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.

[4] Towards the end of 1914, the civil engineering company of Member of Parliament and British Army Major, John Norton-Griffiths, was working on sewerage renewal contracts in Liverpool and Manchester.

[5] In early December 1914, Norton-Griffiths wrote to the War Office suggesting that the technique would be useful attack, spying or for intercepting German tunnels coming in the opposite direction.

[5] On 20 December 1914, by digging shallow tunnels under no man's land, German sappers placed eight 50 kg (110 lb) mines beneath the positions of the Indian Sirhind Brigade in Givenchy-lès-la-Bassée.

[5] Arriving with two of his employees at the GHQ Saint-Omer office of the Engineer-in-Chief (E-in-C), Brigadier George Henry Fowke, on 13 February, Norton-Griffiths gave another demonstration of "clay-kicking."

On arrival at the front line, (a mile from where the first German mine had exploded the previous December), they confirmed the excellent conditions of the clay-based soil and returned to St Omer via the four headquarters to communicate their findings.

[citation needed] To make the tunnels safer and quicker to deploy, the British Army enlisted experienced coal miners, many outside their nominal recruitment policy.

The desperate need for skilled men saw notices requesting volunteer tunnellers posted in collieries, mineral mines and quarries across South Wales, Scotland and the Northeast of England covering Derbyshire, County Durham,[10] Nottinghamshire and Yorkshire.

[1] A clay-kicking team typically consisted of three men:[1] a "Kicker" who worked at the face, a "Bagger" who filled sandbags with the lumps of clay spoil, and a "Trammer" who transported the bags out of the gallery on a small, rubber-tyred trolley on rails.

As no nails or screws could be used due to noise, the 'setts' (consisting of a sole, two legs and a cap), were sawn with a rebated step, which, once trimmed into the clay, would expand with the absorbed water into a solid structure.

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.

Towards the end of the tunnel war, forces also deployed mines at greater depths, which, coupled with the use of listening devices, could be exploded away from friendly trenches as a defensive measure.

While the bottom blue clay layer was virtually flat, as was the Kemmel Sands that sat on top of it, there was a dry strata which varied above this which created the geographical contours.

The British used tube shafts from May 1915, a full year before the Germans, who when they did start to use metal and concrete tunnels, had lost the strategic advantage and were digging purely for defensive purposes.

The small village of Hooge in Flanders belonged to one of the easternmost sectors of the Ypres Salient, which made it the site of intense and sustained fighting between German and Allied forces.

[18] In the Somme sector of the Western Front, local but very fierce underground fighting had taken place in the winter of 1914 and spring of 1915 at La Boisselle, Fricourt, Bois Français and Carnoy.

Secondly, they prepared a series of shallow Russian saps from the British front line into no man's land, which would be opened at Zero Hour and allow the infantry to attack the German positions from a comparatively short distance.

For the start of the battle on 1 July 1916, the Royal Engineers planned to fire a group of eight large and eleven small mines along the Somme front line.

At La Boisselle, the ruined village was meant to fall in 20 minutes, but by the end of the first day of the battle, it had not been taken while the III Corps divisions had lost more than 11,000 casualties.

Approximately 10,000 German troops were killed when the mines were simultaneously detonated, creating 19 large craters and an explosion so loud it was heard by British Prime Minister David Lloyd George in his study in 10 Downing Street in London.

As instructed, soldiers of the 36th (Ulster) Division had already left their trenches and begun to move across No-Man's Land when the mine exploded a few seconds late, leading to some being killed by falling debris.

[23] The British intended to dismantle the remaining mines, but the Third Battle of Ypres delayed operations, after the Germans overran the group headquarters their location was lost.

[34] Before the Battle of Vimy Ridge (9–12 April 1917), the British tunnelling companies secretly laid a series of explosive charges under German positions in an effort to destroy surface fortifications before the assault.

[39] 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.

[4] Even after mine warfare had stopped, 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.

[42] 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.

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.

The brick plinth bears transparent plaques with details of the mining activities by 172nd Tunnelling Company and an extract from the poem Trenches: St Eloi by the war poet T.E.