The Probert Encyclopaedia of Warfare

BARRAGE

In warfare, a barrage is a linear concentration of artillery fire used to interpose a screen of bursting shells between attacking and defending troops. When fired by a defending force to prevent an attack reaching its lines, a
barrage may be a simple line of fire in front of a position or shaped so as to surround the position - a 'box' barrage. Fired to assist an attack, a
barrage may be stationary, to prevent reinforcements reaching the threatened area, or moving, to act as a continuous screen ahead of the advancing force. Normally using high explosive shells, in the Great War barrages often included gas and shrapnel projectiles so as to present a more complex threat to the target.
Research Barrage