_Before the battle._--Metaphorically speaking, the Flying Corps
(aeroplanes and observation balloons) is the "eye" of the High Command,
which largely depends on it for precise information regarding the
enemy's movements and positions. It likewise regulates the artillery
fire, and furnishes that arm with photographs, showing exactly the
progress made by the destruction bombardments. Another equally
important duty is to "blind the enemy" by destroying their aeroplanes
and observation balloons.
[Illustration: OBSERVATION BALLOON.]
_During the battle._--Flying low, sometimes within a few hundred feet
of the ground, the airmen furnish invaluable information, and often
photographs, showing the progress of the attack, the _terrain_ being
marked out with panels and Bengal lights. They also often attack the
enemy with their machine-guns.
[Illustration: BRITISH TANKS MAKE THEIR DÉBUT.]
_After the battle._--The massing of enemy troops for counter-attacks is
signalled to the artillery, which regulates its barrages accordingly,
then, working in _liaison_, the two services "prepare" the ground for
the next attack.
These tactics were, gradually perfected on the Somme battlefields,
where the Germans learned by costly experience to improve their
defences.
[Illustration: GENERAL FAYOLLE INSPECTING THE CONQUERED LINES.]
The offensive methods acquired also greater suppleness, and the new
arm--=the tank=--came to the relief of the infantry.
[Illustration: THE DOTTED ZONES REPRESENT THE GERMAN LINES OF
RESISTANCE.]