BEF & CEF Tunnelling Companies

While World War I witnessed the development of new combat technologies such as the tank and airplane, both sides also reverted to a strategy not employed for centuries.  The practice of tunnelling was part of siege warfare tactics dating back to ancient Greece, Rome and China, and was a key element in Middle Ages conflicts.  As modern warfare moved onto open battlefields, the strategy fell into disuse. 

Several factors led to its revival during the opening months of World War I.  German strategists expected a quick victory on the Western Front following their surprise invasion of Belgium and northern France in early August 1914.  Their hopes were dashed when desperate British and French forces managed to halt the advancing German army mere kilometres from Paris.  By December 1914, both sides found themselves entrenched along a front stretching from the English Channel to the Swiss border.  Military commanders on both sides began a desperate search for a strategy that would break this stalemate and lead to a final victory.

Two additional factors led to the revival of tunnelling as a military strategy.  In order for its use to be effective, opposing front lines had to be close to one another and geological conditions suitable.  Three particular sectors on the front lines provided such circumstances - the northern sectors from Ypres, Belgium to Armentieres, France; the central sectors from Armentieres to Arras; and the southern sectors of the Somme battlefield.

Mining locations in Ypres - Armentiers Sector

The Germans were the first to implement this strategy in an attack near Givenchy, France.  Tunnelling from their forward observation posts - known as "saps" - under opposing British trenches manned by the Indian Corps, the Germans placed ten explosive charges, each weighing 50 kilograms.  On December 20, 1914, the mines were simultaneously detonated.  The explosion and subsequent infantry attack inflicted 800 casualties on the surprised defending troops.  The incident revealed that the Germans had adopted tunnelling as a strategy on the Western Front.

Mining Sites in the Armentiers - Arras Sectors

The Allied response was predictable.  While the Royal Engineers were skilled in the construction of saps, basic tunnelling and mining operations, no "specialized" units existed.  British commanders immediately set about organizing the first of several "tunnelling companies" specifically trained to dig tunnels and plant mines under enemy lines.

Mining Sites in the Somme Region

On December 28, 1914, British Major John Norton Griffiths, a former Member of Parliament, civil engineer and officer with the 2nd King Edwards' Horse, suggested to British commanders that the army hire 'clay kickers' - men who employed in digging the London Underground as well as sewage systems in British cities - to conduct tunnelling operations along the Western Front.  In the meantime, commanders identified qualified individuals - men with mining experience - who had already enlisted, forming temporary "mining sections" within each brigade until tunnelling companies could be recruited and deployed.

Major Griffiths meanwhile set about organizing the first "tunnelling team" from amongst former employees of his civil engineering firm.  In peacetime, his company had constructed small-bore tunnels for sewage systems in England and Scotland.  When one such operation ceased on February 17, 1915, eighteen experienced 'clay kickers' were laid off, only to immediately enlist in the British army and be transported to the front lines in France four days later.  In recruiting the initial companies, Griffiths deserves credit for persuading British military authorities to focus on mining skill and overlook shortcomings (age, physical stature, discipline) that may have disqualified the men from military service.  Their later successes were proof of his foresight and sound judgment of character.

Coincidentally, the first British mine was detonated by British engineers of the 28th Division at Hill 60, near Ypres, Belgium, on February 17, 1915.  The event signified the adoption of tunnelling as a military strategy on the Western Front.  Subsequently, both sides constructed tunnels under enemy lines, laying explosive charges for detonation in co-ordination with infantry attacks.  At the same time, the armies implemented strategies to detect and destroy enemy tunnelling operations.

Diagram of typical tunneling operation. (Source: Spartacus Educational website.)

In the same month as the first successful mining operation, British commanders officially approved plans to create nine Tunnelling Companies.  The first units were formed by integrating men within existing ranks with individuals specifically recruited for the task.  A total of twelve companies were in the field by the end of the year, with an additional unit created in 1916.  Each consisted of 5 officers and 270 "sappers", assisted by infantrymen who served as labourers. 

Recruitment focused on civilians with mining skills, regardless of age.  Men who were well beyond "fighting years" thus found themselves part of the war effort.  Their skills, honed in British coal mines, were soon apparent.  British tunnelling companies dug at an average rate of 8 metres (8.7 yards) a day, as compared to the German rate of 2 metres (2.2 yards).  Many of the men who provided support labor were "bantams" - individuals rejected for infantry duty due to their small stature, but ideally suited for work in cramped, underground tunnels.

