On the 7th of June, 1917, during the First World War, the village of Messines, Belgium was

rocked to its core by a massive earthquake.

Or at least, that's what the German soldiers occupying the area thought it was.

It was only when they saw the bodies of their comrades flung into the sky which was burning

orange with flames that they suddenly

realized this was no earthquake. This was a blast. Once so huge it annihilated some 10,000

German soldiers, injured thousands more, and produced shockwaves felt as far away as France.

But the most incredible part was that the explosion hadn't

come from a bomb or artillery that rained down from above. It had originated from right under their feet.

How on earth had something capable of an explosion of this magnitude gone completely undetected by so

many men? The answer lay deep underground. This was where a

specialist unit of Canadian, Australian, New Zealand, and British tonnilers had worked tirelessly

to set up one of the largest man-made explosions in all of human history. While the horrors of the

trenches have been well documented, the story of these tunnelers isn't as widely known, though it's arguably even more harrowing.

So get ready, because I promise what you're going to learn about these amazing men will blow you away.

You're listening. You're listening to be amazed.

To uncover the full story, first we need to rewind to the start of World War I.

In August 1914, German forces ripped through French and Belgian defenses.

Their advance wouldn't last, though.

One month later at the Battle of Ayn in eastern France,

French and British forces stubbornly halted the German offensive.

With both sides struggling to overpower one another, a stalemate ensued.

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