by Will Davies
The tunnel started out at roughly two metres wide by one metre high, but to increase the pace it was soon reduced to 1.2 metres by 0.6 metres. While the clay kickers sweated at the face, men quietly dragged out the spoil, rolling it back on small trolleys that ran on wooden rails. The clay was then bagged, dragged to the surface and taken back behind the line. It was camouflaged so that the region’s distinctive blue clay would not give the enemy a hint of the depth or location of the mining operations.
Within the shaft, the air was dank and difficult to breathe. They had tried using mechanical bellows to pump in fresh air, but the miners worried that the rhythmical woofing would alert the Germans. It also made listening for German countermining difficult. Much like Hill 60, the ground was perforated by shafts and galleries, and German tunnellers were often working just metres away. Lieutenant Cassels could be found alone at the face, listening and gauging the location and direction of the German tunnelling. He lay with his face pressed into the clay, straining to hear any movement in the earth that would betray the enemy. The atmosphere was stifling, claustrophobic and frightening – a few inches above his head, the damp clay, and above that, ten metres of heavy earth weighing down upon him.
Apart from the tiny area lit by the flickering candle, around him was silence and darkness. Cramped as he was, he could feel the wet, cold earth all around him, just above his head and tight on his shoulders. And the ground seemed to murmur and move and close in on him. It was so very, very close. Movement was difficult. He lay prone on the clay floor of the tunnel, his head pressed against the face, listening, listening. His heart thumped and often it was hard to differentiate this from those other diverse and confused sounds around him. As he says in his diary: ‘Some sound could be heard, dull and muffled. There was always that fraction of a second of doubt – where it might be enemy mining. One’s pulse rate quickened and fright pushed to the fore one’s whole being.’4
While the main tunnel drove forward and under the larger concrete redoubt, the branch tunnel, due to the poor calculations and primitive survey equipment, was found to be in the wrong position for laying a charge that would destroy the smaller redoubt. With no time to dig a new branch tunnel, Cassels had a serious problem, one that could only be solved with a ‘bold and risky’ action, as he put it.5 If he could not destroy the second redoubt directly, perhaps he could bury it in debris – but for this he needed a massive explosion.
He found the answer in a little-known explosive charge called ammonal, never before used by the British army. All Cassels really knew about it was that it was composed of 75 per cent ammonium nitrate, with aluminium and TNT, and had a rate of detonation of five kilometres per second and over three times the lifting power of gunpowder. However, he had no real idea of the capabilities of the explosive given the depth of his tunnel and the weight and composition of the German redoubt. He calculated that he would need about 1.5 tonnes of this mystery substance.
The first problem was to get a supply of it. Cassels put in the necessary paperwork to the quartermaster general at GHQ, and his request quickly became an embarrassing issue. ‘Ammonal’ was confused with the drug ‘Ammonol’, used extensively in America ‘as a sedative in cases of abnormal sexual excitement’.6 You can imagine the poor quartermaster thinking that if they needed over a tonne of the stuff something strange was certainly going on along the front among those troublesome unionist miners.
The confusion was eventually straightened out, and the quartermaster dispatched the ammonal to the front. But when the ignition deadline was only three days away, there was still no sign of the ammonal, and Cassels raced around seeking alternative explosives for his tunnel. He received a signal to say his ammonal had been dispatched and should have arrived on a wagon already. Concerned at its delay, he frantically searched for the shipment. It was now daylight so a slow-moving wagon, whatever its cargo, was fair game for the ever-vigilant German gunners. At the last moment, the wagon appeared out of the low ground fog, to the great relief of Lieutenant Cassels. The driver explained he had been delayed because he’d had a problem with one of the wheels.
The ammonal was unpacked and lugged into the mine, down the narrow, slippery tunnel, and stacked in the dark, grim blue-clay gallery. The explosive was in 70 tin containers sealed with pitch, as it was very susceptible to moisture. The tins were stacked up like a mountain and spread among them were 24 detonators in batches of six. Each detonator was about 2.5 centimetres long and half as thick as a finger. These were connected to two sets of electrical firing leads, or fuses, that ran back to a communication trench. When the handle of the exploder was depressed in the communication trench, a current would pass down the firing leads, the detonators would explode and the charge would ignite the tins of ammonal.
