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
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
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.
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
I'm John Lienhard at the University of Houston, where we’re interested in the way inventive minds
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. And
this article tells about the explosion that killed a cow.
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.