Souham’s attitude of mind up to, say, the Thursday may be fairly described in some such terms as follows:—
“I know that a concentration is going on in the valley of the Scheldt to the south and east of me; it is pretty big, but not yet exactly dangerous, though I shouldn’t wonder if I were attacked in a few days from that quarter. What I am much more certain of is that active and mobile force which I beat off the other day, but which is still intact under the best General opposed to me, Clerfayt. I hear that it is marching south again, and my best troops and my offensive must be directed against that. I am far superior in numbers to Clerfayt, and if I can bring him to an action and break him, I can then turn to the others at my leisure: for the moment I have only one front to think of—that on the north.”
But the negligence which he or his informants were guilty of—a negligence that was to prove so nearly fatal to all those 40,000 French troops—consisted in the failure to discover what was up upon Friday the 16th.
During those twenty-four hours the Arch-Duke Charles had brought up his column to St Amand; the other four columns upon the Scheldt were concentrated, and upon the north of the Lys, Clerfayt had got orders to move upon Wervicq, and was, during the middle hours of Friday, actually upon the march. Yet, during all that day, Friday the 16th, Souham remained ignorant of the extremity of his peril.
The orders which he dictated upon the Friday night, and largely repeated upon the following morning of Saturday the 17th of May, show how little he expected the general action that was upon him. He arranged, indeed, for a cordon of troops to be watching, in insufficient numbers, the side towards the Scheldt, and he sent to Bonnaud and the camp at Sainghin, outside Lille, orders to keep more or less in touch with that cordon. The instructions to this cordon of troops along the eastern side of the French position is no more than one of general vigilance. It is still to Clerfayt and towards the north alone that he directs an offensive and vigorous movement.
In a word, he was a good twenty-four hours behind with his information. He was wasting troops north of the Lys in looking for Clerfayt at a time when that General was already on the march to Wervicq, and he was leaving a scattered line of insufficient bodies to meet what he did not in the least expect, the rapid advance of Bussche, Otto, and York during that Saturday upon Mouscron, Tourcoing, and Roubaix.
Therefore it was that although Bussche’s insufficient force was driven out of Mouscron at last by superior numbers, Otto and York succeeded 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.