Thursday, 25 June 2015

Tunnel warfare in WW1

Trench warfare

World war 1 is known for it's brutal trench warfare in which opposing forces were dug in in front of each other in trench lines due to lack of mobility(Tanks, vehicles) with no man's land in between. Trenches were protected with barbed wires from enemy assault and no mans land was fully exposed to artillery fire from both sides.
The defender held the advantage in this form of warfare. Attacks even if successful suffered severe casualties
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The result of trench warfare was stalemate. The defender usually held his position while attacker could not make a breach in the defenses in most of the cases. Attacks were made with soldiers charging through no man's land towards enemy trenches only to be slaughtered with machine gun and artillery fire.

Breaking the stalemate (Use of tunnel warfare)

Due to lack of tanks( which only came into action in 1917) and air power, some innovative response to the attacker's problem was required. That innovative response was tunnel warfare.
This also came to be known as military mining.

Conducting tunnel warfare:
Tunnel warfare meant to dig tunnels across no man's land and place mines or explosives beneath the enemy trenches and detonate them which resulted in that particular section of trench being blown up. Take advantage of the confusion and casualties among enemy ranks and charge through no man's land and hope for the best.

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Diagram explaining Tunnel warfare

Sometimes, it could take as long as a year(or even more) to dig a tunnel and place a mine.

First use of tunnel warfare in WW1

Germans started the use of tunnel warfare first.
On 21 December 1914, at Givenchy-lès-la Bassée the Germans secretly dug shallow tunnels across No Man’s Land and exploded ten small but deadly mines( Camouflets) beneath the primitive trenches of the Indian Sirhind Brigade. As the news spread up and down the line, alarm increased: how could this new and unexpected threat be countered? It couldn’t – adequately – for at that time the British had no military mining corps. Further German blows in the new year spurred the British to react with uncharacteristic alacrity.

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The allies responded by forming their own tunneling companies by March 1915 and deployed them at Flanders.By the close of that year mine warfare was more or less continuous wherever opposing trench lines lay within mutual striking distance. It had already become a 24- hour a day, 365-day a year operation.

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Australian tunnellers in Ypres sector

By mid-1916 the British had around 25,000 trained tunnellers. Almost twice that number of ‘attached infantry’ worked permanently alongside them acting as beasts of burden, fetching and carrying the many essential elements of mining paraphernalia, pumping air and water and removing spoil – the earth produced by the digging of the tunnels.

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Group photo of British tunnellers

The miners were practically civilians with little to no military training.

Shafts
The standard and most simple shafts were built entirely in timber and conformed to centuries-old designs. Although adequate in firm and dry conditions, the varying geological nature of the Flanders battlefields demanded new techniques to cope with the serious problem of bad ground, particularly the layer of quicksand known as the Kemmel Sands, an integral component of the geological make up of all the ridges around Ieper. For the Germans, occupying almost all the most advantageous positions on the ridge tops, this stratum was a serious headache. Tunnelling in the dry strata above the Kemmel Sands was simple, swift and easy, but sinking a shaft through the schwimmsands, as they were known (the British called them running sands), to reach the dry and firm clay geology beneath, was found to be unfeasible: the constantly shifting ground made timber structures almost impossible both to stabilise and waterproof. The sands, which were trapped between the dry stratum above and impervious clay beneath, were also under great geophysical pressure, and often ‘fountained’ when pierced. Believing that the British faced the same insoluble engineering problem, the Pioniere made few efforts to break through the schwimmsands until the spring of 1916.

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Illustration of steel ‘tubbed’ shaft construction. Drawn by Andy Gammon

What the Germans had failed to realise was that their enemy had conquered the geology by using cylindrical steel shafts known as ‘tubbing’. Tubbing arrived in sections which were bolted together to form a watertight tube. These were sunk through the wet sands (see illustration above) to the dry clay beneath either by the gravitational action of their own weight, or by jacks. Once the steel had reached the dry clay it was again safe to continue the work in timber. The system was quick, simple, strong, stable and waterproof – and allowed the British to delve deep into the Flanders clay in many places where their enemy believed it to be impossible. Critically, the British first used steel shafts as early as May 1915 – almost a full year before the Pioniere. By the spring of 1916 when the Germans were forced to sink watertight shafts in steel (and concrete) because the British had started blowing deep mines, the subterranean war was effectively lost to them. In this ‘year of German ignorance’ the Tunnellers had been able to secretly drive many deep galleries and plant the greatest mines in the history of warfare.

