"Unless such exercises are carried out in a
practical manner, young officers and inexperienced N.C.O.'s will get
the impression that an Advanced Guard consists merely of a procession
of small bodies of infantry, strung out at fixed intervals on a single
road. It is of the highest importance that the training should be
carried out on the lines that would be adopted in action" (G.H.Q.
Circular).

TACTICAL PRINCIPLES.--"Speed of advance is the first consideration when
not in contact with the enemy. Hence an Advanced Guard will move on a
narrow front along roads and other channels of communication, with such
distances between advanced and supporting bodies as to avoid
possibility of surprise. When in contact with, or in the vicinity of,
the enemy, security and speed of advance are equal considerations.
Hence the Advanced Guard should move by bounds on a broad fighting
front across country" ("Infantry Training, 1921").

Before an Advanced Guard commander moves off in compliance with his
instructions he will take certain steps in accordance with these
tactical principles. He will divide his troops into two portions,
known as the _Vanguard_ and the _Main Guard_, and as the duties of the
{106} Vanguard are reconnaissance in general, as well as the protection
in particular of the Main Guard, it will contain a large proportion of
mobile troops, with infantry for assault and resistance, and engineers
for clearing the way through or over obstacles. Aircraft, in advance
of the Vanguard, not only increase the area under search and expedite
the discovery of the enemy, but prevent surprise and assist the
Advanced Guard as a whole by close co-operation in feeling for and
fighting the enemy when encountered. "In order to reconnoitre one must
compel the enemy to show himself wherever he may be. To this end he
has to be attacked until the extent of his position has been clearly
defined. But the attack is made with the intention not to bring on an
action. The skirmishing lines will advance, but they must be able to
disengage themselves at a given moment. Pressure is exercised from a
distance without allowing the forces exerting that pressure to become
tied up" (Marshal Foch). The duty of the Main Guard is Resistance,
that is to say, fighting. It will therefore consist mainly of
infantry, with artillery and machine guns, and the troops will move in
the order in which they will come into action. The Vanguard will be
preceded b