Cassels worked quietly and diligently in the trench, testing and re-testing the circuit with a weak torch battery. The assaulting troops shifted nervously on their start tapes in nearby trenches and shell holes, apprehensive about the size and fallout from the explosion. The tunnellers retreated to a safe distance, prepared themselves and watched the seconds tick down. All was ready.
Suddenly, a German heavy-calibre shell crashed into no-man’s-land, throwing dirt, barbed wire and timber high into the air. Horrified, Cassels tested the line – there was no reading. It was minutes before zero hour, and after all the work, the pain, the fear, the great mine was dead. He tested again and the circuit was still dead. Frantically Cassels, along with another officer and a corporal, ran back into the explosive-packed tunnel. He could imagine the assaulting troops sweating anxiously as they huddled low beneath their parapets, trusting that his mine would obliterate the Germans and thus save their lives, but right now there was no mine, no explosion, and zero hour would be their end.
His hand found the firing wires in the yellowish glow of the torch beam. Next to him, the corporal ran these wires through his fingers, following them towards the German line. He found the break, clean and neat across the two electrical firing wires, and quickly set to work crudely joining the ends together. They raced back along the damp, timber-lined tunnel to the shaft, climbed the steep wooden ladder and gulped in the clear air above. Again they tested the circuit. The faint continuity test showed that the repair had worked. They were back in business.
Cassels got into firing position, his exploder in his hand. He looked at his watch. There were just over four minutes to zero hour. He watched the hand slowly tick by and wondered at the birds singing in the peaceful dusk of summer. Not 100 metres away, the Germans were beginning their dinner. He’d caught the smell of fried meat, of sizzling fat and the aromatic tobacco his enemy so often enjoyed. Just a pity about the ammonal lode beneath their feet.
At exactly 7 pm his plunger went down. The massive mine exploded. High into the air went the trench line of the Germans: trees, timber, barbed wire and tumbling bodies. No sooner had the debris landed than German artillery, well aware of the attacking troops, opened up. Shells blasted the British line as Cassels ran back along a narrow communications trench, past the wounded attacking troops, and made his way to the relative safety of Sanctuary Wood.
The explosion had been massive, so massive he wondered whether the frontline of the attacking British troops had been buried along with the Germans. He soon found out that ten men of the 4th Middlesex who were positioned in an exposed trench had been buried by the falling dirt and debris, as had a forward ammunition supply dump. This would require explaining.
Sure enough, he had hardly laid his tired head down on his smelly, lice-ridden pillow when he was awoken and dragged, stumbling, into the sidecar of a military-police motorcycle. As the cool air streamed across his face, he wondered at his fate, knowing the loss of soldiers caught in his blast could easily be sheeted home to a lowly mining lieutenant. Dazed and exhausted, his uniform caked with mud and his face unshaven, he was paraded before Major General H. de B. de Lisle, who angrily questioned him about the blast and informed him he was under arrest. Cassels had lit
tle to say, other than that he thought he was doing his job and had no control of the men who had been positioned so close to the blast.
Suddenly the door behind him opened, and in strode Lieutenant General Sir Edmund Allenby, the commander of the 5th Corps. Cassels was dismissed and sent outside. Soon after, he found himself sitting in Allenby’s staff car, being driven off to lunch somewhere with Allenby and Commander-in-Chief Sir John French, who warmly congratulated him on a great effort. By the end of the day, he had been awarded a Military Cross and granted ten days’ leave in England. Amidst the excitement, his threatened court martial was somehow forgotten.
In all, it had been a great day for the tunnellers. More importantly, Cassels’ bold mining operation was to become the inspiration for John Griffiths’ grand plan for a series of explosions that would rip Messines Ridge apart and provide the breakthrough that the Allies so desperately needed. At the time of the Hooge blast, the Western Front, particularly the staunchly defended Messines Ridge, was still in a gruelling stalemate. Allied attacks at St Eloi had failed, and the ridge protruded dangerously into the Allied front.