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A steel ‘tubbed’ shaft at Lancashire farm near Ypres

Hazards of tunneling

Following were three main hazards to a miner's life and health in the tunnels beneath the battlefields.
  • Blown up by enemy tunnellers
  • Having fight with enemy tunnellers in pitch dark of the tunnels in close quarters.
  • Suffocating with excess of gasses ( Carbon dioxide and carbon mono oxide).
  • Health problems.
  • Buried alive because of some mishap.

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French soldiers in a tunnel


Gas( most threatning non combat risk)

Underground, tunnellers faced many a threat: entombment, obliteration, health problems brought on by the workload, working environment and poor air quality; there was even the risk of drowning. But the biggest killer was actually gas poisoning; not the designed toxic vapour variety used in cloud and shell form by troops on the surface, but carbon monoxide (CO), an invisible, odourless and tasteless substance that was naturally produced by every explosive action – even the firing of a simple rifle bullet. In mines that broke the surface, or in the case of a shell burst, carbon monoxide quickly dissipated into the atmosphere; after an underground explosion, however, it is trapped – in the geology and in the tunnels.

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Mine rescue team equipped with torches, bellows, short-range breathing gear, Novita oxygen resuscitation kit, Proto apparatus, ropes and a canary in a cage.

Effects of carbon mono oxide on tunnellers
Carbon Mnoxide displaces oxygen in the blood. The process is cumulative, resulting in body tissues being gradually starved of oxygen and energy. Death, when it comes, is painless, gentle and insidious, but in the tunnels it was a terrifying prospect. With lowlevel concentrations men could be entirely unaware of its presence, allowing them to penetrate deep into a system before being affected.

If the gas was present in large quantities, a tunneller could be unconscious in a matter of moments – with little warning. The early symptoms were giddiness, shortness of breath and palpitations, with confusion following. There was then a loss of power in the limbs. When this stage was reached a little exertion would induce loss of consciousness.

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Tunneller descending a shaft wearing Proto apparatus. A mouse or a canary would already have been used to detect the presence of carbon monoxide gas.

Fighting the "gas"
In extensive mine systems galleries were fitted with regulator doors, effectively producing a series of airlocks. The spread of gas could therefore be isolated so rescue work was simplified and tunnellers in unaffected areas could continue to operate. For rescue purposes several forms of self-contained breathing apparatus were used. However, it was first essential to find out whether the air below ground was ‘gassy’ or not. To achieve this Tunnellers employed the traditional practice of using canaries and mice. As both creatures have a much higher metabolic rate than humans, they are therefore more quickly affected by CO gas. Mice were superceded by canaries as signallers for their curling up in a corner of the cage was not sufficiently evident; a canary, however, was prone to fall off its perch, a more obvious indication of risk. The British eventually organised a highly developed system of rescue. In mining sectors no shaft was further than 200 metres from a station. Proto-men (named after the breathing kit they employed) were highly trained, hand picked men, selected for experience and coolness under pressure. Two men were on duty at all times. Apart from the rescue gear and oxygen reviving equipment each station contained: Ten electric miners lamps, six canaries (or mice) with four mobile cages and two living cages, one saw, one hand axe, three life lines, two mine stretchers, one trench stretcher, one Primus stove, two tins of café au lait, six hot water bottles, six blankets.

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A mine rescue station in Flanders with a sapper ready for descent and other equipment prepared for use. 

Countering the enemy miners

Any encounter with enemy miners would result in violent hand to hand fight in the tunnels, which no side wanted, so efforts were made to detect enemy tunnels before they do so.
The side which detected enemy tunnellers before usually prevailed by blowing enemy tunnels with mines.
To detect enemy tunnels, listening tactics were used.

Listening
There were two main listening techniques.
  • Listening with naked ear
  • Utilizing technical instruments like geophones, tele geo phones or seismomicrophones.
Listening became a highly developed and efficient art. Installed at the end of their tiny gallery, a trained listener would take notes of the compass bearing and estimated distance of suspect sounds. Comparing the notes of several listeners allowed triangulation of a sound’s origin, and thus an indication as to the location of the enemy, the direction he was heading, and the speed at which he was working. The favoured British listening aid was the Geophone (below). Employing two sensors a listener was able to ascertain the direction of hostile activity by moving the sensors until sound levels appeared 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.
By the end of 1916 the scale of mine warfare had expanded to such an extent that there were not enough listeners to man every post, and 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 recorded by just two men.

