"Near Messines, south of Ypres, British miners had been tunneling for a year under the German front lines, and by early June (1917) they had dug twenty-one horizontal mineshafts stuffed with a million pounds of high explosive a hundred feet below crucial points in the German defense system. At 3:10 in the morning (7 JUN) these mines were set off all at once. Nineteen of them went up, and the shock wave jolted Lloyd George in Downing Street 130 miles away. Two failed to explode. One of these went off in July, 1955, injuring no one...The other, somewhere deep underground near Ploegsteert Wood, has not gone off yet."Fussel isn't quite correct, by the way. As the Wiki entry notes, a total of 26 mines were originally dug.
One ("Peckham 2") of a pair was abandoned after the gallery was breached and saturated ("flowing") sand filled the tunnel. Another at La Petite Douve Farm was compromised by German countermining and abandoned to prevent alerting the German counterminers.
Four more, placed under a German strongpoint called "The Birdcage" located at Le Pelerin, near the southern end of Messines Ridge, were never fired because the German defenders abandoned The Birdcage prior to 7 JUN 1917.
That left twenty, and all were detonated that morning.
But the mines of Messines were no more decisive than any other of the technical innovations of WW1. The ensuing attack gained about two miles (three if you start from the furthest end of the original German salient) before the German IV.Armee consolidated and ground the Allied advance to a halt. The killing went on another 16 months until the Armistice of November 1918.
The mines of Messines weren't done in 1918, though.
Not surprisingly, nobody wanted to go back in and laboriously drag all those explosives out of Birdcage 1 through 4, Peckham 2, and La Petite Douve. The groundwater is dangerously high, the running sand dangerous to dig, and the mines themselves were both touchy (guncotton, or nitrocellulose, is notoriously sensitive) and designed to resist water damage. I can't find the plans, but Simon Jones, one of the commentors on the Messines thread at the Great War Forum, said back in 2006 that
"These charges were very carefully waterproofed - the detonators and primers were sealed in bottles, the detonator leads placed in armoured hose and the explosives put into petrol cans covered with canvas coated in tar."That these explosives were still patent nearly forty years later was proved by the detonation of one of the three Birdcage mines:
"One of the...mines went off unexpectedly on 17 June 1955 during a thunderstorm, near Le Pelerin. Electrification of the area had arrived in the 1940s and 50s, and a pylon was unknowingly erected above the site of the mine; lightning struck the pylon, detonating the mine below. The only casualty was a dead cow, although surrounding damage was extensive. The resultant crater has since been filled in, although after heavy rainfall a slight depression in the ground indicates the location of the crater."That leaves five; Peckham 2 (a relatively small mine of about 20,000 pounds of explosive), the other three Birdcage mines, and the Petite Douve mine.
Which is, at the moment, about 25 tons of high explosive buried about 70 feet (23 meters) below one of the barns of the farm in the picture below.
M. Roger Mathieu, current owner and resident of the farm now known as La Basse Cour, isn't worried. "It doesn't stop me sleeping at night. It's been there all that time, why should it decide to blow up now?"
(If you're interested, the Clevelode battlefield tours website has a very good little photo tour of the Messines sites today.)
As William Faulkner said; sometimes the past isn't just "not dead".
Sometimes it's not even past.