time to his base, with his
budget of news, and may bring with him a series of photographs.

POSITION WARFARE.--When opposing forces are entrenched at no great
distance from one another, photographs taken from the air lead to the
discovery of new works from which the intentions of the enemy can be
predicted. On the Western Front in the Great War, photographs taken
from the air revealed the construction in the German training area of
actual sectors of British trenches in facsimile, thus indicating the
rehearsal of an attack on a definite part of the line. Hostile
aircraft are prevented from carrying out similar observational
journeys, the resistance of defending squadrons is overcome, and
whenever a favourable target is presented, casualties are caused by
bullets and bombs. Observers report all suspicious movements and
changes in trench construction, and from photographs taken at daily
intervals maps of hostile trenches are constructed and revised.
Infantry patrols and raiding parties are sent out by night and by day,
and information is gleaned from the uniforms and badges of captured
prisoners as to the distribution of hostile troops, while changes in
the plan of trenches, in the siting of wire entanglements, or in the
emplacements of guns and mortars are duly noted. In addition, troops
in observation posts, in or ahead of the front line, in favourable and
unsuspected {100} localities, are constantly observing the enemy, and
sentries over all posts containing troops are ready at all times of the
day and night to alarm the local garrisons. Resistance is afforded by
a series of mutually supporting strong points, sufficiently garrisoned
by troops who guard against surprise and hold their ground against
attack. Entrenchments, with dug-outs and shelters, provide protection
from fire, and barbed wire entanglements prevent unbroken rushes by the
enemy, and entice him into openings that are swept by rifle and
machine-gun fire. Box respirators and other appliances nullify the
effects of gas, and camouflage disguises the position of trenches,
troops, guns, and dumps, and so screens them from observation and
direct bombardment, while it provides unsuspected means of observing
the enemy's movements.

MANOEUVRE WARFARE.--In a War of Manoeuvre the steps taken to obtain
security against surprise vary with the situation of the troops.
Hostile aircraft flying high from the ground are dealt with by
counter-attack by armed aeropl