the shaft and gaze at the wonderful tunneling machine on payment of a penny a head. The tunnel’s construction became news worldwide Edward Lear, traveling through the mountains of Calabria, stopped for the night in a lonely monastery run by an abbot who informed his monks: “England is a very small place, altogether about the third the size of the city of Rome…. The whole place is divided into two equal parts by an arm of the sea, under which is a great tunnel so that it is all like one piece of dry land.”
Work at the face began again late in 1827, but within months the shield was advancing through treacherous ground once more. Early in the morning of January 12, 1828, the miners in one of the top cells were hacking away when another unstoppable torrent of water flooded into the tunnel. Once again the men in the shield had to run for safety, but this time they had left it too late six miners were drowned. Just as seriously for Brunel, the cost of tipping a further 4,500 bags of clay into the Thames to plug this latest hole in the river bed exhausted his company’s funds. With no new financing in the offing, the tunnel was pumped dry, the shield was bricked up and the tunnel was abandoned.
The interior of the tunnel was later occupied by vagrants and known grimly as "Hades Hotel".
It took Brunel and his supporters seven years to cajole the government into advancing a loan of 𧶮,000 to allow work on this “project of national importance” to be completed. And despite the replacement of the old tunneling shield with a new model better able to resist the pressure of the Thames as it swelled with each high tide, it took six more years of round-the-clock labor before the tunnel finally emerged at Wapping on August 12, 1841. Work on the 1,200-foot tunnel thus occupied 16 years and two months, an average rate of progress (allowing for the seven-year layoff) of only 4 inches a day—a good measure of how sorely the project tested the technology of the day.
Brunel’s triumph was only partial. Once again his company’s funds were at a low ebb, and the tens of thousands of penny-a-head visitors hardly paid the interest on the government loan There was never enough to complete the approaches to the tunnel and make it accessible to horse-drawn vehicles, as intended. Instead, the passageways were filled with souvenir-sellers by day and by the city’s homeless at night. For a penny toll, vagrants could bed down under Brunel’s arches in what became known as the Hades Hotel.
It was only when the underground railway came to London in the 1860s that the Thames Tunnel achieved a measure of real usefulness. Purchased by the East London Railway in 1869, it was found to be in such excellent condition that it was immediately be pressed into service carrying steam-driven trains—at first along the Brighton line and later from Wapping to New Cross. The tunnel became, and remains, part of the London Underground network. It is a tribute to Trevithick and Brunel—and mute testimony to the difficulties of tunneling in London—that it remained the only subway line so far to the east until the opening of the Jubilee Line Extension in 1999.
Counter tactics [ edit | edit source ]
Listening [ edit | edit source ]
Early tunnelling required a great deal of improvisation, as equipment was in short supply. This made tunnels shallow, the noise of digging being detectable using simple devices in the trenches, even amongst the gun-fire.
In the trenches, soldiers found that driving a stick into the ground and holding the other end between their teeth enabled them to feel any underground vibration. Another method involved sinking a water-filled oil drum into the floor of the trench, with lookout soldiers taking turns to lower an ear into the water to listen for vibrations. Improvised methods later included Water Board inspector short-sticks, each with a single vibrating wire-type earphone attached, or using filled French water-bottles laid flat on their sides in pairs, so they could be listened-to through medical stethoscopes. Ζ]
Underground, within the tunnelling operations, side-shaft listening posts were deployed and manned by soldiers whose job entailed listening for indications that the enemy was tunnelling. Initially using just manual methods, the British were eventually equipped with the Geophone, which could detect noises up to 50 metres (160 ft) away. Employing two Geophones, a listener was able to ascertain the direction of hostile activity by moving the sensors until sound levels were equal in both ears. A compass bearing was then taken. When gauging distance only, both earpieces were plugged into a single sensor this was a skill only gained by experience. Ώ]
Deploying listeners in different tunnels in triangulation techniques, by the end of 1916 the scale of British tunneling warfare had expanded to such an extent that there were not enough listeners to man every post central listening stations were devised. Working electronically like a telephone exchange, the signals from up to 36 remote sensors (Tele-geophones and Seismomicrophones) could be distinguished and logged by just two men. Ώ]
Underground tactics [ edit | edit source ]
The tunnellers developed counter tactics, which both sides deployed. The first was the use of large mines placed in one's own tunnels – some actually dug towards enemy noise to create damage – which when exploded would create fissures and cracks in the ground, making the ground either unsuitable for tunnelling or destroying existing tunnels and works. A small device, called the camouflet, created a localised underground chamber designed not to break the surface and form craters, but to destroy a strictly limited area of underground territory – and its occupants. Ώ]
The second tactic, deployed when the enemy tunnel was too close to your existing works or trenches, was the deployment of rod-fed torpedo shaped camouflet charges. Effectively land mines on the end of long iron sticks, the technique was a defensive tactic against an immediate threat. Towards the end of the tunnel war, forces also deployed mines at greater depths, which together with listening devices could be exploded away from friendly trenches as a defensive measure. Ώ]
In siege warfare, tunnelling is a long-held tactic for breaching and breaking enemy defences. The Greek historian Polybius, in his Histories, described accounts of mining during Philip V of Macedon's siege of the town of Prinassos there is also a graphic account of mining and counter-mining at the Roman siege of Ambracia. Mining was a method used in siege warfare in ancient China from at least the Warring States (481–221 BC) period forward. 