Griffiths, in his usual far-sighted and visionary way, thought that what was needed was a well-planned and concentrated attack beginning with a series of massive mine explosions all along the German front. He had been impressed with the effect that Lieutenant Cassels’ mine at Hooge had on the German defenders and believed that if the operation was planned right, the ridge, and certainly the protruding salient, could be virtually flattened out.7 He put the idea to his immediate superior, General Harvey, suggesting that six deep mines be fired by his tunnellers.
General Harvey was impressed and agreed to present the suggestion to the engineer-in-chief, General Fowke. However, the overworked Fowke immediately rejected the plan and cursed Harvey and Griffiths for subjecting him to such a preposterous idea. How could the British tunnellers mount such an attack when the Germans were running rings around them? And anyway, defensive tunnelling was more important. So the idea was shelved.
Griffiths was not one to be put off. With Harvey’s support he eventually brought General Fowke around to the idea late in 1915, but they still needed to convince the British High Command, who were cool on the idea but respected Fowke’s experience. By the end of the year, the idea of a massive mining attack started to gain traction. In early January 1916, Fowke, Harvey and Griffiths were ordered to attend a high-level conference at GHQ and discuss their idea further.
Faced with an audience of grey-headed old men and generals sporting red tabs and braid, Griffiths was in his element and addressed them with his usual enthusiasm and vigour. Here, he said, was the ideal weapon to smash open the German front, break through, and in the process save 10,000 Allied lives. His tunnellers would create what he termed ‘an earthquake’ that would destroy the ridge, swallow the German garrison and shatter the enemy’s nerves.
The generals looked on incredulous. Who was this pompous man, a mere major, with such outrageous ideas? And who was he to speak so forcefully to them? Did he have no respect? Given the litany of frontal attacks that had failed – even those with the support of underground mines – such a ‘breakthrough’ did not seem feasible, and the logistics looked impossible. What was next on the agenda?
Well, the trio had tried, they had put their case. Griffiths had been given the chance to show his best dance steps, but to no avail. High Command rejected the scheme, and so they returned to their billets in a deep state of rejection and despair. Old ways and old thinking were still prevalent, and the concept of a new, aggressive mining operation to break the stalemate was simply before its time.
Late that night, a dispatch rider arrived at General Fowke’s quarters with a message marked ‘Urgent’. Tearing open the manila envelope, Fowke’s eye quickly scanned the lines – it was an amazing turnaround. The High Command had thought about the idea and now saw merit in it. They had changed their minds. Fowke raced across and woke Harvey and Griffiths and blurted out the news: they liked the idea of an earthquake, he said, and the tunnelling attack on the Messines Ridge had been given the green light. The tunnelling companies were back in business in a big way.
Fowke, Harvey and Griffiths’ presentation to High Command had been serendipitously timed. The Allies had already decided they needed to mount a major offensive: something really big that might blow open the front and win the war. Planning was already secretly under way for what would become the Somme offensive of July 1916, and if there could be a parallel offensive in the north, along the agonising Ypres salient, then there was value in the Messines idea. If it did allow a breakthrough, perhaps the British could carry the offensive to the coast, an enticing possibility.
While Griffiths was developing his plans for a bold mining operation along the Ypres salient, more new British tunnelling companies were being formed, and they joined existing ones to begin the takeover of the French line north of the Somme. Here the mining conditions were very different from those of Belgian Flanders. The trenches abandoned by the French were full of their unburied dead, often two and three deep. They were shallow and in some places only 30 metres from the Germans, making them extremely dangerous. Instead of running sand and blue clay for the tunnellers to dig down into, there was chalk. On the plus side, it required far less internal support. But while clay allowed the tunnellers to dig silently, tunnelling in chalk was noisy, and neither side could easily mask their operations. It also increased the risk of gas poisoning as the carbon monoxide produced after mine explosions seeped into the porous chalk and lingered. On average, three men would become gas casualties each day.
