8o
THE YPRES TIMES
Little was known, to begin with, of the soil and unlooked for difficulties arose from
sudden influxes of water. The geophone had not been invented, so that listeners had
to depend on the natural acuteness of their hearing, unaided by any artificial means of
amplification. Under such conditions subterranean operations were often carried on
with only a few feet of earth separating our men from the enemy, both parties being
mutually unaware of each other's presence until some accidental noise, or actual contact
with an opponent's working, betrayed the situation to one of them. Blows were
frequent, and were generally attended with much loss of life. So crowded, indeed, are
old maps of this area with conventional signs indicating craters and camouflets (sub
surface explosions), each accompanied by a legend indicating the fatalities it caused,
that historians of the Salient may well be embarrassed by the wealth of narrative they
suggest.
THE BRIDGE HILL 60 IN 1916—FROM GERMAN FRONT LINE.
Photograph taken by a German prisoner, showing overhead bridge, and beyond it one of our
barricades, and The Mound at Verbrandenmolen. Hill 60 is to the right of view.
Not less dramatic were incidents that occurred later. During 1916, in fact, the
development of underground warfare approached its culmination. While single aerial
combats were being watched daily by countless pairs of eyes, and newspapers, the
world over, reported almost imperceptible changes in line at Verdun or on the Somme,
practically nothing was made known of the grim and silent struggle taking place else
where far below the shell-torn surface of No Man's Land. Only when some violent
concussion shook the earth and it vomited forth an awe-inspiring fountain of smoke and
debris was there comprehensible evidence of this unseen activity. Impenetrable
secrecy regarding everything relating thereto was maintained, partly to prevent informa
tion leaking through to the enemy and partly to not unnecessarily alarm trench garrisons,
though tunnelling officers might, at their discretion, warn infantry of an impending
blow.
Mining tactics are largely dictated by existing geological conditions. In the hard
chalk of Picardy and Artois, for instance, it was comparatively easy for either side to
accurately locate by sound the other's workings, and successful attack or defence became
a matter of concealing one's own and out-guessing an opponent's intention as to when
