The War Fought by Ear

In December 1914, German sappers dug shallow tunnels under the Indian Sirhind Brigade at Givenchy-lès-la-Bassée and detonated ten mines simultaneously. The blasts and the infantry assault that followed cost approximately 800 casualties. The British had no answer. They didn’t even have a question yet. The war above was already a stalemate of artillery and wire. A second war had just opened underneath it.

Within two months, Major John Norton-Griffiths — a mining contractor and Conservative MP — was sitting on the floor of Lord Kitchener’s private office with a coal shovel from the fire grate, demonstrating a technique called clay-kicking. You lie on an angled wooden board, brace your back against it, and kick a sharp-bladed spade into the clay face with both feet. It’s fast. It’s almost silent. The men who knew how to do it had built the London Underground and the Manchester sewers.

Kitchener sent Norton-Griffiths to France the same day. By February 21, 1915 — four days after recruitment began — eighteen former sewer workers from a cancelled Manchester contract were digging tunnels in France. No basic training, no age restrictions, relaxed fitness standards. They were paid six shillings a day — six times what an infantryman earned. The British army was acknowledging, in the most direct way it could, that these men’s civilian skills were worth more than soldiering.

By war’s end, thirty-two tunneling companies existed across the British Empire forces: twenty-five British, three Australian, three Canadian, one New Zealand. Twenty-five thousand trained tunnelers, plus nearly fifty thousand attached infantry doing the hauling. On the British front alone, that was seventy-five thousand men underground at peak operations — and the French and Germans had their own.

The work

A tunnel team was twelve men under an NCO. Three at the face — kicker, shoveler, spoil carrier. Three on the rail cart, two disposing of spoil at the shaft mouth, one cranking the air pump. Work ran twenty-four hours a day in three shifts. The tunnels were small — often not much more than four and a half feet high. You crawled, crouched, or lay on your back for the entire shift.

The offensive work was straightforward in concept: dig from behind your own lines, under no man’s land, beneath the enemy’s position. Place a charge. Detonate it before an infantry assault. The counter-mining was more intimate: detect an enemy tunnel and destroy it with a camouflet — a small charge designed to collapse the gallery without breaking the surface.

But the hardest work was neither of these. It was listening.

The war by ear

The infantry war was fought by sight — over the parapet, across no man’s land, through binoculars and periscope. The underground war was fought by ear. You couldn’t see the enemy. You could hear him.

The early methods were improvised. Drive a stick into the ground and hold the other end between your teeth to feel vibrations through bone conduction. Sink water-filled oil drums into the tunnel floor and lower your ear to the surface. Press a medical stethoscope against a French water bottle laid flat on the ground.

Later, the geophone became standard: two wooden discs containing mercury between mica plates, connected by rubber tubes to earpieces. The listener knelt in absolute darkness, placed the discs on the ground, and slowly moved one in an arc until the sound reached equal intensity in both ears. Triangulation. You could estimate the bearing and distance of digging on the other side.

The operational rule was this: when you could hear the enemy talking, that was good. They were just working. When the talking stopped, they were probably laying a charge.

Think about that. The sound of men digging toward you was reassurance. Silence was the threat. The normal relationship between quiet and danger was inverted. Every silence in every tunnel became a question with lethal stakes: are they resting, or are they about to kill me?

What the earth cost them

Carbon monoxide killed more tunnelers than combat. Colorless, odorless, tasteless — generated by any underground explosion or even a single gunshot in a confined space. At 0.2% concentration, unconsciousness in twenty-five minutes. Over 1%, unconsciousness in two or three breaths, death in under three minutes. They used canaries and mice, same as civilian miners. The practice was identical. The context was not.

When opposing tunnels met — the last partition of earth collapsing without warning — men fought hand-to-hand in darkness, in spaces too small to stand. Poison gas was pumped into enemy tunnels with devastating effect because there was nowhere for it to go.

On May 4, 1917, French artillery sealed both ends of the Winterberg tunnel, trapping more than 270 German soldiers of the 111th Reserve Regiment. Over six days, as oxygen thinned, men asphyxiated or asked their comrades for mercy killings. Three survived long enough to be pulled out. The tunnel’s location was identified from archival maps around 2009; its entrance was physically opened in 2020. Nine soldiers have been identified. Germany has declined to excavate the site.

