that, provided unity of direction is kept, an overwhelming artillery
surprise (see _F.A. Training_, 1906, p. 225) is carried out more easily
than from a visible position. The extent of _front_ of a battery in
action is governed by the rule that no two gun detachments should be
exposed to being hit by the bullets of one shell, and also by the
necessity of having as many guns as possible at work. These two
conditions are met by the adoption of a 20-yards interval between the
muzzles of the guns. At the present time the gun and its wagon are
placed as close together as possible, to obtain the full advantage of
the armoured equipment. The _shield_, behind which the detachments
remain at all times covered from rifle (except at very short range) and
shrapnel bullets,[3] enables the artillery commander to handle his
batteries far more boldly than formerly was the case. General Langlois
says "the shield-protected carriage is the corollary to the quick-firing
gun." Armour on the wagon, enabling ammunition supply as well as the
service of the gun, to be carried on under cover, soon followed the