“This way,” said the officer who had added four soldiers to the party to carry the various bags and packages which Desnoyers had brought out on the roof of the automobile.

They proceeded in a single file the length of a wall of blackened bricks, down a steep hill.  After a few steps the surface of the ground was about to their knees; further on, up to their waists, and thus they disappeared within the earth, seeing above their heads, only a narrow strip of sky.  They were now under the open field, having left behind them the mass of ruins that hid the entrance of the road.  They were advancing in an absurd way, as though they scorned direct lines—­in zig-zags, in curves, in angles.  Other pathways, no less complicated, branched off from this ditch which was the central avenue of an immense subterranean cavity.  They walked . . . and walked . . . and walked.  A quarter of an hour went by, a half, an entire hour.  Lacour and his friend thought longingly of the roadways flanked with trees, of their tramp in the open air where they could see the sky and meadows.  They were not going twenty steps in the same direction.  The official marching ahead was every moment vanishing around a new bend.  Those who were coming behind were panting and talking unseen, having to quicken their steps in order not to lose sight of the party.  Every now and then they had to halt in order to unite and count the little band, to make sure that no one had been lost in a transverse gallery.  The ground was exceedingly slippery, in some places almost liquid mud, white and caustic like the drip from the scaffolding of a house in the course of construction.

The thump of their footsteps, and the friction of their shoulders, brought down chunks of earth and smooth stones from the sides.  Little by little they climbed through the main artery of this underground body and the veins connected with it.  Again they were near the surface where it required but little effort to see the blue above the earth-works.  But here the fields were uncultivated, surrounded with wire fences, yet with the same appearance of Sabbath calm.  Knowing by sad experience, what curiosity oftentimes cost, the official would not permit them to linger here.  “Keep right ahead!  Forward march!”

For an hour and a half the party kept doggedly on until the senior members became greatly bewildered and fatigued by their serpentine meanderings.  They could no longer tell whether they were advancing or receding, the sudden steeps and the continual turning bringing on an attack of vertigo.

“Have we much further to go?” asked the senator.

“There!” responded the guide pointing to some heaps of earth above them.  “There” was a bell tower surrounded by a few charred houses that could be seen a long ways off—­the remains of a hamlet which had been taken and retaken by both sides.

By going in a direct line on the surface they would have compassed this distance in half an hour.  To the angles of the underground road, arranged to impede the advance of an enemy, there had been added the obstacles of campaign fortification, tunnels cut with wire lattice work, large hanging cages of wire which, on falling, could block the passage and enable the defenders to open fire across their gratings.