In 1215 during the First Barons' War, John, King of England laid siege to Rochester Castle. Eventually, he ordered his troops to dig a tunnel under the south tower, which they held up with pit props. After the tunnellers lit the props, the tower fell down, ending the siege even though the castle's main walls remained standing.
In 1346, Edward III of England requested that miners from the Forest of Dean, Gloucestershire accompany his expedition to France,  during the first part of the Hundred Years' War between England and France.
The Corps of Royal Engineers were formed in 1717. In 1770, the Company of Soldier Artificers formed a specialist tunnelling troop in Gibraltar to dig defensive positions into the Rock. 
During the Siege of Lucknow in 1857, Royal Engineers were asked to undertake counter-mining. 
- Mines were scene of underground fighting as portrayed in the Sebastian Faulks novel
- Excavations uncovered intact tunnels - and the bodies of four German soldiers
Flanders fields today bears little sign of the four years of war that claimed so many thousands of lives and ravaged this small corner of the Western Front.
But further down, deep below the surface there remains a constant reminder of the bravery and daring of the men who risked their lives for their country.
Beneath the farmers ploughs, most of the tunnels and dug-outs hewn from the earth by English pitmen to literally undermine the German offensive remain intact, untouched for almost 100 years.
They were also the scene of fierce hand-to-hand combat between diggers from both armies, as portrayed in the Sebastian Faulks novel Birdsong.
The tunnel sealed off by British troops during the First World War was excavated in 1997 and found to be intact
Tunnel engineer Johan Wanderwalle discovered that the tunnels had flooded, but remained intact in the 80 years after the First World War
The British Tunnelling Companies were formed in the early months of the war to counter the German miners who were blowing British trenches from shallow underground workings.
Pitmen from mining communities in Wales and the north and the ‘clay-kickers’ who built the London Underground and the Manchester sewers were recruited, some from infantry battalions others direct from civilian life.
Not only did, they offered vital support to the war effort, providing protected shelter for the troops.
By the time Armistice came the secret underground army had dug mile after mile of tunnel and hundreds of deep dug-outs designed to house headquarters, hospitals, stores and men.
The excavation uncovered a number items that had belonged to German soldiers such as bottles, a shoe, digging tools and even a gun and some bullets
Still intact: Another shot of the items discovered in the tunnel, seen from another angle - spades presumably used to carve out the tunnel can be seen on the left
Leftovers: A close up of the various items discovered in the tunnel, including a shoe and some bottles
These never seen before images of one of the tunnels were taken by British photographer Jeff Moore during an excavation with tunnelling engineer Johan Wanderwalle in 1997.
And the story behind the tunnel found by Mr Wanderwalle echoes the action in Birdsong, an adaptation of which is currently being screened by the BBC.
The tunnel was being dug by British troops to undermine the Germans who were diggning in the opposite direction , Mr Moore told Mail Online.
But the German soldiers realised what was happening and changed course and dug into the clay-kickers’ tunnel before the British troops had a chance to lay explosives.
Dramatised: A still from BBC adaptation of Sebastian Faulks' classic novel Birdsong showing British troops in the tunnel
In the novel Birdsong, Stephen Wraysford (played by Eddie Redmayne, pictured, in the current BBC adaptation) is trapped by an explosion in an underground tunnel
This picture, taken in 1915, shows diggers making a bore-hole for a secondary chamber, intended to cause the enemy tunnel to fall in
There was an underground fight before the British soldiers pulled out and sealed up the tunnel.
Such fighting was not uncommon. With so much mining activity being carried out by both sides, detection and breakthrough into each others tunnelling systems occurred frequently.
For this purpose the British diggers prepared a 'camouflet', a pre-prepared charge which was always ready during tunnelling.
If that wasn't detonated, vicious hand-to-hand fighting with picks, shovels and wood used as makeshift weapons might take place.
The restrictions and conditions of the underground tunnels meant the miners could not use their rifles.
If the opposing side were unsuccessful in repelling an attack, then enemy tunnels could be used for short periods to observe enemy tunnelling activity and direction.
