side found an opportunity to inflict some local damage on the other.
For the Allies it was part of the "war of attrition," or General
Joffre's "nibbling process."

The Germans had gone through a bitter experience in Champagne; with
characteristic skill and energy they set to work improving their
defenses. At intervals of approximately 500 yards behind their second
line they constructed underground strongholds known as "starfish
defenses," which cannot be detected from the surface: About thirty
feet below the ground is a dugout of generous dimensions, in which are
stored machine guns, rifles, and other weapons. Leading from this
underground chamber to the surface are five or six tunnels, jutting
out in different directions, so that their outlets form half a dozen
points in a circle with a diameter of perhaps 100 yards. In each of
the tunnels was laid a narrow-gauge railway to allow the machine guns
to be speedily brought to the surface. At the mouth of the tunnels
were two gun platforms on either side, and the mouth itself was
concealed by being covered over with earth or grass. The defenses were
also mined, and the mines could be exploded from any one of the
various outlets. On several occasions when the French endeavored to
press home their advantage they found themselves enfiladed by machine
guns raised to the surface by troops who had taken up their places in
the underground strongholds at the first menace to the second line.
When one of the outlets was captured, machine guns would appear at
another; while, if the French troops attempted to rush the stronghold,
the Germans took refuge in the other passages, and met them as they
appeared.

On the French and British side also, underground defense works were of
a most scientific and elaborate character. Trench warfare has become
an art. Away from the seat of war the importance of the loss or the
gain of a trench is measured by yards. If you are in trenches on the
plain, where the water is a few feet below the surface, and all the
area has been used as a cockpit, you would wonder how any trench can
be held. If, on the other hand, you were snugly installed in a deep
trench on a chalk slope, you would wonder how any trench can be lost.
Any real picture of what a trench is like cannot be drawn or imagined
by a sensitive people. It is, of course, a graveyard--of Germans and
British and French. Miners and other workers in the soil drive their
tunnel or trench into inconce