On the 13th, Tuesday, the orders of the Emperor to both Clerfayt and the Duke of York (which are also on record) set down this plan in detail, mentioning the point Wervicq at which Clerfayt was expected to cross the river Lys, and at the same time directing the Duke of York to march northward with the object of joining Clerfayt, and thus cutting off the French forces massed round Courtrai from their base. Further, in this same despatch, the initiative is particularly left to the Duke of York, and it is once more from him that Clerfayt is to await decisions as to the moment and details of the operation. The same archives record the Duke of York sending Lieut.-Colonel Calvert to Clerfayt upon the 14th, to tell him that he meant to attack upon the morrow, the 15th, and they further inform us that it was on the English Prince's learning how scattered were Clerfayt's units, and how long it would therefore take him to concentrate, that action was delayed by some thirty-six hours. Evidence of this sort is absolutely conclusive. The plan was not Mack's; it was York's. PART IV THE PRELIMINARIES OF THE BATTLE Tourcoing is an action the preliminaries of which are easy to describe, and need occupy little of our space, because it was a battle in which the plan of one side was developed and prosecuted almost to its conclusion without a corresponding plan upon the other side. As a rule, the preliminaries of a battle consist in the dispositions taken by each side for hours or for days--sometimes for weeks--beforehand, in order to be in a posture to receive or to attack the other side. These preliminaries include manoeuvring for position, and sometimes in the fighting of minor subsidiary actions before the main action takes place. Now, in the case of Tourcoing, there was none of this, for the French at Tourcoing were surprised. The surprise was not complete, but it was sufficiently thorough to make the whole of the fighting during the first day, Saturday (at least, the whole of the fighting in the centre of the field), a triumph for the allied advance. Let us first appreciate exactly how matters looked to Souham when, on the 15th, the Thursday, the blow was about to fall upon him. He had under his orders, with headquarters now at Courtrai, now at Menin (see sketch map on p. 58), rather less than 40,000. In that dash upon Courtrai a fortnight before, which had led to the dangerous establishment of so large an advanced body in front of the main French line, one main effect of that advance had been to push back, away to the left beyond the Lys, more than 16,000, but less than 20,000 men under the Austrian General, Clerfayt. With that army, Clerfayt's body, Souham had remained continually in touch. Detachments of it were continually returning to the valley of the Lys to harass his posts, and, in a word, Clerfayt's was the only force of the enemy which Souham thought he had need to bear in mind.