Carbon monoxide poisoning is a silent killer. Being colourless, odourless, tasteless and not causing any irritation to airways, eyes or skin, it is difficult to detect. A low dose for six to eight hours leads to vertigo, disorientation, headaches. More serious exposure brings severe headaches in one to two hours, and a high dose means headaches, nausea and dizziness within five to ten minutes, and death within half an hour. Men often staggered from a gas-filled mine shaft and collapsed on the surface. Others, overcome by the gas, could not climb ladders and died at the shaft bottom or fell from the ladders, too weak and disorientated to climb to safety. Even those who did make it to fresh air were often hospitalised for long periods suffering from memory loss, depression, severe head pain and confusion as the toxicity in their system affected their heart and their nervous systems.
Men were also affected in small, airless shelters and dugouts, as wood heaters, petrol-powered equipment and portable stoves all created carbon monoxide gas. This was especially the case in winter when draughts into shelters were blocked or covered by snow. The men had only the crudest ventilation and exhaust equipment in the tunnels; some said it was left over from the Crimean War in the 1850s, so they used caged mice and birds as their early warning system to detect gas.
To protect themselves from carbon monoxide poisoning, rescue teams and tunnellers working in dangerously poor air quality wore Proto kits. A Proto kit was an apparatus that consisted of two cylinders of oxygen and a large re-breather bag with separate inhaling and exhaling compartments, from each of which ran a tube up to the mouth. The cylinders of oxygen were carried on the back and the re-breathing bag lay on the chest, giving rescuers freedom of movement, and as there were no parts of the apparatus that projected out to the side, the kits could not be damaged in the confines of a tunnel. The rest of the kit included a pair of smoke goggles worn over a skull cap, and a nose clip that forced them to breathe only through the mouth, enabling them to work for up to two hours in safety.
The Proto kits were developed from an apparatus used on the English coalfields. In June 1915, six Proto sets were dispatched to the Royal Engineers to assess their suitability. Two experienced mine-rescue workers, Corporal Ellison and Lance Corporal Clifford, trained 12 tunnellers to operate the equipment. The kits were approved for use, and they extended the training to the other tunnelling companies. By the end of 1915, they had traine
d nearly 3000 men. Their work resulted in the formation of the Mine Rescue School at Armentières.
The British tunnellers on the Somme trialled some new tactics. At the Old Mill mine near Cuinchy, they fired two small mines to draw the Germans to the frontline in anticipation of an attack, but these small explosions were no more than bait. As expected, the Germans crowded into their firing line, just in time for the much larger charge to be fired. This smashed a long section of trench, killing many of the enemy garrison and wiping out the defences in this section of the line.
In late July, the 174th Company established a headquarters at Bray-sur-Somme and took over 66 French shafts between La Boisselle and Maricourt, including some at Carnoy and Fricourt. The dashing, handsome grandson of the Duke of Wellington, Captain Edward Wellesley, established his headquarters just north at Méaulte near Albert, and his newly formed 178th Company began works in the French tunnels at Tambour Duclos, near Fricourt. The 179th, also recently formed, began work at La Boisselle, just to the northeast of Albert. This concentration of mining companies began the work that would see the explosion of nine mines on the opening day of the Battle of the Somme, including the massive Lochnagar mine, the crater where many visitors pay their respects today.
Wellesley’s orders were clear: the 178th Company was to destroy the enemy tunnels and workings, undertake offensive mining against the German positions at Fricourt and hold the high ground at Tambour. From the time the British tunnellers took over the maze of French workings, the sound of German mining was clear as they aggressively pushed towards the British line. A deadly game of cat and mouse developed, as each side dug forward, listened, fired a camouflet and drove on. It was when the sound of the enemy’s digging stopped that the period of real danger began, as this was when the explosive charges were laid, the tamping completed and the mine fired. Officers needed to interpret the sounds and withdraw their men quickly, before the enemy fired their mine.
