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No. 3138:
Messines Explosion

Today, a very big explosion. The University of Houston presents this series about the machines that make our civilization run and the people whose ingenuity created them. 

I once did a program on the Petersburg Battle of the Crater. How the Union Army drilled a long tunnel and planted four tons of explosives under Confederate lines. How it went off and killed almost three hundred soldiers. But then: The Union soldiers charged through the crater and found themselves trapped in it. The South rallied and killed almost four thousand of them.

Tunneling in war gets tricky. So let's visit the most horrific tunneling attack of all - the WW-I Battle of Messines. 1915 found German troops entrenched on Messines Ridge, along the northern French/Belgian border. How to dislodge them?

The British began drilling tunnels under no-man's land, so they could set explosives under the German line. It was a huge operation. Over two years' time they bored 26 tunnels. Then they loaded between 7 and 43 tonnes of amatol into each one. Amatol is a mixture of TNT and ammonium nitrate.

The Germans knew something was afoot. But the British dug diversionary tunnels near the surface. The Germans found and blocked those tunnels. They thought they had the problem in hand. But the real British tunnels were much deeper, and they went undetected. 

The British set off 20 mines before dawn, July 7, 1917. It was then the largest man-made explosion ever - about a half a kilotonne. Londoners felt the blast 140 miles away - across the English Channel. 

The result was devastating. Some ten thousand German soldiers died in an augenblick - in the blink of an eye. The British did manage to drive the Germans back and gain some ground in the Ypres Salient. But, in the end, the British and Germans each lost around 25,000 men, and the war still had far to go. 

Notice that only 20 of the tunnels yielded explosions. Positions had shifted over the two year period, so five tunnels were no longer in the right place, and another had collapsed. The mine in one of those finally went off in 1955 when lightning hit an electrical pole above it. Its only casualty was a grazing cow. Another 23-tonne mine lies 80 feet under a Belgian farm. No one there seems worried. Maybe the Belgians are casual because they've been digging up unexploded ordnance from two wars, for over a century. 

Pool of Peace
The Spanbroekmolen Pool of Peace

Visit the site today and you'll find a memorial called the Pool of Peace. It's a small lake that fills the Spanbroekmolen Crater. That's where the largest blast went off - 43 tonnes. It's named after a windmill that stood there before war began. 

Nearby, a mere 58 of the soldiers who died in the Battle of Messines Ridge rest in a small British cemetery. That seems like nothing beside the millions who died in all the explosions, big or small, of that war. Those legions rest somewhere beyond human comprehension. But we are able to get our minds around 58 once-living people - people with stories and with names. 

Spanbroekmolen British Cemetery
Spanbroekmolen British Cemetery

I'm John Lienhard at the University of Houston, where we're interested in the way inventive minds work.

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See the Wikipedia pages on Mines in the Battle of Messines (1917) The Largest artificial non-nuclear explosions, And The Spanbroeken Pool of Peaceand British Cemetery. Images above are courtesy of Wikimedia Commons.

This article from The Telegraph tells about the farm above one of the unexploded mines. 

This Austrailian War Memorial page includes photos of the aftermath of the explosion.

This Mining Magazine presents a great deal of additional detail and photographs

Aerial view of the Spanbroekmoler Crater today
Google Earth view of Spanbroekmolen Crater as of August 6, 2017

This episode was first aired on August 11, 2017