_Before the battle_, the artillery must destroy the enemy's wire
entanglements, trenches, shelters, blockhouses, observation-posts,
etc.; locate and engage his guns; hamper and disperse his working
parties.
_During the battle_, it must crush enemy resistance, provide the
attacking infantry with a protecting screen of fire, by means of
creeping barrages, and cut off the defenders from supplies and
reinforcements by isolating barrages.
_After the battle_, it must protect the attacking troops who have
reached their objectives, from enemy counter-attacks, by barrage fire.
[Illustration: CAMOUFLAGED HEAVY GUN ABOUT TO FIRE.]
[Illustration: THE CAPTURE OF VERMANDOVILLERS.
_The arrival of French reinforcements. Photographed from accompanying
aeroplane at 600 feet (p. 128)._]