to the
direction of the retreat, to make detachments which can be overthrown
by sudden counter-attacks, or to lure a pursuer from the field where
their presence is required, as Grouchy was lured after Napoleon's
defeat of the Prussians at Ligny {91} (June 16, 1815). The object of
Napoleon's attack on the Allies was the separation of Wellington's
Anglo-Belgian force from the Prussian Army under Bluecher, and after the
defeat of the latter at Ligny the Emperor directed Marshal Grouchy to
pursue the Prussians and to drive them eastwards. Grouchy conducted a
leisurely pursuit and engaged an insignificant part of the Prussian
Army (_The Battle of Wavre_, June 18-19, 1815), while the main body of
the Prussians moved westwards and assisted in the overthrow of Napoleon
at Waterloo.

(x) _There should be favourable ground and a good line of advance for
the Decisive Counter-Attack_. In order, therefore, to overthrow the
enemy, a position should not be chosen behind an impassable feature
which neither side can cross. At _Ramillies_ (May 23, 1706), one wing
of the enemy was posted behind a marsh, where it was both unassailable
and unable to attack. Marlborough, therefore, ignored that wing
entirely, and bringing his whole force against the remaining wing, won
easily a decisive victory. The only occasions when an impassable
feature is welcome are in the Passive Defence of a small force against
overwhelming odds (as was seen in August, 1914, when the Belgians
occupied a position behind the _River Gette_), and in the Delaying
Action of a Rear-guard fighting for time for the Main Body to get away.
In such cases a Decisive Counter-Attack is not contemplated.

OCCUPATION OF A DEFENSIVE POSITION.--The framework of the _defence_ is
provided by artillery and machine-gun fire; the backbone of the
_offence_ is the infantry. The Commander will _divide the troops_ into
(a) _Troops to hold the position_, and (b) _General Reserve_, the
golden rule being to make (a) as small as the tactical situation
permits in order that (b) may be as large as possible, and its work
absolutely decisive. Under no circumstances {92} should the General
Reserve be much below half the available force.

Of these two portions, the _Troops to hold the position_ consist of
infantry occupying a series of mutually supporting tactical strong
points, not necessarily continuous, and of irregular alignment so as to
cover with the defender's fire not only the ground o