During the 1997 excavation Mr Wanderwalle found a number of items belonging to the Germans - as well as the bodies of four dead soldiers.
Mr Wanderwalle said: ‘Above ground everything was cleaned up and re-built after the war and there is no sign that anything happened here but once you get underground you find everything just as it was all those years ago.’
'My first one was in 1990. No one had done it before then so my friends and I had to learn how to work underground. The entrances were filled up with earth and rubbish after the war so you have to carefully dig them out.
Haunting: Tunnel engineer Johan Wanderwalle stands inside the water logged tunnel which he explored with photographer Jeff Moore 15 years ago
'Once you get past the entrance you find everything is as it had just been left, as if it had just happened. The waters came in and flooded it and preserved everything just as if it was yesterday.
'I have done so many now I can look at the entrance to a tunnel and I know by the way the timbers are arranged which of the Tunnelling Companies built it but inside everyone is different, you never know what you'll find.'
One of the first World War survivors who was involved in protecting the tunnels first hand was Albert 'Smiler' Marshall who was serving in the trenches with the Essex Yeomanry in 1915 when he was caught in a mine blast.
Remnants of war: Tunnel engineer Johan Wanderwalle holds a rifle found in the tunnel
Albert 'Smiler' Marshall was serving in the trenches with the Essex Yeomanry in 1915 when he was caught in a mine blast - he was found after singing Nearer My God To Thee
THE UNDERGROUND EFFORT
Royal Engineer tunnelling companies were specialist units of the Corps of Royal Engineers within the British Army, formed to dig attacking tunnels under enemy lines during the First World War.
The stalemate situation in the early part of the war led to the deployment of tunnel warfare.
After the first German Empire attacks on 21 December 1914, through shallow tunnels underneath no man’s land and exploding ten mines under the trenches of the Indian Sirhind Brigade, the British began forming suitable units.
In February 1915, eight Tunnelling Companies were created and operational in Flanders from March 1915.
By mid-1916, the British Army had around 25,000 trained tunnellers, mostly taken from coal mining communities.
Almost twice that number of ‘attached infantry’ worked permanently alongside the trained miners to carry out grunt work.
From the spring of 1917 the war became more mobile, with grand offensives at Arras, Messines and Passchendaele.
The tactics and counter-tactics required deeper and deeper tunnelling, so offensive and defensive military mining largely ceased.
Underground work continued, though, with the tunnellers concentrating on deep dugouts for troop accommodation, a tactic used particularly in the Battle of Arras.
His experience was not dissimilar to that of Stephen Wraysford, the character from Sebastian Faulk novel Birdsong, who gets caught up in a blast from underground mines with his friend, a tunneller called Jack Firebrace.
In an interview before he passed away 'Smiler' said: ‘We knew there was tunnelling going on around and about because our engineers were working there and we used to help them with carrying parties and protection and that sort of thing.
'Somehow or other our intelligence got to know there was a German mine underneath us and when they were going to blow it up we came out of that section of trench but we didn't come out far enough because we didn't know exactly the spot where it was or how much explosive they had.
'There was this terrific bang and it made a damn great crater you could drop a house into and two of our chaps got buried there. Others got buried with just their two legs, some were up to their waist and one had only just got his head out.
'I got hit. I'd have been alright if I hadn't fell down only there was so much dirt came down on us it knocked me on my back and as I laid on my back in the trench my leg got trapped and I couldn't move it.
'Eventually it settled down a bit and someone shouted “is Smiler alright?”, so I shouted out that I'm quite alright but I can't move and I'm lying on my back in the trench and I've got to wait 'till someone comes to dig me out.
'The voice was shouting "tell him to sing" so that was how they found me, lying down there singing Nearer My God To Thee. Two men were buried completely and that was their grave, we didn't have time to bury them properly.'
Smiler's comrades joined the list of 54,896 ‘missing British soldiers who still lie in the fields in Ypres, their names recorded on the nearby Menin Gate, their bodies obliterated by shellfire or hastily interred in shallow graves and never found by the burial parties on their grim rounds after the war.
Discovery: The 'Birdsong tunnel' was explored by Jeff Moore and Johan Wanderwalle in 1997
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End of mining operations
From Spring 1917 the whole war became more mobile, with grand offensives at the Battles of Arras, Messines and Passchendaele, there was no longer a place for a tactic that depended upon total immobility for its employment. As the tactics and counter-tactics required deeper and deeper tunnelling, (hence more time and requiring more stable front lines), offensive and defensive military mining largely ceased.
Underground work continued, with the tunnellers concentrating on deep dugouts for troop accommodation, safe from the larger shells being deployed.
