e earthquake of the explosions.

For two years there had been fierce underground fighting at Hill 60
and elsewhere, when our tunnelers saw the Germans had listened to one
another's workings, racing to strike through first to their enemies'
galleries and touch off their high-explosive charges. Our miners, aided
by the magnificent work of Australian and Canadian tunnelers, had beaten
the enemy into sheer terror of their method of fighting and they had
abandoned it, believing that we had also. But we did not, as they found
to their cost.

I had seen the working of the tunnelers up by Hill 70 and elsewhere. I
had gone into the darkness of the tunnels, crouching low, striking
my steel hat with sharp, spine-jarring knocks against the low beams
overhead, coming into galleries where one could stand upright and walk
at ease in electric light, hearing the vibrant hum of great engines, the
murmur of men's voices in dark crypts, seeing numbers of men sleeping
on bunks in the gloom of caverns close beneath the German lines, and
listening through a queer little instrument called a microphone, by
which I heard the scuffle of German feet in German galleries a thousand
yards away, the dropping of a pick or shovel, the knocking out of German
pipes against charcoal stoves. It was by that listening instrument,
more perfect than the enemy's, that we had beaten him, and by the grim
determination of those underground men of ours, whose skin was the color
of the chalk in which they worked, who coughed in the dampness of the
caves, and who packed high explosives at the shaft-heads--hundreds of
tons of it--for the moment when a button should be touched far away, and
an electric current would pass down a wire, and the enemy and his works
would be blown into dust.

That moment came at Hill 60 and sixteen other places below the
Wytschaete and Messines Ridge at three-thirty on the morning of June
7th, after a quiet night of war, when a few of our batteries had
fired in a desultory way and the enemy had sent over some flocks of
gas-shells, and before the dawn I heard the cocks crow on Kemmel Hill.
I saw the seventeen mines go up, and earth and flame gush out of them as
though the fires of hell had risen. A terrible sight, as the work of men
against their fellow--creatures... It was the signal for seven hundred
and fifty of our heavy guns and two thousand of our field--guns to open
fire, and behind a moving wall of bursting shells English, Irish, an