Sapper William Hackett of the 254th Tunneling Company was a coal miner for twenty-three years, rejected three times for being too old, enlisted in October 1915 despite a diagnosed heart condition. On June 22, 1916, a German mine blew in twenty-five feet of tunnel, trapping five men thirty-five feet underground. After two days of rescue digging, a hole formed. Hackett helped three men to safety. He refused to leave the fourth, who was badly injured. “I am a tunneller,” he said. “I must look after the others first.” The gallery collapsed. Rescue teams worked four more days. They never reached them. He has no grave. His body is still underground. He is the only tunneler to have received the Victoria Cross.

Messines

The operation that ended the underground war took nearly two years to prepare. Twenty-five mines prepared along an arc beneath Messines Ridge. Tunnels driven eighty to one hundred twenty feet down into a band of blue clay. Eight thousand metres of gallery — nearly five miles of tunnel beneath German positions. Approximately 454 tonnes of ammonal packed into underground chambers.

At 3:10 a.m. on June 7, 1917, nineteen of the twenty-one mines fired within twenty seconds. The blast was heard in London. In France, the shockwave was mistaken for an earthquake. General Harington had told his officers the night before: “We shall certainly alter the geography.”

Historian Simon Jones’s research corrects the commonly cited figure: not 10,000 Germans killed instantly, but approximately 2,800 in the blasts themselves, with 7,200 of the “missing” actually taken prisoner. The survivors emerged — in contemporary accounts — too shocked to fight. Archaeological evidence found trenches containing pulverized bone. The Spanbroekmolen crater, 430 feet rim to rim, is now called the Pool of Peace. It contains a forty-foot-deep lake.

What’s still down there

Of the mines prepared for Messines, six were not detonated: four at the Birdcage cluster, deemed unnecessary; La Petite Douve, abandoned after German counter-mining destroyed four hundred feet of gallery; and Peckham, abandoned after repeated flooding. The La Petite Douve charge — 50,000 pounds of ammonal — sits eighty feet beneath a rebuilt farm. Peckham’s 20,000 pounds sits beneath another. These are live, armed mines in steel drums, sealed in Flanders clay for over a century. Farmers work the fields above them.

On June 17, 1955, lightning struck an electrical pylon that had been erected unknowingly above one of the Birdcage mines. The current traveled down the steel-armored detonator conduit sixty-five feet underground and triggered the charge. The explosion destroyed infrastructure and killed livestock. No human casualties — by luck, not design. The mine had been sleeping for thirty-eight years, waiting for something to wake it. Five of its siblings are still down there.

What the war made of them

Victor asked what the war made of these men. The honest answer is something the language didn’t have a word for.

They went in as miners — men whose knowledge of darkness, confined space, and the behavior of earth was a civilian trade. They came out as something else. Not soldiers, exactly. The infantry war of rifles and artillery and wire had a vocabulary, a culture, a literature — the war poets wrote about it, the memoirists remembered it, the painters captured it. The underground war produced almost none of that. It was too claustrophobic, too specific, too alien to the experience above.

What the war did was take an intimate skill — knowing how clay sounds when it’s wet, how timber creaks before it fails, how air moves differently when a passage is blocked — and turn it lethal. The same knowledge that built sewers and rail tunnels now calculated blast radii and listened for the sound of enemy picks. The skill was identical. The context destroyed men.

The tunnelers suffered what we now call PTSD at rates that, even by the standards of a war that invented shell shock, were extreme. Not from the violence specifically — the infantry saw worse on the surface. From the conditions the violence occurred in. Darkness. Confinement. The inversion of silence and safety. The knowledge that the earth itself, which they had trusted their entire working lives, was now the medium through which someone was trying to kill them.

The British clay-kickers could dig twenty-six feet per day. The Germans managed six and a half. That four-to-one speed advantage was decisive. It was also the measure of how thoroughly the war had colonized a peacetime skill: the men who were fastest at building tunnels were fastest at building weapons, and the quality that made them valuable — their intimacy with the ground — was the quality that put them in the worst place the war had to offer.

The craters are still there. The bodies are still there. The mines are still there. The earth took what the war gave it and held on.

— Cael