According to the original trench maps, hospitals, mess rooms, chapels, kitchens, workshops, blacksmiths, as well as bedrooms where exhausted soldiers could rest, were hewn from the blue-clay and stone. Connected by corridors measuring 6 ft 6in high by 4 ft wide, they were fitted with water pumps which, when the troops left within weeks of the war ending, were slowly submerged. The developments at Hill 60 housed 3,000 men, those near Hooge 1,000. A brigade headquarters at the Vampire dugout near Zonnebeke, was captured and occupied by the Germans in their Spring Offensive in 1918, before being retaken in September. The level of activity can be gauged by the fact that during 1917 and 1918, more people lived underground in the Ypres area than reside in the town today. 
Battle of Arras
In preparation for the Battle of Arras in 1917, the Royal Engineers had been working underground from October 1916, constructing tunnels for the troops.  The Arras region is chalky and therefore easily excavated under Arras itself there is a vast network of caverns (called the boves), which consist of underground quarries, galleries and sewage tunnels. The engineers devised a plan to add new tunnels to this network so that troops could arrive at the battlefield in secrecy and in safety.  The scale of this undertaking was enormous: in one sector alone four Tunnel Companies (of 500 men each) worked around the clock in 18-hour shifts for two months.
The British attack plan was well developed, drawing on the lessons of the Somme and Verdun in the previous year. Rather than attacking on an extended front, the full weight of artillery fire would be concentrated on a relatively narrow stretch of 24 miles (39 km). The barrage was planned to last about a week at all points on the line, with a much longer and heavier bombardment at Vimy to weaken its strong defences.  During the assault, the troops would advance in open formation, with units leapfrogging each other in order to allow them time to consolidate and regroup. Before the action could be undertaken, a great deal of preparation was required, much of it innovative.
To assist the attack, the Royal Engineers constructed 20 kilometres (12 mi) of tunnels, graded as subways (foot traffic only) tramways (with rails for hand-drawn trollies for taking ammunition to the line and bringing casualties back) and railways (a light railway system).  Just before the assault the tunnel system had grown big enough to conceal 24,000 men, with electric lighting provided by its own small powerhouse, as well as kitchens, latrines and a medical centre with a fully equipped operating theatre.    The bulk of the work was done by New Zealanders, including Maori and Pacific Islanders from the New Zealand (Māori) Pioneer Battalion,  and Bantams from the mining towns of Northern England. 
Assault tunnels were also dug, stopping a few yards short of the German line, ready to be blown open by explosives on Zero-Day.  In addition to this, conventional mines were dug under the front lines, ready to be blown immediately before the assault. Many were never detonated for fear that they would churn up the ground too much. In the meantime, German sappers were actively conducting their own underground operations, seeking out Allied tunnels to assault and counter-mine.  Of the New Zealanders alone, 41 died and 151 were wounded as a result of German counter-mining. 
Today, most of the tunnels and trenches are off-limits to the public for reasons of safety. A 250 metre portion of the Grange Subway at Vimy Ridge is open to the public from May to November and the Wellington tunnel was opened to the public as the Carrière Wellington museum in March 2008.  
Second Battle of Passchendaele
In preparation for the Second Battle of Passchendaele, as early as the 17 October, assault units were given all available details about the German defences in their respective sectors, in order to facilitate early planning. Intelligence officers and artillery observers worked jointly in observation posts recording newly built German fortifications as well as those that had previously escaped notice, permitting the artillery to take necessary action before the offensive.  To improve the logistical movement of artillery and supplies an extensive programme of road building was started. Ten field companies, seven tunnelling companies, four army troop companies and nine battalions were put to work repairing or extending existing plank roads. From the middle of October until the end of the offensive, a total of 2 miles (3.2 km) of double plank road and more than 4,000 yards (3,700 m) of heavy tram line was constructed in the Canadian Corps area.  Brigadier General Edward Morrison, commanding the artillery, also secured permission to use the roads to the rear for withdrawing disabled guns for repair. 
History of the sprayed concrete lining method—part II: milestones up to the 1960s ☆
In this part, first the origin and development of rock anchors are described. Their history began with a patent application in 1913 in Germany. The breakthrough in application came, however, only in the 1940s from the American mining industry. The first application of systematic rock bolting in a tunnel was the diversion tunnel for the Keyhole Dam in the USA in 1950. This paper describes numerous examples of civil engineering work world-wide with early application of rock bolting. It is shown how the combined application of the new support elements—steel arch, sprayed concrete and anchors has led to the ‘sprayed concrete lining’ method in the 1950s. In concluding, it is demonstrated that the so-called ‘New Austrian Tunnelling Method’ (NATM), which has been propagated since 1963, is in many respects borrowed and has created much confusion amongst professional engineers by dint of its pseudo-scientific basis.