Several "colonial" tunnelling companies were also organized in 1916, Canada contributing a total of three units.  The 1st Canadian Tunnelling Company was raised from Eastern Canadian recruits and trained in the Ypres Sector before relieving the British 182nd Tunnelling Company near Armentieres, France in March 1916.  The 2nd Canadian Tunnelling Company was recruited in British Columbia and Alberta and deployed at the front lines in April 1916.  The 3rd Canadian Tunnelling Company was formed from mining sections initially created within the 1st and 2nd Canadian Divisions. It received its first assignment at St. Marie-Cappel, France in January 1916.  One New Zealand and three Australian tunnelling companies arrived on the Western Front by May 1916.  By the end of the year, a total of 30 Allied tunnelling companies were actively working in the combat zone.

Setting explosives in a tunnel.

Tunnelling companies first worked in the Ypres Salient, where mining conditions were ideal.  By April 10, 1915, British units had laid six mines, containing a total of 4500 kg (10 000 lbs.) of ammonal explosive, beneath German lines at Hill 60.  The resulting explosion generated a tremor that split the ground under the entire hill, producing flames that reached 90 meters into the sky as well as a 21-meter (70-foot) crater on the battlefield.  The surrounding German trenches instantly collapsed, crushing soldiers where they stood.

For the next two years, both sides dug tunnels under enemy lines.  The primary strategy - placement and detonation of mines beneath enemy positions - became a standard part of attacks in areas suitable for tunnelling.  Infantry immediately rushed forward to capture the crater created by the explosion.  "Crater fighting", as it became known, played a central role in many 1915 and 1916 battles.  Mines were also employed in support of larger infantry assaults at Aubers Ridge (May 1915), Loos (September 1915) and the Somme (July 1916).  The goal was straightforward - destroy sections of enemy trench and create panic among defenders as infantry advanced across the battlefield.

Each side also employed "counter-mining" strategies as the war progressed.  Soldiers in the trenches drove a stick into the ground, holding the upper end in their teeth to detect underground vibrations indicating underground activity.  A second detection method involved sinking a water-filled drum into the trench floor, soldiers lowering an ear into the water to listen for sounds below.  A third method used filled water bottles placed on the trench floor and medical stethoscopes to listen for underground activity.  Tunnellers often dug "side-shaft" listening posts to detect enemy tunnelling operations in the same area.  The British later developed a device called the "Geophone", capable of detecting underground noises at a distance of 50 metres.

Entrance to a German tunnel near Champagne, France.

Perhaps the most effective method of countering enemy tunnelling was the "camouflet".  Charges were routinely placed inside tunnels as they were constructed, in some instances in sections dug toward suspected enemy mining.  When detonated, the explosion created "fissures" beneath the surface, making the ground unsuitable for tunnelling.  If an enemy tunnel was detected, detonation of a small camouflet produced a chamber that collapsed the enemy tunnel below without creating a surface crater.  Another strategy utilized iron rods to push small, torpedo-like charges into the floor of a counter-tunnel.  Detonation destroyed the tunnel below without affecting the surface landscape.

While all tunnelling units engaged in setting underground explosives, their efforts were not limited to mining.  The men also dug subways, cable trenches, saps, and underground chambers for signal or medical services.  In suitable locations, extensive networks of tunnels were dug behind Allied front lines, allowing for movement of men and supplies into the front trenches without enemy detection. 

The best example of tunnelling efforts assisting a Canadian attack occurred at Vimy Ridge.  In the months prior to the April 9, 1917 attack, tunnelling companies dug an incredible 20 kilometres (12 miles) of subways for foot traffic, tramways equipped with rails for moving ammunition to the front lines and evacuating wounded soldiers, and light railways - all concealed from the enemy.  The tunnelling system housed 24 000 men prior to the attack and was equipped with electric lighting, kitchens, latrines and a medical centre.  A 250-metre section of the Grange Subway has been preserved and is accessible to the public at Vimy Ridge in recognition of the tunnelling companies' pivotal role in this milestone Canadian victory.

Underground chamber near Arras, France.

A 'clay kicking' team consisted of three men.  A 'kicker' worked the tunnel face with a device fastened to the soles of his feet, his back supported by a board.  As he cut chunks of soil from the tunnel face with a downward kick, he passed the earth over his head to a 'bagger' who dumped the debris into sandbags and loaded them into a cart.  A 'trammer' pushed the loaded, rubber-tired trolley along a small-gauge rail to the surface, where supporting labourers dispersed the load.  On its return journey, the cart carried timber for tunnel supports positioned every 9 inches as construction proceeded.  The miners worked in 6 or 12 hour rotating shifts, often under cover of darkness on the surface so as to conceal earth disposal from enemy aircraft.

Needless to say, tunnellers endured challenging working conditions.  Usually operating by candlelight as electricity was in short supply, the men toiled in silence so as to avoid enemy detection.  The tunnels were cold, cramped and damp, frequently containing significant amounts of water that seeped from above.   Detonation of enemy camouflets was a constant danger.  In some instances, miners accidentally broke through into an enemy tunnel, resulting in intense fighting metres beneath the battlefield. 

