eeded in
sweeping all the resistance before them, and, in the course of that
Saturday, reached the first Tourcoing, the second Roubaix, and even
Mouveaux.

The whole problem of warfare consists in a comparison between the
information that each side has of the movements of the other. The whole
art of success in war pivots upon the using of your enemy's ignorance. Had
the allies upon this occasion been more accurate in keeping to their
time-table, and somewhat more rapid in their movements, they would have
caught the French commander still under the illusion that there was no
danger, save from the north, and would have succeeded in cutting off and
destroying the main French force by getting in all together between
Courtrai and Lille. For at that same moment, the early hours before
daybreak of the 17th, the allies had begun their movement.

PART V

THE TERRAIN

The terrain over which the plan of the allies was to be tested must next
be grasped if we are to understand the causes which led to its ultimate
failure.

That terrain is most conveniently described as an oblong standing up
lengthways north and south, and corresponding to the sketch map overleaf.
That oblong has a base of twenty miles from east to west, a length from
north to south of thirty-five.

These dimensions are sufficient to show upon what a scale the great plan
of the allies for cutting off Souham at Courtrai was designed.

At its south-eastern corner the reader will perceive the town of St Amand,
the furthest point south from which the combined movements of the allies
began; while somewhat to the left of its top or northern edge, at the
point marked "A," the northern-most body connected with that plan, the
body commanded by Clerfayt, was posted at the origin of the movement.

[Illustration]

The object of the whole convergence from the Scheldt on one hand, and from
Clerfayt's northern position upon the other, being to cut off the French
forces which lay at and south of Courtrai from Lille, and the main line of
the French army, it is evident that the actual fighting and the chances of
success or disaster would take place within a smaller interior oblong,
which I have also marked upon the sketch map. This smaller or interior
oblong measures about sixteen miles at its base by about twenty-five miles
in length, and includes all the significant points of the action.

The points marked 1, 2, 3, 4, and 5 respectively are the points at whic