fire or assault a detached
force which has advanced with such rapidity as to enable the defenders,
without undue risk, to cut off and annihilate the isolated enemy body.
Whatever the tactical situation, it is by the vigour of the offensive
spirit alone that success may be achieved in the face of a determined
enemy.

MODERN WARFARE.--In modern warfare the defensive position plays a part
of increasing importance, owing {80} to the great power conferred on
the defence by modern armaments. "Machine guns and barbed wire permit
the rapid organisation of defensive points of a value which cannot be
disputed. In particular, they have given to a trench, or to a natural
obstacle, a solidity which permits a front to be extended in a manner
unsuspected before this war; they permit the prompt consolidation of a
large system that is easy to hold" (Marshal Foch). "The modern rifle
and machine gun add tenfold to the relative power of the Defence as
against the Attack. It has thus become a practical operation to place
the heaviest artillery in position close behind the infantry fighting
line, not only owing to the mobility afforded by motor traction but
also because the old dread of losing the guns before they could be got
away no longer exists" (Marshal French). It is thus possible to hold
the forward positions of a highly organised defensive system with a
minimum of exposure to loss, the extra strength of the position
counterbalancing the reduction in numbers, but a preference for
defensive action of this kind may generally be regarded as an admission
that a victorious outcome of the campaign is not anticipated at the
time of its adoption in the theatre in which it is employed. "It is of
paramount importance that in those parts of a theatre of operations
where a commander aims at decision a war of movement must never be
allowed to lapse into position warfare so long as a further advance is
possible. Position warfare can never of itself achieve victory"
("Field Service Regulations," vol. ii. (1920)). However strong
entrenchments may be they will not defeat the adversary's main armies,
nor can they withstand indefinitely the attacks of a determined and
well-armed enemy. It is scarcely even probable that an army behind
entrenchments can by that means alone inflict such losses on its
assailants as will enable the initiative, or liberty of manoeuvre, to
be regained and the assailant's main armies to be defeated. The
operations on