Tunnellers were also prone to several ailments.  The men suffered from high rates of "trench foot" and other podiatry ailments caused by damp working conditions.  Fatigue from the demanding physical labor was common.  In addition, carbon monoxide gas from artillery shells and bullets seeped through the soil into the tunnels, creating the potential for asphyxiation or deadly explosions.  Mice and canaries were officially issued to tunnelling companies in order to detect the presence of gas.

Detonation of Lochnagar mine at the Somme - July 1, 1916.

 Mines tunnelled under enemy lines played a key role in several 1916 and 1917 battles.  On March 27, 1916, six mines were detonated under German positions near Messines, Belgium.  The largest - dug by the 1st Canadian Tunnelling Company - was located at St. Eloi and contained 43 400 kg (95 600 lbs.) of explosives.  The resulting blast created the infamous "St. Eloi Craters", which Canadian infantry quickly occupied and struggled to defend, as the men were exposed to enemy artillery fire.

Prior to the launching of the Somme offensive, tunnelling companies placed ten explosive charges beneath German positions along the Hawthorne Ridge, near the French village of Beaumont Hamel.  At 7:26 am July 1, 1916, engineers detonated the explosives located in the tunnels.  Two minutes later, British and colonial troops advanced across 'no man's land" toward the German front lines.

Tunnelling strategy reached its apex at Messines, Belgium in June 1917.  In January, British companies began digging 22 mines beneath German lines, some as long as 660 metres (2160 feet) and at depths of up to 38 metres (125 feet).  In total, the miners dug more than 8000 metres of tunnels, in some cases starting as far as 460 metres (1500 feet) behind British front lines.  A total of 600 tonnes of ammonal explosives were set in place.  At 3:10 am June 7, 1917, 19 mines were detonated, causing an estimated 10 000 German casualties.  The subsequent explosion was so loud that it was reportedly heard in London.  A 40 000 kg (90 000 lb.) mine placed beneath German lines at Spanbroekmolen, near Messines, created a crater 132 metres (430 feet) in diameter and 12.5 metres (40 feet) deep.  Today, it is preserved as a memorial known as the "Pool of Peace".

Contemporary picture of Lochnagar Crater

The Messines mines marked the beginning of tunnelling's decline.  British tunnelling companies had clearly demonstrated their superiority over German mining efforts.  More importantly, the war entered a more "fluid" stage in which the front lines were set in motion.  Major Allied offensives at Arras, Messines and Passchendaele in 1917, followed by the German 1918 "spring offensive" and the Allied counter-attack of August 1918, destroyed the stalemate upon which tunnelling depended for implementation.

As a result, in July 1917, British military commanders decided to disband many of the tunnelling companies and reassign their personnel to other engineering or infantry units.  The few remaining companies continued to work on underground subways and shelters for front line infantry.  One such facility at Hill 60 accommodated up to 3000 soldiers.  During the German spring 1918 offensive, several tunnelling companies were pressed into duty as "emergency infantry".  By June 1918, as Allied forces slowly began to advance into German-held territory, companies cleared tunnels and shafts of enemy explosives left behind as German forces retreated.

After the war's end, many craters remained as part of the French and Belgian landscape.  The largest on the Western Front - Lochnagar Crater, on the Somme battlefields - was used as a garbage dump for years before it was privately purchased and restored as a historic battlefield site in 1979.  In several locations, unexploded Allied and German mines still lie beneath the surface of the landscape.  On July 17, 1955, one such mine in the Messines area was struck by lightning and exploded, killing one cow and damaging local property but thankfully causing no human casualties.  Other Allied and German mines have never been located, leaving tonnes of unexploded charges somewhere beneath the former battlefields of World War I.

A section of subway at Vimy Ridge.

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Further Information:

Visit the following BBC News article for information on the archaeological exploration of tunnels near La Boiselle, France, where both sides participated in mining and counter-mining activities throughout 1915 and 1916:

WWI Underground: Unearthing the hidden tunnel war

The BBC link below contains a short video of the tunnels being explored by British and French archaeologists at La Boiselle, France.

Excavating tunnels from World War I

Visit the following website to view a six-minute video of engineers exploring a WWI tunnel system near Loos, France.

The Durand Group: Descending into a multi-level WWi tunnel system at Loos

The following web site highlights the service of World War I tunnellers from the Ballarat region of Australia.  The Facebook page contains a variety of interesting photographs and items from the war.

Mining Mud & Medals - Facebook Page

Sources:

The Tunnelling Companies RE.  The Long, Long Trail: The British Army of 1914-1918 - for family historians.  Available online.

Tunnelling and the First World War.  Spartacus Educational.  Available online.

Tunnelling Companies of the Royal Engineers.  Wikipedia: The Free Encyclopedia.  Available online.