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A sapper using a geophone. Military Mining 1923


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French sappers listening

Dealing with enemy miners after detecting them


Heavy charges could not be used to destroy enemy tunnels because one’s own tunnel systems could be equally seriously damaged. Such tactics were used only in extremis, when the hostile threat was acute. This, therefore, was defensive mining, devised and adapted to protect ones own web of tunnels from enemy action.

When were heavy charges used:
Heavy charges were used, when the commanders wanted to either destroy substantial sections of hostile tunnels and the occupants, or make the ground so shattered that it was difficult to work. These bigger blows often cratered the surface.

Special "light charges" for tunnellers:
To kill or defeat enemy tunnellers, small, controlled and localised underground blasts were required, which would not break the surface and form craters, but to destroy a strictly limited area of underground territory – and its occupants.

The explosives charges used to achieve such results were called camouflets.

Two methods were employed to defeat enemy tunnellers:
  • Camouflets were used in one’s own tunnel, a listening post, or in a small spur which was specially dug towards suspect enemy sounds. This was the preferred method in tough ground such as hard clay, or the resilient chalks of Picardy.
  • The second method was more applicable in softer ground, especially in the sandy ridges and spurs of the Ypres (Ieper) Salient. Here, a ‘torpedo’ or ‘Cylinder’ was used. These were specially prefabricated self-contained explosive charges housed in a tube, designed specifically for this kind of warfare. Kept in a store at the rear of tunnel systems, at least one torpedo was always prepared for action, fully charged, primed with a detonator, and ready for instant use. Torpedoes were also used from shallow tunnels to destroy trenches and dugouts.
Delivering the decisive blow

Once having dug the tunnels successfully directly beneath the enemy trenches, heavy charges weighing hundreds of tonnes of explosives were used to cause a massive explosion beneath the enemy's trenches before the forces on the ground charge at them.​

Example of successful implementation of tunnel warfare

The battle of Messines is an example of the successful implementation of tunnel warfare by British miners.

It has been argued that the Battle of Messines was the most successful local operation of the war, certainly of the Western Front. Carried out by General Herbert Plumer's Second Army, it was launched on 7 June 1917 with the detonation of 19 underground mines underneath the German mines.
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Gen Hubert Pulmer

The target of the offensive was the Messines Ridge, a natural stronghold southeast of Ypres, and a small German salient since late 1914.

In preparing for the Messines battle he had authorised the laying of 22 mine shafts underneath German lines all along the ridge, his plan being to detonate all 22 at zero hour at 03:10 on 7 June 1917, to be followed by infantry attacks so as to secure the ridge from the presumably dazed German defenders, the infantry heavily supported by the use of artillery bombardments, tanks and the use of gas. Work on laying the mines began some 18 months before zero hour.

One mine, at Petite Douve Farm, was discovered by German counter miners on 24 August 1916 and destroyed. A further two mines close to Ploegsteert Wood were not exploded as they were outside the planned attack area.

In the face of active German counter-mining, 8,000 metres of tunnel were constructed under German lines. Occasionally the tunnellers would encounter German counterparts engaged in the same task: underground hand to hand fighting would ensure.

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Heavy shelling of the German lines was begun on 21 May, involving 2,300 guns and 300 heavy mortars, ceasing at 02:50 on the morning of 7 June. The German troops, sensing imminent attack, rushed to their defensive positions, machine guns ready, meanwhile sending up flares to detect British movement towards the ridge.

Silence prevailed for the following twenty minutes until, at 03:10, the order was given across the line to detonate the mines, which totalled 600 tons of explosive. Of the 21 mines laid 19 were exploded.

The effect of the mine explosions upon the German defenders was devastating. Some 10,000 men were killed during the explosion alone.
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German trench destroyed by a mine explosion
All initial objectives were taken within three hours.
the first time on the Western Front that defensive casualties actually exceeded attacking losses: 25,000 against 17,000.

The explosions are said to have registered on a seismograph in Switzerland, and were heard by David Lloyd George over 150 miles (241 km) away in Downing Street, London.

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Spanbroekmolen crater in November 2009. It was created in 1917 by one of the mines in this battle. It is also known as "Lone Tree Crater" or "Pool of Peace".

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