nder WELLINGTON, depended, upon the contrary, upon the
North Sea, and upon communication across that sea with England. That is,
it drew its supplies and the necessaries of its existence from the _west_,
the opposite and contrary direction from that to which the Prussian half
of the Allies were looking for theirs. The effect of this upon the
campaign is at once simple to perceive and of capital importance in
Napoleon's plan.

Wellington and Blucher did not, under the circumstances, oppose to
Napoleon a single body drawing its life from one stream of communications.
They did not in combination command a force defending one goal; they
commanded two forces defending two goals. The thorough defeat of one
would throw it back away from the other if the attack were delivered at
the point where the two just joined hands; and the English[1] or western
half under Wellington was bound to movements actually contrary to the
Prussian or eastern half under Blucher in case either were defeated before
the other could come to its aid.

Napoleon, then, in his rapid advance upon Belgium, was a man conducting a
column against a line. He was conducting that column against one special
point, the point of junction between two disparate halves of an opposing
line. He advanced therefore upon a narrow front perpendicular to, and
aimed at the centre of, the long scattered cordon of his double enemy,
which cordon it was his business if possible to divide just where the
western end of one half touched the eastern end of the other. He designed
to fight in detail the first portion he could engage, then to turn upon
the other, and thus to defeat both singly and in turn.

I will put this strategical position before the reader in the shape of an
English parallel in order to make it the plainer, and I will then, by the
aid of sketch maps, show how the Allies actually lay upon the Belgian
frontier at the moment when Napoleon delivered his attack upon it.

Imagine near a quarter million of men spread out in a line of separate
cantonments from Windsor at one extremity to Bristol at the other; and
suppose that the eastern half of this line from Windsor to as far west as
Wallingford is depending for its supplies and its communications upon the
river Thames and its road system, and is prepared in case of defeat to
fall back, down the valley of that stream towards London.

On the other hand, imagine that the western half from Swindon to Bristol
is receiving i